Technology of Food Products –II

(Fruits & vegetables, Chocolate & Confectionery, Tea, Coffee and Spices)

Part-A (Fruits & vegetables)

The quality of processed fruit products depends on their quality at the start of processing; therefore, it is essential to understand how maturity at harvest, harvesting methods, and postharvest handling procedures influence quality and its maintenance in fresh fruits between harvest and process initiation. Using such information, an appropriate system for harvesting and handling each kind of fruit can be selected and used in conjunction with an effective quality control program to ensure the best quality possible for fresh fruits when processed. Quality attributes of fresh fruits include appearance, texture, flavor, and nutritive value. Appearance factors include size, shape, color, and freedom from defects and decay. Texture factors include firmness, crispness, and juiciness. Flavor components incorporate sweetness, sourness (acidity), astringency, bitterness, aroma, and off-flavors. Nutritional quality is determined by a fruit’s content of vitamins (A and C are the most important in fruits), minerals, dietary fiber, carbohydrates, proteins, and antioxidant phytochemicals (carotenoids, flavonoids, and other phenolic compounds). Safety factors that may influence the quality of fresh fruits include residues of pesticides, presence of heavy metals, mycotoxins produced by certain species of fungi, and microbial contamination. Losses in fresh fruits between harvest and processing may be quantitative (e.g., water loss, physical injuries, physiological breakdown, and decay) or qualitative (e.g., loss of acidity, flavor, color, and nutritive value). Many factors influence fruit quality and the extent of postharvest losses that can occur in the orchard, during transportation, and throughout the handling system (sorting, sizing, ripening, cooling, and storage). The total time between harvesting and processing may also be an important factor in maintaining the quality and freshness of fruit. Minimizing the delays throughout the postharvest handling system greatly reduces quality loss, especially in highly perishable fruits such as strawberries, raspberries, blackberries, apricots, and cherries.

CLASSIFICATION OF FRUITS

Fruit are commonly classified by growing region as follows: temperate-zone, subtropical, and tropical. Growing region and environmental conditions specific to each region significantly affect fruit quality. Examples of fruit grown in each region are listed below

1. TEMPERATE-ZONE FRUITS

1. Pome fruits: apple, Asian pear (nashi), European pear, quince

2. Stone fruits: apricot, cherry, nectarine, peach, plum

3. Small fruits and berries: grape (European and American types), strawberry, raspberry, blueberry, blackberry, cranberry

2. SUBTROPICAL FRUITS

1. Citrus fruits: grapefruit, lemon, lime, orange, pummelo, tangerine, and mandarin

2. Noncitrus fruits: avocado, cherimoya, fig, kiwifruit, olive, pomegranate

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3. TROPICAL FRUITS

1. Major tropical fruits: banana, mango, papaya, pineapple

2. Minor tropical fruits: carambola, cashew apple, durian, guava, longan, lychee, mangosteen,

passion fruit, rambutan, sapota, tamarind

CONTRIBUTION OF FRUITS TO HUMAN NUTRITION

Fruits are not only colorful and flavorful components of our diet, but they also serve as a source of energy, vitamins, minerals, and dietary fiber. The U.S. Department of Agriculture Dietary Guidelines encourage consumers to enjoy “five a day,” i.e., eat at least two servings of fruit and three servings of vegetables each day and to choose fresh, frozen, dried, or canned forms of a variety of colors and kinds of fruits and vegetables. In some countries, consumers are encouraged to eat up to 10 servings of fruits and vegetables per day. For more information access one or more of the following Websites: www.nutrition.gov, www.5aday.gov, and www.5aday.org.

1. ENERGY(CALORIES)

1. Carbohydrates: banana, breadfruit, jackfruit, plantain, dates, prunes, raisin

2. Proteins and amino acids: nuts, dried apricot, fig

3. Fats: avocado, olive, nuts

2. VITAMINS

1. Fresh fruits and vegetables contribute about 91% of vitamin C, 48% of vitamin A, 27% of vitamin B6, 17% of thiamin, and 15% of niacin to the U.S. diet.

2. The following fruits are important contributors (based on their vitamin content and the amount consumed) to the supply of indicated vitamins in the U.S. diet: Vitamin A: apricot, peach, cherry, orange, mango, papaya, persimmon, pineapple, cantaloupe, watermelon Vitamin C: strawberry, orange, grapefruit, kiwifruit, pineapple, banana, apple, cantaloupe Niacin: peach, banana, orange, apricot Riboflavin: banana, peach, orange, apple, avocado Thiamin: orange, banana, grapefruit, apple

3. MINERALS

1. Fresh fruits and vegetables contribute about 26% of the magnesium and 19% of the iron to the U.S. diet.

2. The following fruits are important contributors to the supply of indicated minerals in the U.S. diet:

Potassium: banana, peach, orange, apple, dried fruits such as apricot and prune Phosphorus: banana, orange, peach, fig, raisin Calcium: tangerine, grapefruit, orange Iron: strawberry, banana, apple, orange

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4. DIETARY FIBER

1. All fruits and nuts contribute to dietary fiber. Dietary fiber consists of cellulose, hemicellulose, lignin, and pectic substances, which are derived primarily from fruit cell walls and skin.

2. The dietary fiber content of fruits ranges from 0.5 to 1.5% (fresh weight basis).

3. Dietary fiber plays an important role in relieving constipation by increasing water-holding capacity of feces. Its consumption is also linked to decreased incidence of cardiovascular disease, diverticulosis, and colon cancer.

5. ANTIOXIDANTS

1. Fruits, nuts, and vegetables in the daily diet have been strongly associated with reduced risk for some forms of cancer, heart disease, stroke, and other chronic diseases. This is attributed, in part, to their content of antioxidant phytochemicals.

2. Red, blue, and purple fruits (such as apple, blackberry, blueberry, blood orange, cranberry, grape, nectarine, peach, plum, prune, pomegranate, raspberry, and strawberry) are good sources of flavonoids and other phenolic compounds that are positively correlated with antioxidant capacity of the fruit.

3. Orange-flesh fruits (such as apricot, cantaloupe, mango, nectarine, orange, papaya, peach, persimmon, and pineapple) and some red-flesh fruits (such as tomato, watermelon, and pink grapefruit) are good sources of carotenoids. Availability of lycopene to humans is increased during tomato processing.

FACTORS INFLUENCING COMPOSITION AND QUALITY OF FRUITS

1. PREHARVESTF ACTORS

1. Genetic: selection of cultivars, rootstocks. Cultivar and rootstock selection are important because there are often differences in raw fruit composition, postharvest-life potential, and response to processing. In many cases, fruit cultivars grown for fresh market sale are not optimal cultivars for processing.

2. Climatic: temperature, light, wind. Climatic factors may have a strong influence on nutritional quality of fruits. Light intensity significantly affects vitamin concentration, and temperature influences transpiration rate, which will affect mineral uptake and metabolism.

3. Cultural practices: soil type, soil nutrient and water supply, pruning, thinning, pest control. Fertilizer addition may significantly affect the mineral content of fruit, while other cultural practices such as pruning and thinning may influence nutritional composition by changing fruit crop load and size.

2. MATURITY AT HARVEST AND HARVESTING METHOD

Maturity at harvest is one of the primary factors affecting fruit composition, quality, and storage life. Although most fruits reach peak eating quality when harvested fully ripe, they are usually

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picked mature, but not ripe to decrease mechanical damage during postharvest handling. Harvesting may also mechanically damage fruit; therefore, choice of harvest method should allow for maintenance of quality.

3. POST HARVEST FACTORS

1. Environmental: temperature, relative humidity, atmospheric composition. Temperature management is the most important tool for extension of shelf life and maintenance of the quality of fresh fruit. Relative humidity influences water loss, decay development, incidence of some physiological disorders, and uniformity of fruit ripening. Optimal relative humidity for storage of fruits is 85 to 90%. Finally, atmospheric composition (O2, CO2, and C2H4, in particular) can greatly affect respiration rate and storage life.

2. Handling methods: Postharvest handling systems involve the channels through which harvested fruit reaches the processing facility or consumer. Handling methods should be chosen such that they maintain fruit quality and avoid delays.

3. Time period between harvesting and consumption: Delays between harvesting and cooling or processing may result in direct losses (due to water loss and decay) and indirect losses (decrease in flavor and nutritional quality).

FRUIT MATURITY, RIPENING, AND QUALITY RELATIONSHIPS

Maturity at harvest is the most important factor that determines storage life and final fruit quality. Immature fruits are more subject to shriveling and mechanical damage, and are of inferior quality when ripened. Overripe fruits are likely to become soft and mealy with insipid flavor soon after harvest. Fruits picked either too early or too late in the season are more susceptible to physiological disorders and have a shorter storage life than those picked at mid-season. With very few exceptions (e.g., pears, avocados, and bananas), all fruits reach their best eating quality when allowed to ripen on the tree or plant. In general, fruits become sweeter, more colorful, and softer as they mature. However, some fruits are usually picked mature but unripe so that they can withstand the postharvest handling system when shipped long distances. Most currently used maturity indices are based on a compromise between those indices that would ensure the best eating quality to the consumer and those that provide the needed flexibility in transportation and marketing. Fruits can be divided into two groups: (1) nonclimacteric fruits that are not capable of continuing their ripening process once removed from the plant, and (2) climacteric fruits that can be harvested mature and ripened off the plant. Following are examples of each group:

Group 1: Berries (e.g., blackberry, cranberry, raspberry, strawberry), grape, cherry, citrus (grapefruit, lemon, lime, orange, mandarin, tangerine), pineapple, pomegranate, lychee, tamarillo, loquat.

Group 2: Apples, pear, quince, persimmon, apricot, nectarine, peach, plum, kiwifruit, avocado, banana, plantain, mango, papaya, cherimoya, sapodilla, sapota, guava, passion fruit.

Fruits of the first group (nonclimacteric) produce very small quantities of ethylene and do not respond to ethylene treatment except in terms of degreening (degradation of chlorophyll) in citrus fruits and pineapples. Fruits in Group 2 (climacteric) produce much larger quantities of

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ethylene in association with their ripening and exposure to ethylene treatment will result in faster and more uniform ripening.

Maturity indices used vary among fruits and often among cultivars within a specific fruit, but generally include one or several (combination indices) of the following: fruit size and shape, overall color, ground color of the skin, flesh color, flesh firmness, soluble solids content, starch content, acidity, and internal ethylene concentration. Listed below are some examples of maturity indices that can be used for selected fruits:

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COMPOSITION AND COMPOSITIONAL CHANGES DURING RIPENING

The flesh of young developing fruits contains very little sugar, and the large amounts of starch, acid, and tannins make them inedible. As the fruits approach maturity, flesh cells enlarge considerably, and sugar content increases while starch, acid, and tannin contents decrease. In addition, certain volatile compounds develop, giving the fruit its characteristic aroma. Chlorophyll degradation (loss of green color) and synthesis of carotenoids (yellow and orange colors) and anthocyanins (red and blue colors) takes place both in the skin and the flesh with fruit ripening. All fruits soften as they ripen due to changes in cell wall composition and structure. In this section, we present an overview of fruit constituents in relation to quality and changes after harvest.

1. CARBOHYDRATES

Carbohydrates are the most abundant and widely distributed food component derived from plants. Fresh fruits vary greatly in their carbohydrate content, with the general range between 10 to 25%. The structural framework, texture, taste, and food value of a fresh fruit is related to its carbohydrate content. Sucrose, glucose, and fructose are the primary sugars found in fruits (Table 1.1), and their relative importance varies among commodities. Sugars are found primarily in the cytoplasm and range from about 0.9% in limes to 16% in fresh figs. Sucrose content ranges from a trace in cherries, grapes, and pomegranate to more than 8% in ripe bananas and pineapple. Such variation influences taste since fructose is sweeter than sucrose, and sucrose is sweeter than glucose. Starch occurs as small granules within the cells of immature fruits. Starch is converted to sugar as the fruit matures and ripens. Other polysaccharides present in fruits include cellulose, hemicellulose, pectin, and lignin, which are found mainly (up to 50%) in cell walls and vary greatly among commodities. These large molecules are broken down into simpler and more soluble compounds as a result of fruit softening. The transformation of insoluble pectins into soluble pectins is controlled, for the most part, by the enzymes pectinesterase and polygalacturonase. Reduced activities of these two enzymes have been associated with reduced juiciness and poor texture in peaches that were ripened after storage at 1 0C for more than 3 weeks.

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2. PROTEINS

Fruits contain less than 1% protein (vs. 9 to 20% protein in nuts such as almond, pistachio, and walnut). Changes in the level and activity of proteins resulting from permeability changes in cell membranes may be involved in chilling injury. Enzymes, which catalyze metabolic processes in fruits, are proteins that are important in the reactions involved in fruit ripening and senescence. Some of the enzymes important to fruit quality include the following:

3. LIPIDS

Lipids constitute only 0.1 to 0.2% of most fresh fruits, except for avocados, olives, and nuts. However, lipids are very important because they make up the surface wax that contributes to fruit appearance and the cuticle that protects the fruit against water loss and pathogens. Lipids are also important constituents of cell membranes. The degree of fatty acid saturation establishes membrane flexibility, with greater saturation resulting in less flexibility. Desaturation of fatty acids can occur upon chilling in chilling-sensitive fruits; in which case membranes undergo a

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phase change (liquid crystalline to solid gel) at chilling temperatures resulting in disruption of normal metabolism.

4. ORGANICACIDS

Organic acids are important intermediate products of metabolism. The Krebs (TCA) cycle is the main channel for the oxidation of organic acids in living cells and it provides the energy required for maintenance of cell integrity. Organic acids are metabolized into many constituents, including amino acids, which are the building blocks of proteins. Most fresh fruits are acidic with a pH range of 3 to 5. Some fruits, such as lemons and limes, contain as much as 2 to 3% of their total fresh weight as acid. Total titratable acidity, specific organic acids present and their relative quantities, and other factors influence the buffering system and affect pH. Acid content usually decreases during ripening due to the utilization of organic acids during respiration or their conversion to sugars. Malic and citric acids are the most abundant in fruits (Table 1.2), except grapes (tartaric acid is the most important in most cultivars) and kiwifruits (quinic acid is the most abundant).

5. PIGMENTS

Pigments, which are the chemicals responsible for skin and flesh colors, undergo many changes during the maturation and ripening of fruits. These include the following:

1. Loss of chlorophyll (green color), which is influenced by pH changes, oxidative conditions, and chlorophyllase activity

2. Synthesis and revelation of carotenoids (yellow and orange colors)

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3. Development of anthocyanins (red, blue, and purple colors), which are fruit specific (Table 1.3) Beta-carotene is a precursor to vitamin A and thus is important in terms of nutritional quality. Carotenoids are very stable and remain intact in fruit tissues even when extensive senescence has occurred. Anthocyanins occur as glycosides in the cell sap. They are water soluble, unstable, and are readily hydrolyzed by enzymes to free anthocyanins, which may be oxidized by phenoloxidases to give brown oxidation products.

6 .PHENOLIC COMPOUNDS

Total phenolic content is higher in immature than in mature fruits and typically ranges between0.1 and 2 g/100 g fresh weight. Fruit phenolics include chlorogenic acid, catechin, epicatechin, leucoanthocyanidins, flavonols, cinnamic acid derivatives, and simple phenols. Chlorogenic acid (ester of caffeic acid) occurs widely in fruits (Figure 1.1) and is the main substrate involved in enzymatic browning of cut or otherwise damaged fruit tissues when exposed to air. Enzymatic browning occurs due to the oxidation of phenolic compounds and is mediated, in the presence of O2, by the enzyme polyphenoloxidase (PPO). The initial product of oxidation is usually O-quinone, which is highly unstable and undergoes polymerization to yield brown pigments of higher molecular weight. Polyphenoloxidase catalyzes the following two reactions:

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Normally phenolic compounds are separated from the PPO enzyme in the intact cells of plant tissue. Once the tissue is damaged, PPO and the phenolic compounds that it acts on are decompartmentalized and the above-mentioned reactions occur, leading to tissue browning. The extent of brown discoloration depends upon the total amount of phenolic compounds in the tissue and the level of PPO activity. Differences among cultivars of a given species in terms of browning potential in response to mechanical injury are related to the variation in the total phenolic content and PPO activity of the cultivar. Differences in phenylalanine ammonia lyase (PAL) enzyme activity influence phenolic content. Astringency is directly related to phenolic content, and it usually decreases with fruit ripening because of conversion of astringent phenolic compounds from the soluble to the insoluble nonastringent form. Loss of astringency occurs via (1) binding or polymerization of phenolics, (2) change in molecular size of phenolics, and (3) change in the hydroxylation pattern of phenolic compounds. There is a strong positive relationship between phenolic content and antioxidant capacity of fruits and their products.

7. VOLATILES

Volatiles are responsible for the characteristic aroma of fruits. They are present in extremely small quantities (<100mg/g fresh wt.). The total amount of carbon involved in the synthesis of volatiles is <1% of that expelled as CO2. The major volatile formed in climacteric fruits is ethylene (50 to 75% of the total carbon content of all volatiles). Ethylene does not have a strong

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aroma and does not contribute to typical fruit aromas. Volatile compounds are largely esters, alcohols, acids, aldehydes and ketones (low-molecular weight compounds). Very large numbers of volatile compounds have been identified in fruits and more are identified as advances in separation and detection techniques and gas chromatographic methods are made. However, only a few key volatiles are important for the particular aroma of a given fruit. Their relative importance depends upon threshold concentration (which can be as low as 1 ppb), potency, and interaction with other compounds.

8. VITAMINS

The water-soluble vitamins include vitamins C, thiamin, riboflavin, niacin, vitamin B6, folacin, vitamin B12, biotin, and pantothenic acid. Fat-soluble vitamins include vitamins A, D, E, and K. Fat soluble vitamins are less susceptible to postharvest losses. Ascorbic acid is most sensitive to destruction when the commodity is subjected to adverse handling and storage conditions. Losses are enhanced by extended storage, higher temperatures, low relative humidity (which may cause wilting), physical damage, and chilling injury. Postharvest losses in vitamins A and B are usually much smaller than losses in vitamin C. They are, however, susceptible to degradation at high temperatures in the presence of oxygen.

9.MINERALS

Important fruit minerals include base-forming elements (Ca, Mg, Na, and K) and acid-forming elements (P, Cl, S). Minerals present in microquantities include Fe, Cu, Co, Mn, Zn, I, and Mo. High nitrogen content is often associated with reduced soluble solids content, lower acidity, and increased susceptibility to physiological disorders in fruits.

Potassium is the most abundant mineral found in fruits. It most often occurs in combination with organic acids. High potassium content is often associated with increased acidity and improved color of fruits. Calcium is the second most important mineral constituent and is associated primarily with the cell wall. High calcium contents reduce CO2and C2H4 production rates, delay ripening, reduce the incidence of physiological disorders, and extend the storage life of apples and other fruits. Calcium deficiency has been associated with several physiological disorders such as bitter pit of apples. Magnesium is a component of the chlorophyll molecule, which is responsible for the intensity of green color in fresh produce. Phosphorus is a constituent of

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cytoplasmic and nuclear proteins and plays a major role in carbohydrate metabolism and energy transfer. High phosphorus content may result in decreased acidity in some fruits.

BIOLOGICAL FACTORS INVOLVED IN POSTHARVEST DETERIORATION OF FRUITS

1. RESPIRATION

Respiration is the process by which stored organic materials (carbohydrates, proteins, and fats) are broken down into simple end products with a release of energy. Oxygen (O2) is used in this process,and carbon dioxide (CO2) is produced. The loss of stored food reserves in the commodity during respiration hastens senescence as the reserves that provide energy to maintain the commodity’s living status are exhausted. For the consumer, food value (energy value) is gone, flavor quality is reduced, and sweetness, especially, is lost. Salable dry weight is also lost (especially important for commodities destined for dehydration). The energy released as heat, which is known as vital heat, affects postharvest technology considerations such as estimations of refrigeration and ventilation requirements. The rate of deterioration (degree of perishability) of fruits is generally proportional to their respiration rate (Table 1.4).

2. ETHYLENEP RODUCTION

Ethylene, the simplest of the organic compounds affecting the physiological processes of plants, is a natural product of plant metabolism and is produced by all tissues of higher plants and by some microorganisms. As a plant hormone, ethylene regulates many aspects of growth, development, and senescence and is physiologically active in trace amounts (less than 0.1 ppm). Ethylene biosynthesis starts with the amino acid methionine, which is energized by ATP to produceS -adenosyl methionine (SAM). The key enzyme in the pathway, ACC synthase, converts SAM to 1-aminocyclopropane-1-carboxylic acid (ACC), which is converted to ethylene by the action of ACC oxidase.

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Ethylene production rates, which depend on the fruit (Table 1.5), generally increase with maturity at harvest, physical injuries, disease incidence, increased temperatures up to 30oC, andwater stress. On the other hand, ethylene production rates by fresh fruits are reduced by storage atlow temperature and by reduced O2 (less than 8%) and elevated CO2 (above 1%) levels in the storage environment around the commodity.

3. TRANSPIRATION OR WATER LOSS

Water loss is the main cause of deterioration because it results not only in indirect quantitative losses (loss of salable weight) but also in losses in appearance (wilting and shriveling), textural quality (softening, flaccidity, limpness, and loss of crispness and juiciness), and nutritional quality. The dermal system (outer protective coverings) governs the regulation of water loss by the commodity. This system includes the cuticle, epidermal cells, stomata, lenticels, and trichomes (hairs). The cuticle is composed of surface waxes, cutin embedded in wax, and a layer of mixtures of cutin, wax, and carbohydrate polymers. The thickness, structure, and chemical composition of the cuticle vary greatly among commodities and among developmental stages of a given commodity. Transpiration rate is influenced by internal or commodity factors (morphological and anatomical characteristics, surface-to-volume ratio, surface injuries, and maturity stage) and external or environmental factors (temperature, relative humidity, air movement, and atmospheric pressure). Transpiration (evaporation of water from the plant tissues) is a physical process that can be controlled by applying treatments to the commodity (e.g., waxes and other surface coatings or wrapping with plastic films) or by manipulation of the environment (e.g., maintenance of high relative humidity and control of air circulation).

4. PHYSIOLOGICAL DISORDERS

The following physiological disorders occur in fruits:

1. Freezing injury when fruits are held below their freezing temperatures. The disruption caused by freezing usually results in immediate collapse of the tissues and total loss.

2. Chilling injury when fruits (mainly those of tropical and subtropical origin) are held at temperatures above their freezing point and below 5 to 15 ∞C depending on the commodity. This physiological injury is manifested in a variety of symptoms, which include surface and internal discoloration, pitting, water-soaked areas, uneven ripening or failure to ripen, off-flavor

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development, and accelerated incidence of surface molds and decay. A classification of fruits according to their sensitivity to chilling injury is shown in Figure 1.2.

3. Heat injury results from exposure to direct sunlight or to excessively high temperatures. Symptoms include surface scalding, uneven ripening, and excessive softening and desiccation.

4. Certain types of physiological disorders originate from preharvest nutritional imbalances such as calcium deficiency, causing bitter pit of apples.

5. Very low (<1%) oxygen and elevated (>20%) carbon dioxide concentrations can result in physiological breakdown of all fruits.

5. PHYSICAL DAMAGE

Various types of physical damage (surface injuries, impact bruising, and vibration bruising, etc.) are major contributors to deterioration. Mechanical injuries are not only unsightly but also accelerate water loss, stimulate higher respiration and ethylene production rates, and favor decay incidence.

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6 .PATHOLOGICAL BREAKDOWN

Decay is one of the most common or apparent causes of deterioration. However, attack by many microorganisms usually follows mechanical injury or physiological breakdown of the commodity, which allow entry to the microorganism. In a few cases, pathogens can infect healthy tissues and become the primary cause of deterioration.

ENVIRONMENTAL FACTORS INFLUENCING DETERIORATION OF FRUITS

1. TEMPERATURE

Temperature is the most important environmental factor that influences the deterioration rate of harvested fruits. For each increase of 10∞ C (18∞F) above the optimum temperature, the rate of deterioration increases by two- or threefold. Exposure to undesirable temperatures results in many physiological disorders as mentioned above. Temperature also influences how ethylene, reduced oxygen, and elevated carbon dioxide levels affect the commodity. The growth rate of pathogens is greatly influenced by temperature and some pathogens, such as Rhizopus rot, are sensitive to low temperatures. Thus, cooling of commodities below 5∞C immediately after harvest can greatly reduce Rhizopus rot incidence.

2. RELATIVE HUMIDITY

The rate of water loss from fruits depends upon the vapor pressure deficit between the commodity and the surrounding ambient air, which is influenced by temperature and relative humidity.

3. AIR MOVEMENT

Air circulation rate and velocity can influence the uniformity of temperature and relative humidity in a given environment and consequently rate of the water loss from the commodity.

4. ATMOSPHERIC COMPOSITION

Reduction of oxygen and elevation of carbon dioxide, whether intentional (modified or controlled atmosphere storage) or unintentional, can have a beneficial or harmful effect on deterioration. The magnitude of these effects depends upon commodity, cultivar, physiological

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age, O2and CO2 level, temperature, and duration of storage. A summary of current and potential use of controlled atmospheres to maintain the quality of fruits during transport and storage is given in Table 1.6.

5 .ETHYLENE

Ethylene is a natural plant hormone and its effect on harvested fruits can be desirable (degreening and ripening) or undesirable (abbreviated storage and softening). Ethylene effects are cumulative throughout the postharvest life of the fruit, and the magnitude of ethylene effects depends upon temperature, exposure time, and ethylene concentration. A concentration as low as 50 ppb ethylene enhances kiwifruit softening at 0∞C. Avocados and “Fuyu” persimmons are also very sensitive toethylene action; exposure to 1 ppm (or higher) ethylene increases chilling injury symptoms. Use of ethylene to degreen citrus fruits can accelerate their senescence and increase their susceptibility to decay-causing pathogens.

HARVESTING PROCEDURES

Harvesting methods, especially those involving a once-over procedure, may determine uniformity of maturity at harvest, which in turn influences quality of the fruit. Maturity also influences susceptibility of the fruit to water loss and mechanical injury. The harvesting system used and its management have a direct effect on incidence and severity of mechanical injuries. Such injuries can result in tissue browning, accelerated water loss, higher respiration and ethylene production rates, and increased decay incidence. Physical injuries may also induce some undesirable compositional changes, such as loss of ascorbic acid content and development of off-flavors. Management of the harvesting operation, whether manual or mechanical, can have a major impact on quality of the harvested fruits. Proper management procedures include selection of optimum time to harvest in relation to fruit maturity and climatic conditions, training and supervision of workers, and effective quality control.

POSTHARVEST HANDLING PROCEDURES

1. DUMPING

Fresh fruits should be handled with care throughout the postharvest handling system in order to minimize mechanical injuries. Dumping in water or in floatation tanks should be used for fruits that withstand wetting. If dry dumping systems are used, they should be well padded to reduce impact bruising. Also, a bin cover may be used to permit inverting the bin and to regulate the flow of fruits out of the bin.

2. WASHING

To clean fruit, water alone or with added cleaning agents and/or chlorine (typically 100 to 150ppm) may be used. The final rinse should be made with fresh, clean water. Following washing, removal of excess surface water may be necessary and this can be done by blotting rollers or by air flow over the fruits.

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3 .SORTING

Manual sorting is usually carried out to eliminate fruit exhibiting defects or decay. For some fruits, it may also be necessary to sort the fruit into two or more classes of maturity or ripeness (according to their color and firmness) before ripening or processing. Mechanical sorters, which operate on the basis of color, soluble solids, moisture, or fat content, are being implemented and may greatly reduce time and labor requirements.

4. SIZING

In some cases, sizing the fruits into two or more size categories may be required before processing. Sizing can be done mechanically on the basis of fruit dimension or by weight. Mechanical sizing can be a major source of physical damage to the fruit if the machines were not adequately padded and adjusted to the minimum possible fruit drop heights.

5. RIPENING

Ripening before processing may be required for certain fruits (e.g., avocado, banana, kiwifruit, mango, nectarine, papaya, peach, pear, persimmon, plum, and melons) that are picked immature. Ethylene treatment can be used to obtain faster and more uniform ripening. The optimum temperature range for ripening is 15 to 25∞C and within this range, the higher the temperature the faster the ripening. Relative humidity should be maintained between 90 and 95% during ripening. Although 10 ppm ethylene is sufficient to initiate ripening, a concentration of 20 to 100 ppm for at least 2 d is recommended for commercial application. Adequate air circulation within the room is important to ensure uniform distribution of ethylene. One method to achieve this is by forcing the ethylene-containing air through the fruit containers (forced-air ripening or pressure ripening). It is also important to avoid accumulation of carbon dioxide (produced by the commodity through respiration) above 1% in the ripening room since carbon dioxide counteracts ethylene effects. This can be accomplished by periodic air exchange (introduction of fresh air into the ripening room) or by using hydrated lime to absorb carbon dioxide.

6. INHIBITING ETHYLENE ACTION

Since July 2002, the ethylene-action inhibitor, 1-methylcyclopropene gas (1-MCP) under the trade name “SmartFresh” at concentrations up to 1 ppm was approved by the U.S. Environmental Protection Agency for use on apples, apricots, avocados, kiwifruit, mangoes, nectarines, papayas, peaches, pears, persimmons, plums, and tomatoes. The first commercial application has been on apples to retard their softening and scald development and extend their postharvest life. As more research is completed, the use of 1-MCP will no doubt be extended to several other commodities in the future.

7. COOLING

Cooling is utilized to remove field heat and lower the fresh fruit’s temperature to near its optimum storage temperature. Cooling can be done using cold water (hydrocooling) or cold air (forced-air cooling or pressure cooling). Highly perishable fruits, such as strawberries, bush berries, and apricots should be cooled to near 0∞C (32∞F) within 6 h of harvest. Other fruits should be cooled to their optimum temperature within 12 h of harvest.

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8 .STORAGE

Short-term or long-term storage of fresh fruits may be needed before processing to regulate theproduct flow and extend the processing season. A classification of fresh fruits according to their optimum storage temperature and potential storage life is shown in Table 1.7. In all cases, the relative humidity in the storage facility should be kept between 90 and 95%. To reduce decay, elevated CO2 (15 to 20%) may be added to the atmosphere within pallet covers for strawberries, bush berries, and cherries; sulfur dioxide (200 ppm) fumigation may be used on table grapes. There is a continuing trend toward increased precision in temperature and relative humidity management to provide the optimum environment for fresh produce during cooling, storage, and transport. Precision temperature management tools, including time–temperature monitors, are becoming more common in cooling and storage facilities. Several manufacturers have developed self-contained temperature and RH monitors and recorders, which are small and can be packed in a box with the product. Data are read by connecting these units to a personal computer with the appropriate software made by the manufacturer. Infrared thermometers are used to measure surface temperature of products from a distance in various locations within storage facilities. Electronic thermometers (with very thin, strong probes for fast response) are used for measuring product temperature during cooling, storage, and transport operations.

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FOOD SAFETY GUIDELINES

Over the past few years, food safety has become and continues to be the number one concern of the fresh produce industry. A training manual for trainers titled Improving the Safety and Quality of Fresh Fruits and Vegetable was published by the USFDA in November 2002 to provide uniform, broad-based scientific and practical information on the safe production, handling, storage, and transport of fresh produce. It is available electronically (in English and Spanish) at the following Internet site: http://www.jifsan.umd.edu/gaps.html.

FOOD SECURITY GUIDELINES

On March 19, 2003, The U.S. Food and Drug Administration (FDA) released food security guidance documents for food producers, processors, and transporters. These documents are available electronically at http://www.cfsan.fda.gov/~dms/secguid6.html and are voluntary recommendations from the FDA and not mandatory regulations. The goal is to help operators of food handling facilities identify preventive measures to minimize the security risks to their products.

KEYS TO SUCCESSFUL HANDLING OF FRESH FRUITS

1. MATURITY AND QUALITY

1. Harvest at the proper maturity stage that will result in the best eating quality.

2. Eliminate fruits with defects in the orchard or soon after delivery to the processing plant.

2. TEMPERATURE AND HUMIDITY MANAGEMENT PROCEDURES

1. Harvest during the cool part of the day.

2. Keep in the shade while accumulating fruits in the orchard.

3. Transport fruits to the processing plant as soon as possible after harvest and use refrigerated transport vehicles for distances that require more than a few hours.

4. Avoid delays at the processing plant. If delays cannot be avoided, cool and hold fruits at or near their optimum storage temperature until processed.

5. Maintain proper temperature and relative humidity during ripening of fruits requiring such treatment (with or without added ethylene).

3.PHYSICAL DAMAGE

1. Handle fruits with care during harvesting, hauling to the processing plant, and during handling operations within the plant.

2. Avoid drops, impacts, vibrations, and surface injuries of fruits throughout the handling system.

3. Use containers that would provide adequate protection of the commodity from physical injuries when stacked during temporary storage.

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4. SANITATION PROCEDURES

1. Sort out and properly discard decayed fruits.

2. Clean harvest containers, processing plant machinery, cooling and storage facilities, and

transit vehicles periodically with water, soap, and disinfectants.

5. EXPEDITED HANDLING

1. Reduce the time between harvest and cooling the fruits.

2. Avoid exceeding the fruit’s storage life, based on flavor quality, before processing.

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Chilling Injury

Chilling is an injury induced by low temperatures usually below 13° C and above 0° C (see table 1) Commodities typically sensitive to chilling include tropical, subtropical, warm-season, some temperate crops. Crops, susceptible to chilling injury often have a short storage life, as low temperatures cannot be used to slow deterioration and pathogen growth. Chilling injury may occur in the field, in transit or distribution, in retail or home refrigeration. The amount of injury a commodity experiences depends on three factors:

- Temperature

- Length of exposure

- Sensitivity of organ to chilling temperatures

It is thought that the primary cause of chilling injury is due to physical changes in membrane lipids. This membrane response leads to secondary responses, including:

1. Increased ethylene synthesis

2. Increased respiration rate

3. Increased membrane permeability

4. Reduction of photosynthesis

5. Slowing of protoplasmic streaming

6. Interference in energy production

7. Increase in activation energy

8. Alteration of cellular structure

These responses, if of short duration, are reversible and do not necessarily lead to observable symptoms. General symptoms of prolonged chilling of sensitive commodities are:

- Tissues discoloration (may not be visible, e.g. Avocados)

- Surface pitting (death of underlying cells with resulting collapse)

- Retardation or failure of ripening

- Wilting due to increased water loss, caused by disruption of epidermis

- Increased decay due to leakage of plant metabolites and entry point for microorganism, which encourage their growth

- Water- soaked tissues (e.g. pepper)

- Compositional changes (e.g. off flavor and texture)

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While there are a number of control strategies, it should be noted that not all are applicable to all commodities. To ameliorate or minimize chilling injury;

- Avoid storing susceptible cultivars at low temperature

- Temperature acclimation or modulation

- Preconditioning, stepwise cooling

- Alternating low and warm temperatures (intermittent warming)

- Commodity nutrition (Ca and P)

- Hypobaric storage

- High C02

- Waxing

- Chemicals / antioxidants (e.g., DPA-ethoxyquin, TBZ)

- Increased vapor loss

- Other treatments (e.g., pressure infiltration of Ca)

Factors affecting susceptibility to chilling are:

- Maturity at harvest (generally riper fruit is less susceptible)

- Cultural practices

- Climate during growing season (pre-harvest frost etc.)

- Produce size

- Harvesting practices

Chilling injury is a physiological dysfunction that affects mainly crops from the warmer areas of the world. Knowledge of the factors contributing to chilling injury can lead to techniques that reduce or avoid the problem.

Table 1: Examples of Fruits, Vegetables and Floriculture Products Susceptible To Chilling Injury

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Commodity

Recommended Minimum Storage Temperature (°C)

Potential Chilling Injury Symptoms

Anthurium

>13

- darkening and water-soaked appearance

Apple

0-7

- core or flesh browning, fermented flavor, spongy texture, susceptibility and symptoms vary with cultivar

Asparagus

2-4

- occurs primarily at the tips

- darkened and water

k d f ll d b b t i l ft t

Avocado

7-13

- darkening of vascular tissues,

- discoloration of flesh and skin

off flavors and odors abnormal ripening

Banana

>13

- green fruit: brown under peel discoloration.

- Ripe fruit: brown to black peel discoloration,

ff fl b l i i

Basil

7-10

- wilting, water-soaked appearance, darkening

Bean (snap)

7-10

- russeting, pitting

Cantaloupe

2-5

- pitting, surface decay

Cucumber

7-10

- pitting of surface, lenticel area affected first, followed by Fusahum and other rots

Eggplant

7-13

- scald-like browning, pitting, flesh browning, decay and loosening of capstems, Altemana rot

Grapefruit

10-15

- brown pitting of rind, watery breakdown of internal and external tissues fermented odour

Honeydew Melon

7-13

- water-soaking of the rind, softening, greying or browning, surface becomes soft and sticky resulting in increased decay

Lemon

10-14

- as for grapefruit, plus red blotch

Lime

9-12

- as for grapefruit

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Mango

>13

- greyish skin discolouration, pitting, uneven ripening, poor flavour, increased susceptibility to

Altemana rot

Okra

7-10

- pitting

Orange

2-5

- as for grapefruit

Orchid, cattleya

7-10

- discolouration of column first, then sepals and petals

Papaya

7-13

- pitting, olive or brown discolouration, abnormal i ripening I

Peach/Nectarine

-0.5-1

(critical temperature 2- 8)

- internal breakdown, mealiness, abnormal ripening, flesh browning or reddening

Pepper

7-13

-water-soaked appearance, sheet pitting, darkening, I predisposition to Alternaria and Botrytis

Pineapple

7-13

- flesh watery, followed by browning or blackening

Poinsettia

>13

- leaf drop, wilting

Potato

3-10

- mahogany browning, sweetening

Pumpkins/winter squash

10-15

- rot, primarily Alternaria.

Sweet potato

>13

- flesh discoloration, internal breakdown, increased decay, off- flavors, hard core when cooked

Tomato

- ripe - green

7-13 >13

- rubbery texture, watery flesh, irregular ripening.

- seed browning

Watermelon

10-15

- pitting, loss of flavor, fading of red color

Zucchini/summer

squash

5-10

- surface pitting, rapid decay

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Fruits juices, squash, cordials and nectars, fruit juice concentrate and powder, orange juice, apple juice.

Beverages

Production of fruit beverages on a commercial scale was practically unknown till about 1930, but since then it has gradually become an important industry. In tropical countries like India, fruit beverages provide delicious cold drinks during the hot summer. Due to their nutritive value they are becoming more popular than synthetic drinks which at present have a very large market in our country. Synthetic drinks contain only water (about 88%) and total carbohydrates (about 12%) and provide about 48 K-cal, whereas fruit based drinks contain vitamins (A, B and C:) and minerals (iron, calcium, etc.) and provide more calories. Thus, fruit-based drinks are far superior

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to many synthetic drinks. If synthetic preparations are replaced by fruit beverages, it would be a boon to the consumers as well as to the fruit growers.

Fruit beverages

Fruit beverages are easily digestible, highly refreshing, thirst-quenching, appetizing and nutritionally far superior to many synthetic and aerated drinks. They can be classified into two groups:

(A) Unfermented beverages: Fruit juices which do not undergo alcoholic fermentation are termed as unfermented beverages. They include natural and sweetened juices, RTS (ready-to-serve), nectar, cordial, squash, crush. syrup, fruit juice concentrate and fruit juice powder. Barley waters and carbonated beverages are also included in this group.

(8) Fermented beverages: Fruit juices which have undergone alcoholic fermentation by yeasts include wine, champaigne, port, sherry, tokay, muscat, perry, orange wine, berry wine, nira, and cider.

Preparation and preservation of unfermented fruit beverages:

The general process for the preparation and preservation of unfermented fruit beverages is as under:

(i) Selection of fruit: All fruits are not suitable because of difficulties in extracting the juice or because the juice is of poor quality. The variety and maturity of the fruit and locality of cultivation influence the flavour and keeping quality of its juice. Only fully ripe fruits are selected. Over ripe and green fruits. if used, adversely affect the quality of the juice.

(ii) Sorting and washing: Diseased, damaged or decayed fruits are rejected or trimmed. Dirt and spray residues of arsenic, lead, etc., are removed by washing with water or dilute hydrochloric acid (1 part acid: 20 parts water).

(iii) Juice extraction: Generally juice is extracted from fresh fruit by crushing and pressing them. Screw-type juice extractors, basket presses or fruit pulpers are mostlyused. The method of extraction differs from fruit to fruit because of differences in their structure and composition. Before prersinq most fruits are crushed to facilitate the extraction. Some require heat processing for breaking up the juice-containing tissues. In case of citrus fruits, the fruit is cut into halves and the juice extracted by light pressure in a juice extractor or by pressing the halves in a small wooden juice extractor. Care should be taken to remove the rind of citrus fruits completely otherwise it makes the juice bitter. Finally, the juice is strained through a thick cloth or a sieve to remove seeds. All equipment used in the preparation of fruit juices and squashes should be rust and acid proof. Copper and iron vessels should be strictly avoided as these metals react with fruit acids and cause blackening of the product. Machines and equipments made of aluminium, stainless steel, etc., can be used. During extraction juices should not be unnecessarily exposed to air as it will spoil the colour, taste and aroma and also reduce the vitamin content.

(iv) Deaeration: Fruit juices contain some air, most of which is present on the surface of the juice and some is dissolved in it. Most of the air as well as other gases are removed by subjecting

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the fresh juice to a high vacuum. This process is called deaeration and the equipment used for the purpose is called a deaerator. Being a very expensive method, it is not used in India at present.

(v) Straining or filtration: Fruit juices always. contain varying amounts of suspended matter consisting of broken fruit tissue, seed, skin, gums, pectic substances and protein in colloidal suspension: Seeds and pieces of pulp and skin which adversely affect the quality of juice, are removed by straining through a thick cloth or sieve. Removal of all suspended matter improves the appearance but often results in disappearance of fruity character and flavour. The present practice is to let fruit juices and beverages retain a cloudy or pulpy appearance to some extent. In case or grape juice, apple juice and lime juice cordial, however, a brilliantly clear appearance is preferred.

(vi) Clarification: Complete removal of all suspended material from juice, as in lime juice cordial, is known as clarification which is closely related to the quality, appearance and flavour of the juice. The following methods of clarification are used:

(A) Settling: The juice is stored in a carboy or barrel, after adding a chemical preservative to ensure that it does not undergo fermentation, e.g., lime juice is stored for 3 to 6 months for settling with the addition of 700 ppm sulphur dioxide. Colloidal pectins, gums, proteins, mucilaginous solids settle down and the juice is syphoned off for further treatment. However, the process is very slow.

(B) Filtration: Filtration is necessary to remove completely all fine and colloidal suspensions. In this process, the juice, after straining, is forced through a filtering medium which may be cotton pulp, wood pulp, woven fibre cloth, etc. The colloidal suspension tends to clog the filter, hence a filter aid is used to reduce clogging. The most important filter aids are supercel, kieselguhr, spanish clay and bentonite, which are added to the extent of 0.1-0.2 per cent. However, a filter aid may impart an unpleasant taste to the juice, therefore, these should be used with caution. Recently, china clay has been demonstrated to be a good filter aid.

(C) Freezing : The pasteurized juice kept in a carboy is frozen at -18°C and thereafter stored for 4 to 7 days at room temperature. This is a costly method and is used to some extent only for clarification of grape juice.

(D) Cold storage : This is generally used for grape juice. The juice is stored at -2 to - 3°C for one month during which the suspended matter settles down and clear juice can then be taken out.

(E) High temperature : The juice is heated at 82°C for about a minute when the colloidal material coagulates and settles down. After cooling rapidly, the juice is mixed with a filter aid and passed through a filter press. Pomegranate juice is prepared by this method.

(F) Chemicals: Fining agents such as gelatin, albumen, casein, and a mixture of tannin and gelatin, are also used for clarification.

(a) Gelatin: It is used for apple and cashew apple juices. On addition of gelatin solution, the colloids present in the juice coagulate and form a flocculent precipitate which settles down. The precipitation is due to electrostatic action between the positively charged gelatin particles and Negatively charged colloids in the juice.

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(b) Albumen: Solid albumen available in the market is dissolved in warm water to make a 2 per cent solution. A solution of egg-white may also be used. The albumen solution is mixed with the juice, which is heated to about 91°C to ensure complete coagulation of albumen.

(e) Casein: Addition of hydrochloric acid to skimmed milk precipitates casein which is thoroughly washed with water to remove traces of acid, dried and powdered. It is then dissolved in a little liquor ammonia and the solution diluted 10 to 20 times with water and then boiled to re- move all traces of ammonia. It is again diluted with water to give a 2 per cent solution which is mixed with the juice. In 24 hours the acids in the juice precipitate the casein which settles down along with other colloidal particles.

(d) Mixture of tannin and gelatin: The tannin-gelatin method is very widely used for clarifying fruit juices. The quality of gelatin to be added is determined by carrying out a preliminary laboratory test. Sufficient tannin is added to minimize the bleaching action of gelatin. About 42 g of tannin and 85 g of gelatin are generally required for every 455 litres of juice. The juice is well stirred, the tannin solution is added to it with stirring and the gelatin solution is then added. The treated juice is allowed to stand undisturbed for 18 to 24 hours to let the suspended matter coagulate and settle down. The clear juice is then syphoned off carefully without disturbing the sediment. In case of lime juice addition of 213 g of tannin and 283 g of gelatin )er 2500 litres of juice, preserved by the addition of about 350 ppm of sulphur dioxide, immediately after extraction, gives a sparkling clear product. The colloidal matter settles down completely in 4 to 6 days and the clear supernatant juice can be syphoned off and used for preparation of cordial.

(G) Enzymes: Soluble pectins in the juice are responsible for keeping in suspension other materials such as hemicellulose. When the pectin is destroyed by adding pectic enzyme preparations, e.g., Pectinol and Filtragol, it settles down and during this process also carries down other materials. After filtering, the clear juice is heated to about 77°C for 30 minutes to stop the enzymatic action otherwise the juice becomes cloudy again.

(vii) Addition of sugar : All juices are sweetened by adding sugar, except those of grape and apple. Sugar also acts as preservative for the flavor and colour and prolongs the keeping quality. Sugar-based products can be divided into three groups on the basis of sugar content:

(a) Low Sugar - 30 per cent sugar or below,

(b) Medium sugar - Sugar above 30 and below 50 per cent,

(c) High Sugar - 50 per cent sugar and above.

Sugar can be added directly to the juice or as a syrup made by dissolving it in hot water, clarifying by addition/ of a small quantity of citric acid or few drops of lime juice and filtering.

(viii) Fortification: Juices, squashes, syrups, etc., are sometimes fortified with vitamins to enhance their nutritive value, to improve taste, texture or colour and to replace nutrients lost in processing. Usually ascorbic acid and beta-carotene (water-soluble form) are added at the rate of 250 to 500 mg and 7 to 10 mg per litre, respectively. Ascorbic acid acts as an antioxidant and beta-carotene imparts an attractive orange colour. For a balanced taste some acids are added. Citric acid is often used for all types of beverages and phosphoric acid for cola type of drinks.

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(ix) Preservation: Fruit juices, RTS and nectars are preserved by pasteurization but sometimes chemical preservatives are used. Squashes, crushes and cordials are preserved only by adding chemicals. In the case of syrup, the sugar concentration is sufficient to prevent spoilage. Fruit juice concentrates are preserved by heating, freezing or adding chemicals.

(x) Bottling : Bottles are thoroughly washed with hot water and filled leaving 1.5-2.5 cm head space. They are then sealed either with crown corks (by crown corking machine) or with caps (by capping machine).

Unfermented Beverages

(1) Juices: Juices are of two types -

(a) Natural juice (pure juice): It is the juice, as extracted from ripe fruits, and contains only natural sugars.

(b) Sweetened juice: It is a liquid product which contains at least 85 per cent juice and 10 per cent total soluble solids. Pure fruit juices, such as apple juice and orange juice are commercially manufactured in several countries. Apple juice is generally bottled while other juices are canned. The techniques for preparation of various fruit juices are given as follows:

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(ii) Blended juices

Sometimes two or more juices are mixed to yield a well-balanced, rightly flavoured, highly palatable and refreshing drink. Juices are blended so as to utilize a too sweet fruit (grape), a bitter fruit (grapefruit), too acidic or tart fruits (sour lime, sour plum, galgal, sour cherry, etc.), bland and insipid tasting fruits like pear or apple, and strongly flavoured fruits (guava and banana). Some of the common commercial blends of juice are:

(1) Grape (97%) and lime (3%)

(2) Grape (50%) and orange (50%}

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(3)Orange (50-75%) and grapefruit (25-50%)

(4) Apple (97%) and lime (3%)

(5) Apple (74%) and grapefruit (25%) + 1% sugar

(6) Apple (50-75%) and pineapple (25-50%) + 1% sugar

(7) Apple (37%) and plum (62%) + 1% sugar

(2) Ready-to-serve (RTS)

This is a type of fruit beverage which contains at least 10 per cent fruit juice and 10 per cent total soluble solids besides about 0.3 per cent acid. It is not diluted before serving, hence it is known as ready-to-serve (RTS).

Before undertaking the preparation of beverages, it is necessary to know the techniques of extraction of pulp/juice from various fruits used for RTS, nectar. squash, syrup, etc. The extraction techniques for some fruits have been described earlier and for some other fruits are as under.

For preparing the beverages the total soluble solids in the pulp/juice and its acidity are first determined and then requisite amounts of sugar and citric acid dissolved in water are added for adjustment of TSS and acidity. In homes, RTS can be prepared by using the following recipes:

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(3) Nectar

This type of fruit beverage contains at least 20 per cent fruit juice/pulp and 15 per cent total soluble solids and also about 0.3 per cent acid. It is not diluted before serving. Commercially, nectar (with 13% TSS and 0.3% acid) can be prepared by using the following recipes standardized by Department of Horticulture, N.D. University of Agriculture and Technology, Faizabad.

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For preparing the above beverages the total soluble solids and total acid present in the pulp/juice are first determined and then the requisite amounts of sugar and citric acid dissolved in water are added for adjustment of TSS and acidity. In homes, nectar can be prepared by employing the following recipes:

Process: Similar to that of preparation of RTS.

(4) Cordial

It is a sparkling, clear, sweetened fruit juice from which pulp and other insoluble. Substances have been completely removed. It contains at least 25 per cent juice and 30 per cent TSS. It also contains about 1.5 per cent acid and 350 ppm of sulphur dioxide. This is very suitable for blending with wines. Lime and lemon are suitable for making cordial. In homes, cordial can be prepared using the following recipe:

Lime/Lemon juice - 1.0 litre

Sugar - 1.25 kg

Water - 1.0 litre

Potassium metabisulphite - 2.0 g

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This is a type of fruit beverage containing at least 25 per cent fruit juice or pulp and 40 to 50 per cent total soluble solids, commercially. It also contains about 1.0 per cent acid and 350 ppm sulphur dioxide or 600 ppm sodium benzoate. It is diluted before serving.

Mango, orange and pineapple are used for making squash commercially. It can also be prepared from lemon, lime, bael, guava, litchi, pear, apricot, pummelo, musk melon, papaya, etc., using potassium metabisulphite (KMS) as preservative, or from jamun, passion-fruit, peach, phalsa, plum, mulberry, raspberry, strawberry, grapefruit, etc., with sodium benzoate as preservative. In homes, squashes can be prepared according to the following recipes:

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(5) Crush

This type of fruit beverage contains at least 25 per cent fruit juice or pulp and 55 per cent total soluble solids. It is more or less similar to squash, contains about 1.0 per cent acid and is diluted before serving.

(6) Syrup

This type of fruit beverage contains at least 25 per cent fruit juice or pulp and 65 per cent total soluble solids. It also contains 1.3-1.5 per cent acid and is diluted before serving. Fruits like phalsa, aonla, jamun, pomegranate, grape, lemon, orange and sometimes ginger can be used for the preparation of syrup. It is also prepared from extracts of rose, sandal, almond, etc. Syrups (with 68% TSS and 1.3% acid) can be prepared commercially by using the following recipes:

Syrup from extracts

Syrups containing extracts of rose, sandal, kewra, mint, khus, almond, etc. are very popular. The preparation of some of these syrups is described below

(i) Rose syrup: Clean rose petals (100 g) are soaked overnight in about 200 mi. of water, then well rubbed, heated for about 5 minutes and strained. The syrup is prepared by using 100 ml of rose extract, 700 g of sugar, 10 g of citric acid and 250 ml of water. Sometimes raspberry red colour and rose water are also added.

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(ii) Sandal syrup: Sandalwood powder (50 g) is soaked overnight in about 250 ml of water, then heated for about 5 minutes and strained. The syrup is prepared by using the extract, 1.3 kg of sugar, 400 ml of water, and 10 g of citric acid. Sometimes Kewra essence is also added.

(iii) Almond syrup: Almond kernels (50 g) are soaked in 200 ml of hot water for some time, the loosened skin is removed and the kernels are ground with 10 g of cardamom (small) and the juice is strained. Syrup is prepared by using above extract, 1.3 kg of sugar, 10 g of citric acid and 350 ml of water. Sometimes kewra or rose essence is added as required.

Synthetic syrups

Heavy sugar syrup of 70-75 per cent strength is used as the base of all synthetic syrups and they are flavoured and coloured with artificial essence/flavours and colours. They never contain fruit pulp/juice. A large proportion of these syrups can, however, be replaced by real fruit juices, squashes and syrups which are more nutritious. Large quantities of synthetic syrups (orange, lemon, pineapple, raspberry,strawberry, khus, kewra, etc.) are manufactured and sold in various countries. These can be prepared by using 1.5 kg of sugar, 500 ml of water and 15 g of citric acid. Different colours and flavours are added as required. Among colours, orange red, lemon yellow, green, raspberry red, etc., are mostly used, while artificial essence/flavours of rose, kewra, orange, pineapple, strawberry, lemon etc are added as flavouring substances.

(7)Fruit Juice Concentrates

A fruit juice from which water has been mostly removed by heating or freezing is known as concentrate. Carbonated beverages are prepared from this. They contain pure juice with at least 32 per cent total soluble solids. The major advantages of concentrates are :

(i) Reduced weight and bulk compared to juice result in economy in packaging, storage and transport.

(ii) The whole crop of fruits is fully utilized during peak season, thus helping to stabilize the price.

(iii) The product can be used as base material for making various food and beverage formulations.

Problems with concentrates

(i) Fermentation is not prevented,

(ii) Non-enzymatic browning occurs, and

(iil] Gel formation takes place.

In some countries, concentrates of pure fruit juices particularly of orange, apple, pineapple and grape are highly popular. The major methods deployed for production of fruit and vegetable concentrates are : (i) freezing and mechanical evaporation: (ii) low-temperature vacuum evaporation; and (iii) high-speed high temperature evaporation.

(8) Fruit juice powder

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Fruit juice can be converted into a free-flowing, highly hygroscopic powder by puffdrying, freeze drying, vacuum drying, spray drying or drum drying. The powder has the advantage of long shelf-life and is soluble in cold water. But during the drying process much of the characteristic fresh flavour is lost, which is compensated for by adding to the juice powder natural fruit flavour in powder form. Reconstitution of the powder mixture yields fuIl strength fruit juice drink. Techniques have been standardized by Central Food Technological Research Institute, Mysore, for preparation of powder from mango, orange, lemon, guava, passion-fruit, banana, avocado, tomato, etc.

(9) Barley water

Fruit beverage which contains at least 25 per cent fruit juice, 30 per cent total soluble solids and 0.25 per cent barley starch is known as barley water. It also contains about 1.0 per cent acid. Barley water is prepared from citrus fruits such as lime, lemon, grapefruit and orange and of these lime and lemon are mostly used. It is prepared by using about 1 litre of fruit juice, 2.0 kg of sugar, 15 g of barley flour and 1.3 litre of water. Essence and potassium metabisulphite (as in case of cordial) may be added if desired.

(10) Carbonated beveragesThe use of fruit juices in the preparation of carbonated drinks is practically unknown in India. Mostly, artificially flavoured drinks which have no nutritive value are prepared by this method. The use of fruit juices would increase the nutritive value of carbonated beverages.The juice can be directly carbonated, or can be stored as such, or in the form of concentrate for carbonation whenever necessary. Carbonated beverages can keep well for about a week without addition of any preservative. If the products are to be kept for a longer period, 0.05 per cent sodium benzoate must be added. For example, while preparing carbonated orange syrup; juice, sugar and citric acid in the ratio of 1: 1.55:0.044 should be used. For carbonation, 42 to 56 g of this prepared syrup is filled in 285 to 340 g bottles. In the same manner syrups of pineapple, lime, lemon, etc. can be prepared. Lemonade, orangeade, ginger, strawberry, lime juice, are examples of carbonated beverages.

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Jam

Jam is a product made by boiling fruit pulp with sufficient sugar to a reasonably thick consistency, firm enough to hold the fruit tissues in position, Apple, pear, sapota (chiku), apricot, loquat, peach, papaya, karonda, carrot, plum, straw- berry, raspberry, mango, tomato, grapes and muskmelon are used for preparation of jams. It can be prepared from one kind of fruit or from' two or more kinds. Commercial jams such as tutti-frutti can be prepared from pieces of fruit, fruit scraping and pulp adhering to cores of fruits which are available in plenty in canning factories. Jam contains 0.5-0.6 per cent acid and invert sugar should not be more than 40 per cent. In the home it can be prepared by using the recipes as given in the table.

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Problems in jam production

(i) Crystallization: The final product should contain 30 to 50 per cent invert sugar. If the percentage is less than 30, cane sugar may crystallize out on storage and if it is more than 50 the jam will become a honey-like mass due to the formation of small crystals of glucose. Corn syrup or glucose may be added along with cane sugar to avoid crystallization.

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(ii) Sticky or gummy jam: Because of high percentage of total soluble solids, jams tend to become gummy or sticky. This problem can be solved by addition of pectin or citric acid, or both.

(iii) Premature setting: This is due to low total soluble solids and high pectin content in the jam and can be prevented by adding more sugar. If this cannot be done a small quantity of sodium bicarbonate is added to reduce the acidity and thus prevent precoagulation.

(iv)Surface graining and shrinkage: This is caused by evaporation of moisture during storage of jam. Storing in a cool place can reduce it.

(v) Microbial spoilage: Sometimes moulds may spoil the jam during storage but they are destroyed if exposed to less than 90 per cent humidity. Hence, jams should be stored at 80 per cent humidity. Mould growth can also prevented by not sealing the filled jar and covering the surface of jam with a disc of waxed paper because mould does not grow under open conditions as rapidly as in a closed space. It is also advisable to add 40 ppm sulphur dioxide in the form of KMS. In the case of cans, sulphur dioxide should not be added to the jam as it causes blackening of the internal surface of the can. Yeasts are not a serious problem due to the high concentration of sugar.

Pectin-properties-theories –Olsen’s theory,Spencer’s theory , Hinton’s theory, Fibril theory.

Pectin

Pectin is a structural heteropolysaccharide contained in the primary cell walls of terrestrial plants. It was first isolated and described in 1825 by Henri Braconnot.[2] It is produced commercially as a white to light brown powder, mainly extracted from citrus fruits, and is used in food as a gelling agent particularly in jams and jellies. It is also used in fillings, medicines, sweets, as a stabilizer in fruit juices and milk drinks, and as a source ofdietary fiber. Pectins, also known as pectic polysaccharides, are rich in galacturonic acid. Several distinct polysaccharides have been identified and characterised within the pectic group. Homogalacturonans are linear chains of α-(1-4)-linked D-galacturonic acid. Substituted galacturonans are characterized by the presence of saccharide appendant residues (such as D-xylose or D-apiose in the respective cases of xylogalacturonan and apiogalacturonan) branching from a backbone of D-galacturonic acid residues. Rhamnogalacturonan I pectins (RG-I) contain a backbone of the repeating disaccharide: 4)-α-D-galacturonic acid-(1,2)-α-L-rhamnose-(1. From many of the rhamnose residues, sidechains of various neutral sugars branch off. The neutral sugars are mainly Dgalactose, L-arabinose and D-xylose, with the types and proportions of neutral sugars varying with the origin of pectin. Another structural type of pectin is rhamnogalacturonan II (RG-II), which is a less frequent complex, highly branched polysaccharide. Rhamnogalacturonan II is classified by some authors within the group of substituted galacturonans since the rhamnogalacturonan II backbone is made exclusively of Dgalacturonic acid units.Isolated pectin has a molecular weight of typically 60–130,000 g/mol, varying with origin and extraction conditions.In nature, around 80 percent of carboxyl groups of galacturonic acid are esterified with methanol. This proportion is decreased to a varying degree during pectin extraction. The ratio of esterified to nonesterified galacturonic acid determines the behavior of pectin in food applications.

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This is why pectins are classified as high- vs. low-ester pectins (short HM vs. LM-pectins), with more or less than half of all the galacturonic acid esterified. The non-esterified galacturonic acid units can be either free acids (carboxyl groups) or salts with sodium, potassium, or calcium. The salts of partially esterified pectins are called pectinates, if the degree of esterification is below 5 percent the salts are called pectates, the insoluble acid form, pectic acid. Some plants such as sugar beet, potatoes and pears contain pectins with acetylated galacturonic acid in addition to methyl esters. Acetylation prevents gel-formation but increases the stabilising and emulsifying effects of pectin. Amidated pectin is a modified form of pectin. Here, some of the galacturonic acid is converted with ammonia to carboxylic acid amide. These pectins are more tolerant of varying calcium concentrations that occur in use. To prepare a pectingel, the ingredients are heated, dissolving the pectin. Upon cooling below gelling temperature, a gel starts to form. If gel formation is too strong, syneresis or a granular texture are the result, whilst weak gelling leads to excessively soft gels. In high-ester pectins at soluble solids content above 60% and a pH-value between 2.8 and 3.6, hydrogen bonds and hydrophobic interactions bind the individual pectin chains together. These bonds form as water is bound by sugar and forces pectin strands to stick together. These form a 3-dimensional molecular net that creates the macromolecular gel.

The gelling-mechanism is called a low-water-activity gel or sugar-acid-pectin gel.In lowester pectins, ionic bridges are formed between calcium ions and the ionised carboxyl groups of the galacturonic acid. This is idealised in the so-called “egg box-model”. Lowester pectins need calcium to form a gel, but can do so at lower soluble solids and higher pH-values than high-ester pectins. Amidated pectins behave like low-ester pectins but need less calcium and are more tolerant of excess calcium. Also, gels from amidated pectin are thermo-reversible; they can be heated and after cooling solidify again, whereas conventional pectin-gels will afterwards remain liquid. High-ester pectins set at higher temperatures than low-ester pectins. However,gelling reactions with calcium increase as the degree of esterification falls. Similarly, lower pH-values or higher soluble solids (normally sugars) increase gelling speed. Suitable pectins can therefore be selected for jams and for jellies, or for higher sugar confectionery jellies.

The pectic substances are also of considerable importance in the firming of canned tomatoes, apples, and other fruits by calcium salts. Canned tomatoes which are graded A and which therefore bring the highest price must be relatively firm, yet full-colored. However, during ripening, tomatoes pass through this period rapidly, soften, and on canning undergo considerable maceration and shredding. The addition of small amounts of calcium salts to the pack increases the firmness of the fruit. Calcium salts can be added to the dip or placed in the can with the salt. Calcium chloride is permitted in the United States at a level of 0.07 per cent; and salts such as calcium citrate, sulfate, or phosphate may be used at equivalent levels calculated on the basis of calcium ion. This level has no effect on the flavor of the fruit but produces a marked effect on the firmness. The method is also used widely for firming both canned and frozen sliced apples as well as baked apples. It has also been shown to be effective.

Chemically, pectin consists of the partial methyl esters of polygalacturonic acid and their salts (sodium, potassium, calcium and ammonia), with a molecular weight of up to 150,000 Daltons. Pectin is obtained by aqueous extraction of the appropriate edible plant materials, mainly from citrus peel and apple pomace, followed by a selective precipitation using alcohol or salts. The raw materials used contain a large amount of pectin with superior quality and are available in sufficient quantities to make the manufacturing process more cost effective. Pectin is usually

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classified according to the degree of methoxylation (DM). The degree of methoxylation is expressed as a percentage of esterified galacturonic acid units to total galacturonic acid units in the molecule of pectin. Pectin produced by the normal extraction process contains more than 50% of methoxyl groups and is classified as high methoxyl (HM) pectin.

HM pectin

Modification of the extraction process, or continued acid treatment, will yieldconventional low methoxyl (LMC) pectin with less than 50% methoxyl groups.

LMC pectin

Commercial classification

Pectin is classified according to the degree of methoxylation (DM) as high methoxyl pectin (DM >50) and low methoxyl pectin (DM <50). The degree of methoxylation influences the properties of pectin, especially the solubility and the gel forming characteristics.

HM pectins are capable of forming gels in aqueous systems with high contents of soluble solids and low pH values.

LM pectins are characterised by their ability to form gels in the presence of bivalent salts, normally Ca++ ions, in systems with low solids content and a wide pH range.

Pectin classification

Pectin is classified by International Numbering System as E440(i) for high methoxyl pectin and conventional low methoxyl pectins and E440(ii) for amidated low methoxyl pectin.

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Sources of production

Apples, guavas, quince, plums, gooseberries, oranges and other citrus fruits, contain large amounts of pectin, while soft fruits like cherries, grapes and strawberries contain small amounts of pectin.

The main raw-materials for pectin production are dried citrus peel or apple pomace, both by-products of juice production. Pomace from sugar-beet is also used to a small extent. From these materials, pectin is extracted by adding hot dilute acid at pH-values from 1.5 – 3.5. During

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several hours of extraction, the protopectin loses some of its branching and chain-length and goes into solution. After filtering, the extract is concentrated in vacuum and the pectin then precipitated by adding ethanol or isopropanol.

An old technique of precipitating pectin with aluminium salts is no longer used (apart from alcohols and polyvalent cations; pectin also precipitates with proteins and detergents).

Alcohol-precipitated pectin is then separated, washed and dried. Treating the initial pectin with dilute acid leads to low-esterified pectins. When this process includes ammonium hydroxide, amidated pectins are obtained. After drying and milling, pectin is usually standardised with sugar and sometimes calcium-salts or organic acids to have optimum performance in a particular application. Worldwide, approximately 40,000 metric tons of pectin are produced every year. The main use for pectin (vegetable agglutinate) is as a gelling agent, thickening agent and stabilizer in food. The classical application is giving the jelly-like consistency to jams or marmalades, which would otherwise be sweet juices. For household use, pectin is an ingredient in gelling sugar (also known as "jam sugar") where it is diluted to the right concentration with sugar and some citric acid to adjust pH. In some countries, pectin is also available as a solution or an extract, or as a blended powder, for home jam making. For conventional jams and marmalades that contain above 60% sugar and soluble fruit solids, high-ester pectins are used. With low-ester pectins and amidated pectins less sugar is needed, so that diet products can be made.Pectin can also be used to stabilize acidic protein drinks, such as drinking yogurt, and as a fat substitute in baked goods. Typical levels of pectin used as a food additive are between 0.5 – 1.0% - this is about the same amount of pectin as in fresh fruit. In medicine, pectin increases viscosity and volume of stool so that it is used against constipation and diarrhea. Until 2002, it was one of the main ingredients used in Kaopectate a drug to combat diarrhoea, along with kaolinite. Pectin is also used in throat lozenges as a demulcent. In cosmetic products, pectin acts as stabilizer. Pectin is also used in wound healing preparations and specialty medical adhesives, such ascolostomy devices. Also, it is considered a natural remedy for nausea.

Functional properties of pectin

It is the hydrocolloid character of pectin which makes it such important and versatile adduct in certain food system. Most important raw material for the production of commercial pectin is apple pomace, peels of various citrus fruits. Apple pomace have low content of pectin [15%] and on the other hand lime peel have to the extend of 50%.

Degree of methoxylation of pectin

It has been found that galactouronic acid unit of pectin is partially esterified with methyl group. The DM of pectin decides the sped of gelation and pectins with high DM also set at higher temperature which will influence their end use. The pectin having DM of more than 50% is called as high methoxyl [HM] pectin and pectin with DM of less than 50% is called as low methoxyl [LM] pectin. HM have quite specific gelling property as it require high soluble solids i.e. above 55% and low pH. LM are able to form thermo- reversible gels and need Ca ions for gel formation.

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Measurement of grades of pectin

Initially pectin was graded as per SAG value but now a days it is being estimated as breaking strength and as internal strength as being measured by pektionometer and Stevens- LFRA Texture Analyser respectively.

Pectin and gel formation

Pectin is readily soluble in water when the concentration of soluble solids is below 25%. As the sugar or total solids [TS %] content increases through processing, the available free moisture is removed and pectin will dehydrate. The precipitated macromolecule will form a lattice through the gel and being negatively charged, pectin molecules in solution will repel one another. By lowering the pH [increasing the hydrogen ion concentration], the repulsion effect will be reduced and gel

Theories of gel formation

Jelly formation is due to the precipitation of pectin rather than its swelling. Only when the pectin, acid, sugar and water are in definite equilibrium range, the precipitation of pectin takes place. The rate of precipitation depends on

Concentration of pectin in solution

Constitution of pectin

pH of the pectin solution

Concentration of sugar in solution

Temperature of mixture

Fibril theory

According to Cruess, when sugar is added to pectin solution, it destabilizes the pectin water equilibrium and the pectin conglomerates forming a network of fibrils holds the sugar solution in the inter fibrillar spaces. The strength of the jelly depends on the strength of fibrils, their continuity and rigidity. The greater the amount of pectin, greater number of fibrils formed and the network will be more continue and dense. The firmness of network depends on concentration of sugar and acidity. Increasing amount of sugar reduces the of water to be supported by pectin firbrils, lower amount of sugar can be compensated by using additional amount of pectin. The fibrils of the pectin become tough in the presence of acid and thus hold sugar. If a larger amount of acid is present, fibrils lose their elasticity with the result that the jelly becomes syrupy, due to hydroxylation of pectin. If acid is present in smaller amount, a weak fibril is formed which is unable to support the sugar solution. It can be made up by adding more pectin. Ultimately, the maximum amount of acid which can be added to the pectin solution, without any undesirable effect, is determined by the degree of decomposition of the pectin.

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Spencer’s theory

Pectin particles are negatively charged. A pectin solution is most stable at the neutral pH . Thus increase in acidity or alkanity decreases the stability of pectin solution. In jelly formation , sugaracts as a precipitating gent, and the presence of acid helps it. Some salts also help in the precipitation of pectin, while others hinder t according to their capacity to increase or decrease the stability. Thus, more the acid present lesser will be the sugar requirement.

Olsen’s theory

If pectin is taken to be a negatively charged hydrophilic colloid, the following may be assumed.

Sugar acts as dehydrating agent, which disturbs the equilibrium existing between water and pectin.

Sugar does not dehydrate the pectin micelles instantaneously, but requires the time to bring about an equilibrium

If the negative charge on pectin is reduced, with the help of H+ concentration, pectin precipitates and form a network of insoluble fibers provided that the sugar is present in sufficient concentration.

The rate of hydration and precipitation of pectin increases with the addition of acid upto an optimum of about pH 2.0, in direct proportion to H+ concentration

As the system reaches an equilibrium, the jelly strength becomes the maximum

Salt and other components which cause a change in the ultimate jelly strength of the system, may function either by changing the rate of gelation or by affecting the ultimate structure f the jelly or by combination of both

Hinton’s theory

It s based upon the assumption that pectins are complex mixtures of variables composition. According to it, gelations of pectin are a type of coagulation in which the coagulated particles forma continuous network. It is only the non ionized, and not the ionized pectin, which enters into jelly formation. To form a jelly, therefore, the concentration of non ionized pectin must exceed a certain saturation limit, which varies with the concentration of total solids in the mixture.

Strength of Pectin Jellies

Quantity of pectin : the larger the amount of pectin present, the higher is the jelly strength

Quantity of acid : the larger the amount of acid presents, the lower the pH and higher is the jelly strength.

Quantity of salts : Jelly strength is affected by the presence of salt as also by the temperature of gelation and the tie elapsing between the additions of sugar and pouring of equally into containers

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Quantity of sugar : the higher the sugar concentration, the greater is the jelly strength

Temperature of gelation: more jelly strength is obtained when sugar + pectin is heated upto 21 to 100 °C

Jelly and Marmalades – Jelly- Difference between Jam and Jelly-Processing of Jelly-End point determination-Failure of Jellies to set- Cloudy or foggy Jellies- Formation of crystals- Syneresis. & Marmalades-what is a marmalade-types-Jam marmalade-Jelly marmalade- Problem in marmalade making.

Jelly

A jelly is a semi-solid product prepared by boiling a clear, strained solution of pectin containing fruit extract, free from pulp, after the addition of sugar and acid. A perfect jelly should be transparent, well-set, but not too stiff, and should have the original flavour of the fruit. It should be of attractive colour and keep its shape when removed from the mould. It should be firm enough 'to retain a sharp edge but tender enough to quiver when pressed. It should not be gummy, sticky or syrupy or have crystallized sugar. The product should be free from dullness, with little or no syneresis (weeping), and neither tough nor rubbery. According to their pectin and acid contents:

1. Rich in pectin and acid: Sour and crab apple, grape, sour guavas, lemon, oranges (sour), plum (sour), jamum.

2. Rich in pectin but low in acid: Apple (low acid varieties), unripe banana, sour cherry, fig (unripe), pear, ripe guava, peel of orange and grapefruit.

3. Low in pectin but rich in acid: Apricot (sour), sweet cherry, sour peach, pineapple and strawberry.

4. Low in pectin and acid: Ripe apricot, peach (ripe), pomegranate, rasp berry, strawberry and any other over-ripe fruit.

In the home it can be prepared by using following recipes:

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Important considerations in jelly making

Pectin, acid, sugar (65%), and water are the four essential ingredients. Pectin test and determination of end-point of jelly formation are very important for the quality of the jelly.

(A) Pectin

Pectin substances present in the form of calcium pectate are responsible for the firmness of fruits. Pectin is the most important constituent of jelly. It is a commercial term for water soluble pectinic acid which under suitable conditions forms a gel with sugar and acid. In the early stage of development of fruits, the pectic substance is a water-insoluble protopectin which is converted into pectin by the enzyme protopectinase during ripening of fruit. In over-ripe fruits, due to the presence of pectic methyl esterase (PM E) enzyme, the pectin gets largely converted to pectic acid which is water-insoluble. This is one of the reasons that both immature and overripe fruits are not suitable for making jelly and only ripe fruits are used. The setting of pectin is also dependent upon the pH and sugar concentration. Stiffness of the gel increases with increasing concentration of pectin up to a certain point beyond which the addition of more pectin has little effect. Too little pectin gives a soft syrup instead of gel. Pectin tends to keep the sugar from crystallizing by acting as a protective colloid, but is not effective when the concentration of sugar is 70 per cent or more. The jellying power of fruit pectin depends upon the amount of pectin used as well as its degree of polymerization and acetyl content. The amount of pectin extracted varies with the method of extraction, the ripeness of the fruit, the quantity of water added for extracting the juice and the kind of fruit. Usually about 0.5-1. 0 per cent of pectin of good quality in the extract is sufficient to produce good jelly. If the pectin content is higher a firm and tough jelly is formed and if it is less the jelly may fail to set.

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Determination of pectin content : The pectin content of the strained extract is usually determined by one of the following two methods.

(i) Alcohol test: This method, involving precipitation of pectin with alcohol, is outlined below: One teaspoonful of strained extract is taken in a beaker and cooled, and 3 teaspoonfuls of methylated spirit are poured gently down the side of the beaker which is rotated for mixing and allowed to stand for a few minutes.

(a) If extract is rich in pectin, a single, transparent lump or clot will form. An equal amount of sugar is to be added to the extract for preparation of jelly.

(b) If extract contains a moderate amount of pectin, the clot will be less firm and fragmented. Three-fourths the amount of sugar is to be added.

(c) If extract is poor in pectin, numerous small granular clots will be seen. One-half the amount of sugar is added.

(ii) Jelmeter test : The jelmeter is held in the left hand with the thumb and forefinger. The bottom of the jelmeter tube is closed with the little finger. The strained extract is poured into the jelmeter with a spoon, held in the right hand, till it is filled to the brim. While still holding the jelmeter, the little finger is removed from the bottom end and the extract is allowed to flow or drip for exactly one minute, at the end of which the finger is replaced. The reading of the level of extract in the jelmeter is noted. This figure indicates how many parts of sugar are to be added to one part of juice.

(B) Acid

The jellying of extract depends on the amount of acid and pectin present in the fruit. Of the three acids citric, malic and tartaric found in fruits, tartaric acid gives the best results.The.final jelly should contain at least 0.5 per cent (preferably 0.75%) but not more than 1 per cent total acids because a larger quantity of acid may cause syneresis.

pH of extract : Jelly strength increases with the increase in pH until optimum is reached. Further addition of acid decreases the jelly strength. The optimum pH for a jelly containing 1 per cent pectin is approximately 3.0, 3.2 and 3.4 for 60, 65 and 70 per cent TSS, respectively. The pH of the jelly can be controlled by (i) adjusting pH of extract with acid/alkali, and (ii) adding a suitable buffer. Fruits also contain salts like sodium citrate, sodium potassium tartrate, etc., which have buffering action and help to control pH. In general, the optimum pH value for jelly is 3.2.

(C) Sugar

This essential constituent of jelly imparts to it sweetness as well as body. If the concentration of sugar is high, the jelly retains less water resulting in a stiff jelly, probably because of dehydration.

Inversion of sugar : When sugar (sucrose) is boiled with an acid, it is hydrolyzed into dextrose and fructose, ths degree of inversion depending on the pH and duration of boiling. Because of partial inversion of the sucrose, a mixture of sucrose, glucose and fructose are found in the jelly.

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This mixture is more soluble in water than sucrose alone and hence the jelly can hold more sugar in solution without crystallization.

(D) Judging of end-point

Boiling of jelly should not be prolonged, because excessive boiling results in a greater inversion of sugar and destruction of pectin. The important point to remember is that it is the fruit extract which requires boiling and not the added sugar. If a jelly is cooked for a prolonged period, it may become gummy, sticky, syrupy and deteriorate in colour and flavour. The end-point of boiling can be judged in the following way:

i) Sheet or flake test: A small portion of jam is taken out during boiling, in a spoon or wooden ladle and cooled slightly. It is then allowed to drop. If the product falls off in the form of a sheet or flakes instead of flowing in a continuous stream or syrup, it means that the end-point has been reached and the product is ready, otherwise, boiling is continued till the sheet test is positive.

(ii) Drop test: A drop of the concentrated mass is poured into a glass containing water. Settling down of the drop without disintegration de- notes the end-point.

(iii) Temperature test: Asolution containing 65 per cent total soluble solids boils at 105°C. Heating of the jelly to this temperature would automatically bring the concentration of solids to 65 per cent. This is the easiest way to ascertain the endpoint

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Problems in jelly making : The most important difficulties that are experienced are as follows:

1. Failure to set: This may be due to :

(i) Addition of too much sugar : It results in a syrupy or highly soft jelly which can be corrected by addition of sufficient quantity of fresh, strained extract rich in pectin.

(ii) Lack of acid or pectin: Lack of acid or pectin, or of both, in the fruit used or insufficient cooking of the fruit slices resulting in inadequate extraction of pectin and acid.

(iii) Cookirig below the end-point : If the cooking is stopped before the percentage of total soluble solids reaches 65, the jelly may remain syrupy and highly soft.

(iv) Cooking beyond the end-point : Jelly becomes tough due to overconcentration. This usually happens when the juice is rich in both acid and pectin and enough sugar has not been added. If acid is in excess, the pectin breaks down resulting in formation of a ropy syrup or a jelly with waxy consistency.

(v) Prolonged cooking: In the presence of acid the coagulating property of pectin is destroyed if it is heated for a long time, hence prolonged heating should be avoided.

2. Cloudy or foggy jellies: It is due to the following reasons:

(i) Use of non-clarified juice or extract.

(ii) Use of immature fruits: Green, immature fruits contain starch which is insoluble in the juice and therefore, gives it a cloudy appearance.

(ili) Over-cooking: Such jellies are gummy or sticky on account of their high viscosity and do not become clear after pouring into containers.

(iv) Over-cooling: If the jelly is cooled too much, it becomes viscous and sometimes, lumpy and is always almost cloudy.

(v) Non-removal of scum : The jelly becomes cloudy when the scum is not removed before pouring.

(vi) Faulty pouring: When jelly is poured into containers from a grea height, some air gets trapped in the form of bubbles and makes the jelly opaque. Hence the pouring vessel should not be held more than about 2.5 em away from the top of the container.

(vii) Premature gelation : Excess of pectin in the extract causes prerna ture gelation with the result that air may get trapped in the jelly and thus make it opaque. It can be avoided by :

(a) Heating the solution to the boiling point and immediately pouring it into containers so as to reduce the time of contact between pectin, acid and boiling sugar;

(b) Using low concentration of sugar;

(c) Using a slow-setting pectin; and

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(d) Not using acid during cooking and instead putting a concentrated solution of acid in the container prior to pouring the cooked juice.

3. Formation of crystals:

It is due to addition of excess sugar and also to overconcentration of jelly.

4. Syneresis or weeping of jelly:

The phenomenon of spontaneous exudation of fluid from a gel is called syneresis or weeping and is caused by several factors: .

i) Excess of acid : It causes breakdown of the jelly structure by hydrolysis or decomposition of pectin. It occurs more in tender jellies and can be prevented by mixing either some quantity of juice low in acid or more of pectin, so that a larger quantity of sugar can be added which helps in reducing the acidity and increasing the volume of jelly.

(ii) Insufficient pectin : This results in the formation of a pectin network which is not sufficiently dense and rigid to hold the sugar syrup.

(iii) Premature gelation : This causes breaking of the pectin network during the pouring of jelly into containers and thus the jelly becomes weak and remains broken.

(v) Fermentation: Though a high percentage of sugar (65%) prevents ordinary fermentation, it can takes place in jelly if syneresis occurs. Storage of jelly in a damp place, even if covered with a seal of paraffin wax, favours the growth of mould. The growth may be due to several reasons: (a) not covering the jelly properly, (b) not pouring sufficiently hot paraffin wax so as to kill the moulds and bacteria present on the surface of jelly, and (c) breaking of paraffin wax seal. Hermetically sealable glass jars and cans are used to avoid this problem.

Marmalade

This is a fruit jelly in which slices of the fruit or its peel are suspended. The term is generally used for products made from citrus fruits like oranges and lemons in which shredded peel is used as the suspended material. Citrus marmalades are classified into

(i) jelly marmalade, and (ii) jam marmalade.

(1) Jelly marmalade: The following combinations give good quality of jelly marmalade:

(i) Sweet orange (Malta) and khatta or sour orange (Citrus aurantium) in the ratio of 2: 1 by weight. Shreds of Malta orange peel are used.

(ii) Mandarin orange and khatta in the ratio of 2: 1 by weight. Shreds of Malta orange peel are used.

(iii) Sweet orange (Malta) and galgal (Citrus iimonia) in the ratio of 2: 1 by weight. Shreds of Malta orange peel are used.

(2) Jam marmalade : The method of preparation is practically the same as that for jelly marmalade. In this case the pectin extract of fruit is not clarified and the whole pulp is used.

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Sugar is added according to the weight of fruit, generally in the proportion of 1:1. The pulp-sugar mixture is cooked till the TSS content reaches 65 per cent.

Problems in marmalade making

Browning during storage is very common which can be prevented by addition of 0.09 g of KMS per kg of marmalade and not using tin containers. KMS dissolved in a small quantity of water is added to the marmalade while it is cooling. KMS also eliminates the possibility of spoilage due to moulds.

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Fruit preserves and candied fruits-What are fruit preserves?-Preparation of fruits preserves-problems in making; Candied fruits-Preparation of candied fruits; Glazed fruit-preparation. & Glazed fruit- preparation, Crystallized fruit-preparation-problems in preparation of preserves and candied fruit.

Preserve

A mature fruit/vegetable or its pieces impregnated with heavy sugar syrup till it becomes tender and transparent is known as a preserve. Apple, pear, mango, cherry, karonda, strawberry, pineapple, papaya, etc., can be used for making preserves. In the home they can be prepared using 1 kg of fruit, 1 liter of water and 1 kg of sugar. A little quantity of acid (citric or tartaric) is added during the preparation to prevent crystallization of the syrup.

General considerations

Cooking of fruit in syrup is difficult because the syrup has to be maintained at a proper consistency so that it can permeate the whole fruit without causing it to shrink or toughen. Cooking directly in syrup causes shrinking of fruit and reduces absorption of sugar. Therefore, the fruit should be blanched first to make it soft enough to absorb water, before steeping in syrup. However, highly juicy fruits may be cooked directly.

Fruits may be cooked in syrup by three processes as given below:

(i) Rapid process: Fruits are cooked in low-sugar syrup. Boiling is continued with gentle heating until the syrup becomes sufficiently thick. Soft fruits such as strawberries and raspberries, 'which require very little boiling for softening, unlike hard fruits like apples, pears, and peaches, which require prolonged heating, can be safely cooked in heavy syrup. Rapid boiling should, however, be avoided as it makes the fruit tough, especially when heating is done in a large shallow pan with only a small quantity of syrup. The final concentration of sugar should not be less than 68 per cent which corresponds to a boiling point of 106°C. This is a simple and cheap process but the flavour and colour of the product are lost considerably during boiling.

(ii) Slow process : The fruit is blanched until it becomes tender. Sugar, equal to the weight of fruit, is then added to the fruit in alternate layers and the mixture allowed standing for 24 hours. During this period, the fruit gives out Water and the sugar goes into solution, result in a syrup containing 37-38 per cent total soluble solids. Next day the syrup is boiled after removal of fruits to raise its strength to about 60 per cent total soluble solids. A small quantity of citric or tartaric acid (1 to 1.5 g per kg sugar) is also added to invert a portion of the cane sugar and thus prevent crystallization. The whole mass is then boiled for 4-5 minutes and kept for 24 hours. On the third day, the strength of syrup is raised to about 65 per cent, total soluble solids by boiling. The fruit is then left in the syrup for a day. Finally, the strength of the syrup is raised to 70 per cent total soluble solids and the fruits are left in it for a week. The preserve is now ready and is packed in containers. In practice, the number of steps may be varied.

(iii) Vacuum process : The fruit is first softened by boiling and then placed in the syrup which should have 30-35 per cent total soluble solids. The fruit- syrup blend is then transferred to a

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vacuum pan and concentrated under reduced pressure to 70 per cent total soluble solids. Preserves made by this process retain the flavour and colour of the fruit better than by the other two methods. In all these processes, the fruit is kept covered with syrup during cooking as well as afterwards otherwise it will dry up and the quality of the product would be affected. The product should be cooled quickly after the final boiling to prevent discolouration during storage. The fruits are drained free of syrup and filled in dry containers or glass jars. Freshly prepared boiling syrup containing 68 per cent total soluble solids is then poured into the jars/containers which are then sealed airtight. In commercial scale production, however, it is better to sterilize the cans to eliminate any possibility of spoilage of product during storage.

Candied fruits/vegetables

A fruit/vegetable impregnated with cane sugar or glucose syrup, and subsequently drained free of syrup and dried, is known as candied fruit/vegetable. The most suitable fruits for candying are aonla, karonda, pineapple, cherry, papaya, apple, peach" and peels of orange, lemon, grapefruit and citron, ginger, etc. Pineapple cores, which are a waste product in the canning of pineapples, can be candied directly without any preliminary treatment. There is scope for developing this useful byproduct.

F.P.O.specifications. The process for making candied fruit is 'practically similar to that for preserves. The only difference is that the fruit is impregnated with syrup having a higher percentage of sugar or glucose. A certain amount {25-30 percent} of invert sugar or glucose, viz. confectioners glucose (corn syrup, crystal syrup or commercial glucose), dextrose or invert sugar is substituted for cane sugar.The total sugar content of the impregnated fruit is kept at about 75 per cent to prevent fermentation. The syrup left over from the candying process can be used for candying another batch of the same kind of fruit after suitable dilution, for sweetening chutneys, sauces and pickles, and in vinegar making.

Glazed fruits and vegetables

Covering of candied fruits/vegetables with a thin transparent coating of sugar, which imparts them a glossy appearance, is known as glazing. The preparation of glazed fruits has been described by Cruess as under:

Cane sugar and water (2: 1 by weight) are boiled in a steam pan at 113- 114°C and the scum is removed as it comes up. Thereafter the syrup is cooled to 93°C and rubbed with a wooden ladle on the side of the pan when granulated sugar is obtained. Dried candied fruits are passed through this granulated portion of thesugar solution, one by one, by means of a fork, and then placed on trays in a warm dry room. They may also be dried in a drier at 49°C for 2-3 hours. When they become crisp, they are packed in airtight containers for storage.

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Crystallized fruits/vegetables

Candied fruits/vegetables when covered or coated with crystals of sugar, either by rolling in finely powdered sugar or by allowing sugar crystals to deposit on them from a dense syrup are called crystallized fruits. The candied fruits are placed on a wire mesh tray which is placed in a deep vessel. Cooled syrup (70 per cent total soluble solids) is gently poured over the fruit so as to cover it entirely. The whole mass is left undisturbed for 12 to 18 hours during which a thin coating of crystallized sugar is formed. The tray is then taken out carefully from the vessel and the surplus syrup drained off. The fruits are then placed in a single layer on wire mesh trays and dried at room temperature or at about 49°C in driers.

Problems in preparation of preserves and candied fruits

(i) Fermentation: It is due to low concentration of sugar used in the initial stages of preparation of preserves. Sometimes fermentation also occurs during storage due to low concentration of sugar and insufficient cooking. This can be prevented by boiling the product at suitable intervals, by adding the required quantity of sugar and by storage in a cool and dry place.

(ii) Floating of fruits in jar : It is mainly due to filling the preserve without cooling and can be avoided by cooling the preserve prior to filling.

(iii) Toughening of fruit skin or peel: It may be due to inadequate blanching or cooking of fruits hence blanching till tender is necessary. Toughness may develop when cooking is done in a large shallow pan with only a small quantity of syrup.

(iv) Fruit shrinkage : Cooking of fruits in heavy syrup greatly reduces absorption of sugar and causes shrinkage. Therefore, fruits should be blanched first or cooked in low-sugar syrup.

(v) Stickiness: It may develop after drying or during storage due to insufficient consistency of the syrup, poor quality packing and damp storage conditions.

If candied and crystallized fruits are stored under humid conditions, they lose some of their sugar due to absorption of moisture from the air. Further, they become mouldy if they are not sufficiently dried and are packed in wet containers. There is considerable scope for exporting preserves and candies. Since these products are hygroscopic, water-proof packaging like metal and glass containers which are impermeable to water vapour should be used. Newer flexible plastic films would be cheap and highly effective. There is need for exploring the possibilities of utilizing various types of plastics for packaging of such products.

Chutneys-Preparation of chutney; Pickles-Types of Pickling-Pickling with salt-Dry salting-Brining.& Pickling with Vinegar and fermentation – Saurkraut -Role of lactic acid bacteria in pickling; Pickling with oil –pickling with mixture of salt, oil and spices-Problems/ spoilage in pickles.

Chutneys

A good quality chutney should be palatable and appetizing. Mango chutney is an important food product exported from India to many countries. Apple and apricot chutneys are also very popular in the country. The method of preparation of chutney is similar to that for jam except that spices,

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vinegar and salt are added. The fruits/vegetables are peeled, sliced or grated, or cut into small pieces and cooked in water until they become sufficiently soft. The quality of chutney depends to a large extent on its cooking which should be done for a long time at a temperature below the boiling point. To ensure proper thickening, cooking is done without a lid even though this results in some loss of volatile oils from the spices. Chopped onion and garlic are added at the start to mellow their strong flavours. Spices are coarsely powdered before adding. Vinegar extract of spices may be used instead of whole spices. Spice and vinegar are added just before the final stage of cooking, because prolonged boiling causes loss of some of the essential oils of spices and of vinegar by volatilization. In mango and apricot sweet chutneys, where vinegar is used in large quantity, the amount of sugar added may be reduced, because vinegar itself acts as a preservative. These chutneys are cooked to the consistency of jam to avoid fermentation.

Recipes for chutneys

Some common recipes for preparation of chutney are given below. However, it is always possible to go beyond a recipe, ignoring conventional tastes and creating something new.

.Sweet mango chutney

Mango slices or shreds 1 kg, sugar or gur 1 kg, salt 45 g, onions (chopped) 50 g, garlic (chopped) 15 g, ginger (chopped) 15 g, red chilli powder 10 g, black pepper, cardamom (large), cinnamon, cumin, aniseed (powdered) 10 g each, clove (headless) 5 numbers and vinegar 170 ml.

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Pickles

The preservation of food in common salt or in vinegar is known as pickling. It is one of the most ancient methods of preserving fruits and vegetables. Pickles are good appetizers and add to the palatability of a meal. They stimulate the flow of gastric juice and thus help in digestion. Several kinds of pickles are sold in the Indian market. Mango pickle ranks first followed by cauliflower, onion, turnip and lime pickles. These are commonly made in homes as well as commercially manufactured and exported. Fruits are generally preserved in sweetened and spiced vinegar, while vegetables are pre- served in salt. Pickling is the result of fermentation by lactic acid-forming bacteria" which are generally present in large numbers on the surface of fresh vegetables and fruits. These bacteria can grow in acid medium and in the presence of 8-10 per cent salt solution, whereas the growth of a majority of undesirable organisms is inhibited -. Lactic acid bacteria are most active at 30°C, so this temperature must be maintained as far as possible in the early stage of pickle making When vegetables are placed in brine, it penetrates into the tissues of the former and soluble material present in them diffuses into the brine by osmosis, The soluble

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material includes fermentable sugars and minerals. The sugars serve as food for lactic acid bacteria which convert them into lactic and other acids. The acid brine thus formed acts upon vegetable' tissues to produce the characteristic taste and aroma of pickle. In the dry salting method several alternate layers of vegetables and salt (20- 30 g of drysalt per kg vegetables) are kept in a vessel which is covered with a cloth and a wooden board and allowed to stand for about 24 hours. During this period, due to osmosis, sufficient juice comes out from the vegetables to form brine. Vegetables which do not contain enough juice (e.q., cucumber) to dissolve the added salt are covered with brine (steeping in a concentrated salt solution is known as brining). The amount of brine required is usually equal to half the volume of vegetables. Brining is the most important step in pickling. The growth of a majority of spoilage organisms is inhibited by brine containing 15 per cent salt. Lactic acid bacteria, which are salt-tolerant, can thrive in brine of 8-10 per cent strength though fermentation takes place fairly well even in 5 per cent brine. In a brine containing 10 per cent salt fermentation proceeds somewhat slowly. Fermentation takes place to some extent up to 15 per cent but stops at 20 per cent strength. It is, therefore, advisable to place the vegetables in 10 per cent salt solution for vigorous lactic acid fermentation. As soon as the brine is formed, the fermentation process starts and carbon dioxide begins to evolve. The salt content is now increased gradually, so that by the time the pickle is ready, salt concentration reaches 15 per cent. When fermentation is over, gas formation ceases. Under favourable conditions fermentation is completed in 7 to 10 days. When sufficient lactic add has been formed, lactic acid bacteria cease to grow and no further change takes place in the vegetables. However, precautions should be taken against spoilage by aerobic microorganisms in the presence of air pickle scum is formed which brings about putrefaction and destroys the lactic acid. Properly brined vegetables keep well in vinegar for a long time. At present, pickles are prepared with salt, vinegar, oil or with a mixture of salt, oil, spices and vinegar. These methods are discussed below:

(1) Preservation with salt

Salt improves the taste and flavour and hardness the tissues of vegetables and controls fermentation. Salt content of 15 per cent or above prevents microbial spoilage. This method of preservation is generally used only for vegetables which contain very little sugar and hence sufficient lactic acid cannot be formed by fermentation to act as preservative. However, some fruits like lime, mango, etc., are also preserved with salt. The preparation of some pickles is described below :

(i) Lime pickle: Lime 1 kg, salt 200 g, red chilli powder 15 g, cinnamon, cumin, cardamom (large) and black pepper (powdered) each 10 g, clove (headless) 5 numbers.

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(2) Preservation with vinegar

A number of fruits and vegetables are preserved in vinegar whose final concentration, in terms of acetic acid, in the finished pickle should not be less than 2 per cent. To prevent dilution of vinegar below this strength by the water liberated from the tissues, the vegetables or fruits are generally placed in strong vinegar of about 10 per cent strength for several days before pickling. This treatment helps to expel the gases present in the intercellular spaces of vegetable tissue. Vinegar pickles are the most important pickles consumed in other countries. Mango, garlic, chillies, etc., are preserved as such in vinegar. Some common recipes for vinegar pickles are given below:

(i) Papaya pickle: Peeled papaya pieces 1 kg, salt 100 g, red chilli powder 10 g, cardamom (large), cumin, black pepper (powdered) each 10 g, vinegar 750m.

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(3) Preservation with oil The fruits or vegetables should be completely immersed in the edible oil. Cauliflower, lime, mango and turnip pickles are the most important oil pickles. Methods of preparation of some oil pickles are given below :

Mango pickle: Mango pieces 1 kg, salt 150 g, fenugreek (powdered) 25 g, turmeric (powdered) 15 g, nigella seeds 15 g, red chilli powder 10 g, clove (headless) 8 numbers, black pepper, cumin, cardamom (large), aniseed (powdered) each 15 g, asafoetida 2 g, mustard oil 350 ml Gust sufficient to cover pieces).

(4) Preservation with mixture of salt, oil, spices and vinegar

Cauliflower pickle : Cauliflower (pieces) 1 kg, salt 150 g, ginger (chopped) 25g, onion (chopped) 50 g, garlic (chopped) 10 g, red chilli, turmeric, cinnamon, black pepper, cardamom (large), cumin, aniseed (powdered) each 15 g, cloves headless) 6 numbers, tamarind pulp 50 g, mustard (ground) 50 g, vinegar 150 ml, mustard oil 400 ml.

Sauerkraut

It is highly popular in some countries of Europe and in the U.S.A. Sauerkraut means acid cabbage. It is a clean, wholesome product with a characteristic. flavour, obtained by complete fermentation of shredded cabbage in the presence of 2-3 per cent salt. It contains not less than 1.5 per cent acid, expressed as lactic acid. Sauerkraut which has been re- brined in the process of canning or repacking contains not less than 1 per cent acid, expressed as lactic acid. Thus it is the product of lactic acid bacterial fermentation of cabbage under conditions favouring the production of lactic acid, acetic acid, alcohol and carbon dioxide. Sauerkraut stimulates the peptic glands and has mild laxative property which is due to the esters acetylcholine and lactylcholine formed during fermentation by lactic acid bacteria. White cabbage because of its low content of polyphenols is more suitable for making sauerkraut than winter cabbage.

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Problems in pickle making

(1) Bitter taste: Use of strong vinegar or excess spice or prolonged cooking of spices imparts a bitter taste to the pickle.

(2) Dull and faded product : This is due to use of inferior quality materials or insufficient curing.

(3) Shrivelling: It occurs when vegetables (e.g., cucumber) are placed directly in a very strong solution of sait or sugar or vinegar. Hence, a dilute solution should be used initially and its strength gradually increased.

(4) Scum formation: When vegetables are cured in brine, a white scum always form on the surface due to the growth of wild yeast. This delays the formation of lactic acid and also helps the growth of putrefactive bacteria which cause softness and slipperiness. Hence, it is advisable to remove scum as soon as it is formed. Addition of one per cent acetic acid helps to prevent the growth of wild yeast in brine, without affecting lactic acid formation.

(5) Softness and slipperiness: This very common problem is due to inadequate covering with brine or the use of weak brine: The problem can be solved by using a brine of proper strength and keeping the pickles well below the surface of the brine.

(6) Cloudiness: When the structure of the vegetable used in pickling, e.g., onion, is such that the acetic acid (vinegar) cannot penetrate deep enough into its tissues to inhibit the activity of bacteria and other microorganisms present in them, fermentation starts from inside the tissues; rendering the vinegar cloudy. This microbial activity can only be checked by proper brining. Cloudiness may also be caused by use of inferior quality vinegar or chemical reaction between vinegar and minerals.

(7) Blackening: It is due to the iron in the brine or in the process equipment reacting with the ingredients used in pickling. Certain microorganisms also cause blackening.

Sauces and Ketchups- what are sauces –difference between sauce and a ketchup-classification of sauces-thick and thin sauces-processing of Tomato sauce/ketchup-Preparation of soya sauce(thin sauce)-problems in making of sauces.

Sauces and Ketchups

There is no essential difference between sauce and ketchup. However, sauces are generally thinner and contain more total solids (minimum 30%) than ketchups (minimum 28%). Tomato, apple, papaya, walnut, soybean, mushroom, etc., are used for making sauces. Sauces are of two kinds: (i) Thin sauces of low viscosity consisting mainly of vinegar extract of flavouring materials like herbs and spices, and (ii) Thick sauces that are highly viscous. Sauces/ketchups are prepared from more or less the same ingredients and in the same manner as chutney, except that the fruit or vegetable pulp or juice used is sieved after cooking to remove the skin, seeds and stalks of fruits, vegetables and spices and to give a smooth consistency to the final product. However, cooking takes longer because fine pulp or juice is used. Some sauces develop a characteristics flavour and aroma on storing in wooden barrels. Freshly prepared products often have a raw and harsh taste and have, therefore, to be matured by storage. High quality sauces are

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prepared by maceration of spices, herbs, fruits and vegetables in cold vinegar or by boiling them in vinegar. The usual commercial practice is to prepare cold or hot vinegar extracts of each kind of spice and fruit separately, and then blend these extracts suitably to obtain the sauces which are then matured. Thickening agents are also added to the sauce to prevent sedimentation of solid particles. Apple pulp is commonly used for this purpose in India but starch from potato, maize, arrowroot (cassava) and sago are also used. A fruit sauce should be cooked to such a consistency that it can be freely poured without the fruit tissues separating out in the bottle. The colour of the sauce should be bright. Sauces usually thicken slightly on cooling. By using a funnel hot ketchup is filled in bottles leaving a 2 cm head space at the top and the bottles are sealed or corked at once. The necks of the bottles, when cold, are dipped in paraffin wax for airtight sealing. It is advisable to pasteurize sauces after bottling since there is always a danger of fermentation, especially in tomato and mushroom-based sauces. Other sauces are more acidic and less likely to ferment but should be pasteurized all the same. For this the bottles are kept in boiling water for about 30 minutes.Recipes for sauces (ketchups)

(1) Tomato sauce: See chapter on 'Tomato Processing'.

(2) Apple sauce

Apple pulp 1 kg, sugar 250 g, salt 10 g, onion (chopped) 200 g, ginger (chopped) 100 g, garlic (chopped) 50 g, red chilli powder 10 g, clove (headless) 5 numbers, cinnamon, cardamom (large), aniseed (powdered) 15 g each, vinegar/ acetic acid 50 ml and sodium benzoate 0.7 g per kg finished product.

(3) Plum sauce

Plum pulp 1 kg, sugar 100 g, salt 20 g, onion (chopped) 50 g, ginger (chopped) 25 g, garlic (chopped) 10 g, red chilli powder 10 g, clove (headless) 5 numbers, black pepper,cardamom (large), cinnamon (powdered) 10 g, each, vinegar 40 ml and sodium benzoate 0.7 g per kg sauce.

Black neck: Formation of a black ring in the neck of bottles is known as black neck. It is caused by the iron which gets into the product from the metal of the equipment and the cap/crown cork through the action of acetic acid. This iron coming into contact with tannins in spice forms ferrous tannate which is oxidized to black ferric tannate. Black neck can be prevented by:

(i) Filling hot sauce at a temperature not less than 85°C;

(ii) Leaving very little head space in bottles (the more the air the greater is the blackening);

(iii) Reducing contamination by iron, sources of iron being salt and metal equipment;

(iv) Partial replacement of sugar by corn syrup or glucose syrup which contain sulphur and prevent blackening;

(v) Addition of 100 ppm sulphur dioxide or 100 mg ascorbic acid;

(vi) Storing bottles in horizontal or inverted position to diffuse the entrapped air (02) throughout the bottle thus reducing its concentration in the neck sufficiently to prevent blackening;

(vii) Using cloves only after removing the flower/head.

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General methods of preparation and utilization of vinegar.

Fermented products from fruits and vegetables –Vinegar –types of vinegarmethods of vinegar production-Quick method-Orleans slow process- Generator process – problem in vinegar production.

Decomposition of carbohydrates by microorganisms or enzymes is called fermentation. Fermentation of food results in the production of organic acids, alcohol, etc., which not only help in preserving the food but may also produce distinctive new food products. The term fermentation has come to have somewhat different meanings as its underlying causes have become better understood. The derivation of the word fermentation signifies a gentle bubbling condition. The term was first applied to the production of wine more than a thousand years ago. The bubbling action was due to the conversion of sugar to carbon dioxide gas. When the reaction was defined following the studies of Gay-Lussac, fermentation came to mean the breakdown of sugar into alcohol and carbon dioxide. Pasteur later demonstrated the relationship of yeast to this reaction, and the word fermentation became associated with microorganisms, and still later with enzymes. The early research on fermentation dealt mostly with carbohydrates and reactions that liberated carbon dioxide. It was soon recognized, however, that microorganisms or enzymes acting on sugars did not always evolve gas. Further, many of the microorganisms and enzymes studied also had the ability to break down noncarbohydrate materials such as proteins and fats, which yielded carbon dioxide, other gases, and a wide range of additional materials. Currently, the term fermentation is used in various ways which require clarification. When chemical change is discussed at the molecular level, in the context of comparative physiology and biochemistry, the term fermentation is correctly employed to describe the breakdown of carbohydrate materials under anaerobic conditions. In a somewhat broader and less precise usage, where primary interest is in describing the end products rather than the mechanisms of biochemical reactions, the term fermentation refers to breakdown of carbohydrate and carbohydrate like materials under either anaerobic or aerobic conditions. Conversion of lactose to lactic acid by Streptococcus lactis bacteria is favoured by anaerobic conditions and is true fermentation; conversion of ethyl alcohol to acetic acid by Acetobacter aceti bacteria is favoured by aerobic conditions and is more correctly termed an oxidation rather than a fermentation. But the word fermentation also is used in a still broader and less precise manner. The term fermented foods is used to describe a special class of food products characterized by various kinds of carbohydrate breakdown; but seldom is carbohydrate the only constituent acted upon.

Most fermented foods contain a complex mixture of carbohydrates, proteins, fats, and so on, undergoing modification simultaneously, or in some sequence, under the action of variety of micro- organisms and enzymes. This creates the need for additional terms to distinguish between major types of change. Those reactions involving carbohydrates and carbohydrate like materials (true fermentations) are referred to as "fermentative". Changes in proteinaceous materials are designated proteolytic or putrefactive. Breakdowns of fatty substances are described as lipolytic. When complex foods are "fermented" under naturalconditions, they invariably undergo different degrees of each of these types of change. Whether fermentative, proteolytic, or lipolytic end products dominate will depend on the nature of the food, the types of microorganisms present, and environmental conditions affecting their growth and metabolic patterns. In specific food fermentations, control of the types of microorganisms and environmental conditions to produce desired product characteristics is necessary. Fermentations occur when microorganisms consume

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susceptible organic substrates as part of their own metabolic processes. Such interactions are fundamental to the decomposition of natural materials, and to the ultimate return of chemical elements to the soil and air without which life could not be sustained. Natural fermentations have played a vital role in human development and are probably the oldest form of food preservation.

Although the growth of microorganisms in many foods is undesirable and considered spoilage, some fermentations are highly desirable. Fruit and fruit juices left to the elements acquired an alcoholic flavour; milk on standing became mildly acidic and eventually became cheese; cabbage turned to sauerkraut. These changes tasted good and so early civilizations encouraged the conditions that permitted them to occur. Sometimes the desired results were obtained repeatedly, but this was not always so. It soon was also discovered that certain alcoholic fruit juices and sour milks would keep well, and so part of the food supply was converted into these terms as a means of preservation.

Today, other methods of food preservation are superior to fermentation as means of preserving many foods. In technically advanced societies the major importance of fermented foods has come to be the variety they add to diets. In many less developed areas of the world, however, fermentation and natural drying are still the major food preservation methods, and, as such, are vital to survival of much of the world's population, The various preservation methods are based on the applications of heat, cold, radiation, removal of water, and other principles, all have the common objective of decreasing the numbers of living organisms in foods, or at least holding them in check against further multiplication. In contrast, fermentation, whether for preservation purposes or not, encourages the multiplication of microorganisms and their metabolic activities in foods. But only selected organisms are encouraged, and their metabolic activities and end products are highly desirable. The increasing application of biotechnology and genetic engineering techniques to food production is bringing added importance to food fermentations.

Acetic, lactic and alcoholic are the three important kinds of fermentation involved in fruit and vegetable preservation. The keeping quality of vinegar, fermented pickles and alcoholic beverages depends upon the presence of acetic acid, lactic acid and alcohol, respectively. Care should be taken to exclude air from the fermented products to avoid further unwanted or secondary fermentation. Wines, cider, vinegar, fermented pickles and other fermented beverage, etc., are prepared by these processes.

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Vinegar

Vinegar is perhaps the oldest known product or fermentation. The word is derived from French 'vinaigre' meaning sour wine (vin = wine, aigre= sour). Vinegar is a liquid obtained by alcoholic

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and acetic fermentation of suitable materials containing sugar and starch (at least 10 per cent fermentable sugar). It contains about 5 per cent acetic acid and has germicidal and antiseptic properties. In the trade, vinegar is labelled according to the material used in its manufacture, e.g., malt vinegar (from malt) and cider vinegar (from apple juice). The amount of acid in vinegar is expressed as 'grain strength' which is ten times the percentage of the acetic acid present in it, e.g., vinegar having 5 per cent acetic acid is termed as vinegar of '50 grain strength'.

Types of vinegar

Vinegars are of two types-

(A) Brewed vinegars, and (B) Artificial vinegars

(A) Brewed vinegars : Brewed vinegars are made from various fruits, starchy materials (potato) and sugar containing substances (molasses, honey) by alcoholic and subsequent acetic fermentation.

(1) Fruit vinegar: Generally apple, grape, orange, jamun, peach, pear, pineapple, apricot and banana are used. Vinegar made from apple juice is known as cider or apple cider vinegar, while that from grapes as wine or grape vinegar.

(2) Potato vinegar: In this case starch is extracted from potato and hydrolyzed by the enzyme diastase before fermentation.

(3) Malt vinegar: Malt vinegar is derived wholly from malted barley, with or without the addition of the cereal grain, malted or otherwise, the starch of which is saccharified by the diastase of the malt before fermentation. Distilled malt vinegar is prepared by distilling the malt vinegar. The product merely contains the volatile constituents of the vinegar from which it is derived. It is colourless and is generally used in the manufacture of pickled onions.

(4) Molasses vinegar: In this case molasses is diluted to 16 per cent total soluble solids, neutralized with citric acid and then fermented.

(5) Honey vinegar: It is prepared from low grade honey.

(6) Spirit vinegar: Spirit vinegar is the product prepared by acetous fermentation of a distilled alcoholic fluid which in turn is produced by fermentation. It is usually made by alcoholic fermentation of molasses and then distilled prior to acetic fermentation. It is also called as grain vinegar. distilled vinegar, white vinegar or alcohol vinegar.

(7) Spiced vinegar: Spiced vinegars are prepared by steeping the leaves or spices in an ordinary vinegar.

(8) Artificial vinegars: Artificial vinegars are prepared by diluting synthetic acetic acid or glacial acetic acid to a legal standard of 4 per cent and are coloured with caramel. Artificial vinegars are also called as synthetic vinegar or non-brewed vinegar.

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Steps involved in vinegar production

Two distinct steps are involved in its preparation.

(i) Conversion of the sugar in fruits, etc., into alcohol by yeast (alcoholic fermentation) : The most efficient yeasts for fermentation of sugary substances and fruit juices into alcohol are Saccharomyces ellipsoideus, S. malei and S. cerevisiae. For starchy substances. S. cerevisiae is the best. In order to obtain quality vinegar, it is essential to first destroy wild (naturally occurring) yeasts and other microorganisms by pasteurization, and then to inoculate pure yeast. The nutrients for the growth of yeast such as phosphates, ammonium and potassium salts and sugars are naturally present in fruit juices and in honey and molasses. The most favourable temperature for the growth of yeast is 25-27°C. Fermentation becomes abnormal at 38°C and ceases altogether at 41°C and below 7.0C. The chemical reaction involved in alcoholic fermentation is as under:

(ii) Conversion of alcohol into vinegar by acetic acid bacteria (acetification) Acetic acid fermentation is brought about by acetic acid bacteria (Acetobacter spp.) which are strongly aerobic but whose activity is greatly reduced by light. Acetic acid fermentation should, therefore, be carried out in the dark. The nutrients required for bacterial growth are generally present in the alcoholic liquor itself, but in the case or distilled alcohol, malt sprouts phosphoric acid, potassium carbonate, trisodium phosphate and ammonium hydroxide are added as nutrients. For acetic acid fermentation, the alcohol content of the fermented mash is adjusted to 7-8 per cent by dilution with water, because acetic acid bacteria do not grow well at higher concentration! of alcohol. After this adjustment, mother vinegar containing acetic acid bacteria is added at the rate of one part to ten parts of fermented mash in order to check the growth of undesirable microorganisms and to hasten the fermentation process. The chemical reaction involved is as under:

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Preparation of vinegar

Vinegar is prepared by the following methods:

(A) Slow process

(B) Orleans slow process

(C) Quick process (Generator or German process)

(A) Slow process

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This process is generally used in India. The fruit juice or sugar solution, filled in earthen pots or wooden barrels, is kept for at least 5-6 months in a warm, damp room to undergo spontaneous alcoholic and acetic fermentations. No special care is taken, but the mouth of the container is covered with cloth to keep out insects, dirt, etc. The main defects of this method are:

(i) Incomplete alcoholic fermentation;

(ii) Slow acetic fermentation;

(iii) Low yield; and

(iv) Inferior quality of vinegar.

(B) Orleans slow process

The vinegar prepared by this process is clear and of superior quality. The steps of the process are:

1. Selection of fruit: Grapes, apples, oranges, mangoes, dates, jamun, or any other sweet fruit of third grade having about 10 per cent sugar in the juice are taken. Cores and peels of certain fruits discarded during canning and jam making can also be used.

2 Extraction of juice : The fruits or vegetables are cut into small pieces and then crushed or pressed through a thick muslin cloth. Fruits which do not yield juice readily are heated with a small quantity of water before pressing.

3. Adjustment of sugar: Only juice containing low percentage of sugar is suitable for the growth of yeast. The concentration of sugar is determined by means of a hand refractometer and adjusted to about 10 per cent either by diluting the juice with water (if the sugar content is high) or by adding additional sugar.

4. Fermentation: The juice is heated (pasteurized) to destroy the microorganisms and then filled in glass carboys, earthen pots or wooden barrels (Fig.A) to threefourths of their capacity. The two important steps in the preparation of vinegar are:

a. Alcoholic fermentation

b. Vinegar fermentation.

a. Alcoholic fermentation: Pure wine yeast, obtained from a winery or a chemist's shop, is well powdered and dissolved in a little warm juice and then added at the rate of 1.5 g per litre to the whole lot of juice with frequent stirring. The mouth of the carboy or barrel is loosely plugged with cotton wool to allow carbon dioxide gas to escape. The gas should be completely removed otherwise it hinders the yeast fermentation. Initially there is continuous frothing which indicates the progress of fermentation, but it ceases after 3 weeks when the fermentation is complete. All the sugar is converted into alcohol as can be seen by testing with a hand refractometer which indicates 0-1 per cent total soluble solids.

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During the fermentation the temperature is maintained at 22 to 27°C as fermentation ceases above 41°C and below 7°C. The fermented juice is stored for 1 to 2 weeks for sedimentation and then strained through a cloth, or the clear supernatant is syphoned off into a clean container which is filled up to three-fourths its capacity :( Fig. B). Vinegar fermentation should be taken up only after ascertaining that the alcoholic fermentation is complete, otherwise yeast will retard the fermentation. For vinegar fermentation the alcohol content of the fermented liquid is adjusted to 7-8 per cent by dilution with water, because acetic acid bacteria do not grow at a higher concentration of alcohol.

b.Vinegar (acetic) fermentation: This is brought about by acetic acid bacteria. Unpasteurized vinegar or "mother" vinegar is added to the product of alcoholic fermentation in the ratio of 1: 10, and mixed well. Thereafter the liquid should not be disturbed otherwise the firm of vinegar bacteria will break and sink to the bottom and consume the nutrients in the liquid without producing vinegar. The mouth of the container is closed with a cork having two holes for proper aeration. The temperature of this liquid is maintained at 21 to 2rC and the fermentation is completed in 10 to 15 weeks when the acetic acid content reaches a maximum. Then the vinegar is syphoned off or strained through a thick cloth leaving at the bottom of the container a turbid liquid, which is used as "mother" vinegar for fresh fermentation.

5. Aging: Vinegar prepared by the above method is turbid and does not possess a good taste. It is stored in containers for 4 to 8 months during which the vinegar develops a good aroma and flavour and becomes mellow.

6. Clarification: The dear aged liquid should be syphoned out and filtered.

7. Colouring: Caramel colour is added for colouring.

8. Pasteurization: The vinegar is poured into previously sterilized bottles, corked airtight and the bottles heated (pasteurized) in hot water at 71 to 77°C for 15 to 20 minutes, so that further growth of bacteria is stopped and the strength of vinegar maintained during storage.

Note: An ideal vinegar should contain only about 0.3 per cent sugar. A higher percentage denotes incomplete fermentation due, to excess of acetic acid during yeast fermentation.

(C) Quick process (Generator or German process)

In this process additional oxygen is supplied for the growth of bacteria and the surface of the bacterial culture is also increased resulting in rapid fermentation. The equipment, used known as "Upright Generator", is a cylinder of height 3.66 to 4.2 m and diameter 1.2 to 1.5 m which is divided into three compartments:

(i) Distributing (ii) Central, and (iii) Receiving.

(i) Distributing compartment: This is the upper compartment and is about 30 cm above the central one. It is separated from the central compartment by a partition having small perforations. In the distributing compartment then! is fitted a W-shaped tilting trough or revolving sprinkler which distributes the liquid by trickling slowly over the material filled in the central compartment.

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(il) Central compartment: This is filled with pumice stone, straw, corn cobs, rattan or beech wood shavings to increase the surface area. Beech wood shavings are preferred as they remain tightly coiled even when wet with vinegar. This compartment is fitted with an adjustable opening near the bottom for admission of air.

(iii) Receiving compartment: This is the lowest compartment of the generator and is separated from the central one by a perforated partition placed about 1.5 m above the bottom of the generator. Here the vinegar is collected.

Method of Preparation: The material in the central compartment is sprinkled and wetted with unpasteurized vinegar containing acetic bacteria. Then a mixture of the alcoholic fermentation product and vinegar (2: 1) is slowly trickled through the generator to promote the growth of vinegar bacteria. Within a few days the bacterial growth is enough for efficient functioning of the generator. The alcoholic fermentation liquid is now mixed with mother vinegar in the ratio of 1: 2 to increase its acidity from 3 to 3.5 per cent and passed through the generator.

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Tomato products: preparation of tomato puree, tomato ketchup, tomato juice, canning of tomatoes, grading of canned tomatoes.

Introduction

Tomato (Lycopersicon esculentum L) is both qualitatively and quantitatively a worldwide important vegetable, with an annual estimated production of 88 million tones (Eipeson 2003). The word “tomato” is derived from the Mexican Nahuati Indian word “tomati.” It originated in the Andes of South America and evolved from the cherry tomato (L. esculentum var. cerasiforme) (Jy et al. 2004). Tomato, a warm-season crop, belongs to fruit vegetables, and the Solanaceae family. It requires day temperatures of 25–30◦C and night temperatures of 16–20◦C for optimal growth (Rubatzky and Yamaguchi 1997; Decoteau 2000). The fruit set is best between 18 and 24◦C, the night temperatures being more critical than day temperatures. The tomato fruit is classified botanically as a berry, the size varying from small cherry types, with only two divisions of the ovary (locules), processing tomatoes, to commercial cultivar for fresh market with 4–6 locules (Benton-Jones 2008.

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Tomato Biochemistry and Nutrition

Composition and Nutritional Quality

The yield and quality of tomato products depend in great measure upon the composition of the raw material. The proximate composition, minerals, and vitamins content of raw tomatoes and commercially processed tomato products are shown in Table 37.2 (USDA 2009). The percentage of solids in tomatoes varies due to variety, character of soil, and specially, the amount of rainfall during the growing and harvesting season (Gould 1983). About half of the soluble solids are composed of reducing sugars, glucose and fructose. Acids contribute about one-eighth of soluble solids, considered to be almost entirely citric while traces of malic, tartaric, succinic, acetic, and oxalic acids have also been reported. Higher solids content of tomato usually causes stronger flavor. Polysaccharides, pectins, arabinogalactans, xylans, and arabinoxylans, are present to a varying concentration (Leoni 2002).

Tomato firmnes is dependent on an increase in total pectin, presence of some minerals (Ca and Mg), or decrease in degree of pectin esterification (Belitz et al. 2009). Tomatoes are a rich source of lycopene, an antioxidant. The concentration of lycopene varies with the stage of maturity, with the highest concentration in fully ripe red tomatoes (Figure 37.1, USDA 2009).

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Dietary intakes of tomatoes and tomato products containing lycopene have been related epidemiologically to lower incidence of cardiovascular disease and of prostate, gastrointestinal, and epithelial cell cancer (Ishida and Chapman 2004; Rao and Rao 2007). Its organic acids contribute to acid–base balance for consumer acceptability (Adedeji et al. 2006). In addition to lycopene, tomato is a good reservoir of diverse antioxidant molecules, such as ascorbic acid, vitamin E, carotenoids, and flavonoids. The nutritional composition of tomatoes varies with the color of a particular variety. Figure 37.2 shows vitamin C content in green, yellow, orange, and red tomatoes (USDA 2009).

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Processed Tomato Products

Tomato is a versatile vegetable from which a variety of processed products are produced. The most common processed products are juice, sauce, paste, ketchup/catsup, soup, and canned tomatoes. Figure 37.5 shows an overview of the processing of various tomato products; a detailed discussion about these processed products follows.

Tomato Pulp (Puree) and Paste

The definition of tomato pulp (puree) under the Food and Drug Administration (FDA) is the food prepared from one or any combination of the following ingredients: (1) the liquid obtained from mature tomatoes of red or reddish varieties; (2) the liquid obtained from the residue from preparing such tomatoes for canning; (3) the liquid obtained from the residue from partial extraction of juice from such tomatoes; and (4) salt. In the case of tomato paste, the preliminary options (1–4) are the same; additionally, it may contain (5) spices, (6) flavoring, and (7) baking soda. Tomato puree or paste is finel dispersed slurry from which skins and seeds have been removed by passing the mashed tomatoes through a pulper or finisher. Tomato paste differs from tomato puree only in the degree to which the concentration is carried. Product must contain at least 24% of natural tomato soluble solids (NTSS) for tomato paste and at least 8% salt-free tomato solids for tomato pulp (Gould 1983). At the end of trimming belt, tomatoes go through a break system to be chopped. Crushed (chopped) tomatoes can be processed into juice by either a hot-break or a cold-break method. The unit operation in pulp, paste, and juice processing are as follows:

Break (hot and cold): The selection of type of operation depends on the quality of raw tomatoes. Some break systems operate under vacuum to minimize oxidation. In an industrial process under vacuum, degradation of ascorbic acid is minimal during the break process. In absence of vacuum, greater loss of ascorbic acid takes places due to higher break temperatures (Trifir et al. 1998). In the hot-break method, red-ripe tomatoes are chopped and heated rapidly to at least 180◦F (82.2◦C) before pulping. The preliminary heat given to the tomatoes inhibits pectolytic enzymes and protects the constituents of the tomato (especially pectin) from enzymatic changes, which results in maximum viscosity of finishe product. Thus, to get higher viscosity, juices are commonly produced under hot-break at 200–210◦F or 93–99◦C (Barringer 2003b). In coldbreak systems, tomatoes (greenand immature type) are chopped at 140–151◦F (60–66◦C). The chopped tomatoes fall into a holding tank, where they are held for varying times so as to facilitate the breakdown of pectin catalyzed by the enzymes released by crushing process (Gould 1983). Cold-break juice has a lower destruction of color and flavor.

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Extraction and refining (filtration) of juice:

The preheated tomato pulp is run through a series of extractors or cyclones to remove the seeds, skins, and any other pulp and impurities. Juice extraction may be accomplished by the screw- or the paddle-type extractors (Trifir et al. 1998). The screw-type extractors press the tomatoes between the screw and the screen. The screw-paddletype extractors beat the tomato against the screen. The beating action of a paddle pulper and a paddle finishe gives a relatively higher juice yield than the screwtype juice extractor (Gould 1983). Air incorporation during extraction should be minimized since it oxidizes both lycopene and ascorbic acid. The screen size determines the finish or particle size, which will affect the viscosity and texture (Barringer 2004a).

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Concentration (evaporation): The concentration process results in progressive increase in solids content of pulp to get a paste with desired concentration, and viscosity (normally about 24–38% solids). The method by which the juice is concentrated varies from tanks with coils in batch-type vacuum evaporators to continuous vacuum evaporators with a series of effects. The temperature is raised as the juice goes to each successive effect; Barringer (2004a) described the typical temperature range of 118–180◦F (47.8–82◦C) for this process.

In order to adjust total soluble solid in tomato juice and improve flavor, 1.5–1.7% NaCl is added to the juice. The use of non cellulosic membranes, having high retention of low molecular weight organics, and good physical and chemical stability, enabled reverse osmosis to be used on a commercial scale for the concentration of tomato juice (Pepper et al. 1985).

Sterilization and packaging: The tomato paste is packed either conventionally or aseptically (Figure 37.4c). Canned tomato paste is usually hot-fille at a minimum temperature of 194◦F (90◦C) into cans. It is then sealed without further heat treatment and passed through a water spray to remove any residue on the outside, cooled, and packed. Aseptic packaging of tomato paste usually involves heat treatment at 105–110◦C for 2.25 minutes or 96◦C for 3 minutes, cooling to 35–38◦C, and fill in aseptically into high-barrier aseptic bags. Aseptically processed products must be cooled before fill in to maintain high quality. An aseptic bag-in-drum or bagin- crate fille may be used for this purpose. Bulk paste is typically sold in 55-gallon drums or 300 gallon bag-in-boxes (Barringer 2004a).

Canned Whole Tomatoes

Peeling, sorting, and filling Tomatoes must be peeled before processing into canned products—whole or stewed. The main defects of concern are those included in the USDA grading standards for canned products: presence of peel, extraneous vegetable material, blemished areas, discolored portions, and objectionable core material (Downing 1996). Inadequately peeled, blemished, small, and misshapen fruit are diverted to the juice line. Filling the cans with tomatoes is an important unit operation. Fancy whole, evenly colored, large tomatoes are packed by hand, but due to labor costs, almost all manufacturers use mechanical filling In this case, peeled tomatoes are placed into a hopper and a mixture of whole tomatoes and juice fill the enameled cans automatically. The California standard-pack canned tomatoes consist of a mixture of peeled tomatoes and tomato puree (Gould 1983).

Additive: Firmness is a major factor in determining the quality of canned whole tomatoes. The addition of calcium salt, mainly in the form of CaCl2, cause the formation of a calcium pectate gel or pectinate, which improves product firm ness (Gould 1983). The final amount of calcium cannot exceed 0.045% by weight in whole tomatoes or 0.08% in dices, slices, and wedges. The standard of identity allows using calcium, any edible organic acids (to lower the pH as needed), sweeteners (to offset the tartness from the added acid), salt (for taste), spices, flavoring, and vegetables (US-CFR 2000).

Exhausting and sealing: Exhausting, which helps create vacuum upon sealing, prevents seal damage during heat treatment. The center of the can should reach at least 130◦F (54.4◦C) and the length of the exhaust should be adjusted to accomplish this temperature. Too short an exhaust may cause “springers” or “flippers” through overfilling(Gould 1983).

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Four methods are available for exhausting: mechanical vacuum, thermal exhausting, hot filling and steam fl w closing. Cans are typically exhausted and sealed at the same time. Without adequate headspace the ends of the can will bulge out. This is referred to as a “flipper” if the end can be pushed back down, or a “hard swell” if it cannot (Barringer 2003a). An airtight (hermetic) seal for cans is achieved by a double-roll seaming process.

Thermal processing: Tomato products can be hot fille and held, or processed in a retort as needed to minimize spoilage. The agitating continuous retort for tomatoes operate at 212◦F (100◦C) and is the most commonly used for tomato products. Continuous rotary retorts set at 220◦F (104◦C) for 30–40 minutes. High temperature and short time in flame are also common. The process time and temperature of canned tomato depends on the type of equipment, and the can size (Barringer 2003a). However, it is essential to check the temperature of the processed cans in its cold point to ascertain the efficiency of the process.

Cooling, labeling, and packing: Cans are cooled completely and quickly to a temperature below 100◦F or 37.8◦C after thermal processing. This avoids “stack burning,” which results in lower drained weight, browning of the color, and loss of flavor. When cooling water is used, it should be chlorinated to 15 ppm free chlorine to maintain a zero or low bacterial count (Downing 1996). The containers are then labeled and stored.

Other Canned Products

Diced tomatoes, sliced tomatoes, and tomato wedges are some other canned products. Diced tomatoes have become very popular because of the increase in salsa consumption, and are processed in a similar manner to canned tomatoes. Calcium treatment, either by bath or immersion, is necessary to maintain firmness/texture. Calcification can occur by conveying the dices through a calcium bath. Immersion causes a significant loss of acid and sugar compared to addition of calcium to the can. However, immersion results in significant firmed tomatoes for the same final calcium content (Villari et al. 1997). In general, calcium concentration in the dipping solution is the most important factor.

Tomato Juice

Tomato juice is define as the unconcentrated liquid extracted from mature tomatoes of red or reddish varieties, with or without scalding followed by straining. Such liquid is strained free from skins, seeds, and other hard substances but carries finely divided insoluble solids from the flesh of the tomato. In manufacturing tomato juice, the tomatoes are subjected to the same unit operations as previously described in the preparation of tomatoes for paste or canning.

Crushing, breaking, and extraction: Crushing and hot break may be applied without any water added. In this case, heat treatment in a rotary coil tank followed by a heat exchanger and holding tube would be suitable for inactivation of the pectic enzymes fast enough to retain 90% of the potential serum viscosity in the original fresh tomato (Tressler and Joslyn 1971). Cold-break tomato extract pass directly to the inspection belt to chopper and then extractor. Quick processing/ extraction of juice is necessary to produce high-quality tomato juice by cold-break procedure.

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Deaeration, salting, and filling Air removal is important from nutritional point of view, especially in preventing ascorbic acid reduction during heat treatment. This could be avoided by using a vacuum deaerator immediately after extraction of the juice. Normally a 100◦C flas is sufficien to remove the dissolved and occluded air. Deaeration also prevents foaming during concentration. Salt may be added by dropping tablets to each can, or injecting concentrated brine into tomato juice or serum (Tressler and Joslyn 1971). The sodium chloride added to tomato juice ranges from 0.5 to 1.25% by weight with an average content of 0.65% for commercial samples (Gould 1983).

Homogenization and thermal processing: Tomato juice is sometimes homogenized before canning in a homogenizer. Homogenization, generally used for cold break juice, prevents settling of the solids and produces a thicker-bodied juice and minimizes solids separation. Tomato juice may also be milled to assist in control of separation and product consistency (Gould 1983). Commercially, canned tomato juice should be heated either before or after filling to prevent spoilage. The following methods are currently employed: (1) In-can processing which may be accomplished by (a) pressure processing in continuous retort, (b) atmospheric processing in continuous agitating retort, (c) Boiling water process, or (d) hot fil followed by steam processing at atmospheric pressure; and (2) Bulk processing method by either (a) flash sterilization followed by hot fill-hold- ater cool, or (b) hot fill hold-air cool. The quality evaluation of tomato juice as affected by processing methods especially high intensity pulsed electric field (HIPEF) has been researched extensively. According to Odriozola-Serrano et al. (2009), HIPEF-processed tomato juices maintained higher content of carotenoids (lycopene, neurosporene, and gamma-carotene), quercetin, higher values of lightness and viscosity (Aguilo-Aguayo et al. 2008), and higher lycopene and vitamin C content (Odriozola- Serrano et al. 2008b) during storage than thermally and untreated juices. The HIPEF technology has a potential to be an alternative to thermal treatment to obtain tomato juice with a high presence of health-related compounds. Moreover, HIPEF and pressure processing induced a specifi range of reduction in peroxidase and polygalacturonase (Aguilo- Aguayo et al. 2008; Hsu 2008).

Tomato Catsup

It is made from strained tomato juice or pulp and spices, salt, sugar and vinegar, with or without onion and garlic, and contains not less than 12 percent tomato solids and 25 per cent total solids. According to FDA, catsup, ketchup, or catchup is the food prepared from one or any combination of the following ingredients:

(1) the liquid obtained from mature tomatoes of red or reddish varieties, (2) the liquid obtained from the residue from preparing such tomato for canning consisting of peeling and cores with or without such tomatoes or pieces thereof, and (3) the liquid obtained from the residue from partial extraction of juice from such tomatoes. Tomato ketchup may be made directly from fresh or concentrated pulp. The use of tomato pulp powder can be used as a thickening agent in the formulation of tomato ketchup (Farahnaky et al. 2008). Manufacturing steps for producing tomato catsup are described below (Gould 1983).

Crushing, breaking, and pulping: Following washing, sorting, and trimming, the tomatoes are normally chopped, and heated as described for hot-break juice and paste, then put through pulper.Tomatoes may be treated by foodgradeacid or alkali solution to obtain a pH of 4.2 ± 0.2,

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prior to straining. The liquid product is then pumped to the concentration tanks or continuous evaporators.

Formulation: In addition to tomato paste, the constituents used in the manufacture of catsup include water, sugar, salt, vinegar, spices, flavorings, onions, garlic, and stabilizers. It is to be noted that the definition of tomato catsup does not permit the use of artificial color, artificial preservatives, or added thickeners of any kind. Sweetener is added gradually and preferably during the latter part of cooking. Catsup diversity mostly comes from its spices and fl vorings. Spices (high grade or extract) may be used either in the form of whole or ground spices which should be used at the beginning of the cook or in the form of volatile spice oils before finishin the catsup. The addition of garlic and onions can be made with the spices or in a separate bag, after cooking for 20–30 minutes.

Cooking, finishing, and homogenization: A high steam pressure, 90–120 psi, is the best way to prevent burning and sticking on kettles or coils. It ensures circulation in the batch and so there will be no need for installing propeller. The evaporation of a batch should not take more than 45 minutes. It should not be less than 30 minutes if whole spices are used. A long slow cook gives a flat soggy body, whereas one of less than 30 minutes may fail to extract the spices. Catsup goes through the finishe to give a smooth body right after concentration. For controlling the consistency of bottled catsup, mechanical cell fragmentations by homogenizer and milling processes are currently used after finishers Further, the higher pressure and temperature in milling result in the higher consistency of tomato catsup due to extracted pectin.

Deaeration, fillin , sterilizing, and cooling: From the milling process, the catsup is placed in a holding tank supplying the filling machine. Air removal is essential before filling The presence of air may result in excessive headspace or endanger the desirable bright color of the product, i.e., a relatively frequent defect called “black neck.” Each charge, which is usually made batch wise, is fed via a plate-type heat exchanger (90◦C) and a degassing device to a hot-filling apparatus with subsequent cooling. Further heating is unnecessary because it may impair the color of the product.

Chili Sauce

This product is of the same general character as catsup, but is made from peeled and cored large to medium-sized tomatoes without removing seeds. It contains added sugar and onions and, is sometimes made hotter in flavor than catsup. The cooking and handling are the same whereas the finishing operation is eliminated for chili sauce. Some sauces aremade directly from fresh tomatoes during the tomato season, but this is less common. Sauce production from paste by mixing it with water, particulates, and spices is more common. The sauce may be aseptically packaged, or immediately filled into the final container. Depending on ingredients used, the product may not undergo any further heat processing (Barringer 2004b).

Tomato chutney: Tomato 1 kg, sugar 500 g, salt 25 g, onion (chopped)100 g, ginger (chopped) 10 g, garlic (chopped) 5 g, red chilli powder 10 g, cinnamon, black pepper, cardamom (large), aniseed, cumin (powdered) 10 g each, vinegar 100 ml and sodium benzoate 0.5 g per kg final product.

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Tomato cocktail: It is prepared just before serving or served from stock.

Recipe: Tomato juice 5litres, salt 45 g, lime juice 60 ml, red chilli powder 0.25 g, clove (headless) 5 numbers, cumin, black pepper, coriander seed, cardamom (large), cinnamon (powdered) 1.5 g each and vinegar (10% acetic acid) 300 ml.

Tomato soup: Soup is becoming very popular in homes. Stored soup is warmed at the time of serving.

Recipe: Tomato pulp 1 kg, salt 20 g, sugar 20 g, butter or cream 20 g, flour/starch 10 g, onion (chopped) 20 g, garlic (chopped) 5 g, clove (headless) 5 numbers, cumin, cardamom (large), black pepper, cinnamon (powdered) 1 g each and water 350 ml.

By-Products from Tomato Processing Waste

In the case of tomato, the solid waste or pomace, remaining after the juice/pulp extraction process, consists of skin, seeds, fibrous matter, trimmings, cores, and cull tomato, which can be used for producing value-added products. Tomato pomace leftover, as a waste after extraction of tomato juice, constitutes about 20–30% of the raw material and may be used as a substrate for the production of vitamin B12 (Haddadin et al. 2001). The pomace essentially consists of seeds and skin. The seed component of the waste, which accounts for about 55% of the total mass, has received considerable scientific investigation. Bread supplemented with tomato seed had improved loaf volume, texture, and crumb quality, because of anti staling properties (Sogi et al. 2005).Because of the growing demand for natural lycopene, considerable interest has been directed toward obtaining lycopene from tomato pulp, tomato paste, and tomato processing wastes. However, the available solvent extraction technologies do not seem to allow a fast and economic recovery of its carotenoids. For example, only about 50% of total lycopene was extracted from tomato processing waste using supercritical CO2 at 60◦C and 30 MPa (Sabio et al. 2003). The results indicate that a mild enzymatic treatment can lead to significant more lycopene recovery (70–98%) from tomato peels (Sogi et al. 2005). However, using a new high pressure process, it is possible to recover all trans lycopene (_98% purity) from industrial tomato by-products (Naviglio et al. 2008b). Lycopene is transferred, due to the high pressure used, in the form of molecular aggregates into water as dispersion, while a polar compounds remain in the matrix. The aggregates are easily purifie in a single subsequent step using methanol, thus obtaining lycopene at 98% chromatographic purity or higher (Naviglio et al. 2008a).

Part-B (Chocolate and confectionery)

1. Major candy types with crystalline and non- crystalline sugar such as rock candy, fondant cream, gum drops, toffees etc.

2. Ingredients for making confectionery, chocolate and related materials. Confectionery manufacturing practices, chemical and allied substances used in confectionery. Use of lecithin in chocolate. Microbiological and other spoilage problems.

Introduction

The confectionery industry divides confectionery into three classes: chocolate confectionery, flour confectionery and sugar confectionery. Chocolate confectionery is obviously things made

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out of chocolate. Flour confectionery covers items made out of flour. Traditionally, and confusingly, this covers both long life products, such as biscuits, in addition to short-life bakery products. Sugar confectionery covers the rest of confectionery. In spite of the above definition, liquorice, which does contain flour, is considered to be sugar confectionery. The confectionery industry has created many confectionery products that are a mixture of categories, e.g. a flour or sugar confectionery centre that is covered with chocolate. There is another category that is sometimes referred to as 'sugar-free sugar confectionery'. This oxymoron refers to products that resemble sugar confectionery products but which are made without any sugars. The usual reason for making these products is to satisfy special dietary needs. A better name might be 'sugar confectionery analogues'. The manufacture of confectionery is not a science-based industry. Confectionery products have traditionally been created by skilled craftsman confectioners working empirically, and scientific understanding of confectionery products has been acquired retroactively. Historically, sugar confectionery does have a link with one of the science-based industries - pharmaceuticals. In the eighteenth century, sugar confectionery products were made by pharmacists as pleasant products because the active pharmaceutical products were unpleasant. The two industries continue to share some technology, such as making sugar tablets and applying panned sugar coatings. There are products that although apparently confectionery are legally medicines. This usually applies to cough sweets and similar products. In the United Kingdom these products are regulated under the Medicines Act and require a product licence. This means that all the ingredients for the product are specified and cannot easily be altered. The dividing line between confectionery and medicines is not uniform in all countries.

Sugar confectionery

Sugar confectionery refers to a large range of food items, commonly known as sweets. Boiled sweets, toffees, marshmallows, and fondant are all examples. Sweets are a non-essential commodity, but are consumed by people from most income groups. The variety of products is enormous, ranging from cheap, individually-wrapped sweets, to those presented in boxes with sophisticated packaging.

Nutritional significance

The main ingredient used in the production of sweets is sugar (sucrose). There is a danger that if sweets are consumed in excess over a prolonged period of time they may contribute to obesity. Unless good dental care is practiced, over-consumption can also lead to tooth decay.

Principles of sugar confectionery production

By varying the ingredients used, the temperature of boiling, and the method of shaping, it is possible to make a wide variety of products. In all cases, however, the principle of production remains the same and is outlined below:

· balance the recipe · prepare the ingredients · mix together the ingredients · boil the mixture until the desired temperature has been reached · cool

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· shape · pack.

Many factors affect the production and storage of sweets:

· the degree of sucrose inversion (see below) · the time and temperature of boiling · the residual moisture content in the confectionery · the addition of other ingredients.

Degree of inversion

Sweets containing high concentrations of sugar (sucrose) may crystallize either during manufacture or on storage (commonly referred to as graining). Although this may be desirable for certain products (such as fondant and fudge), in most other cases it is seen as a quality defect.

When a sugar solution is heated, a certain percentage of sucrose breaks down to form 'invert sugar'. This invert sugar inhibits sucrose crystallization and increases the overall concentration of sugars in the mixture. This natural process of inversion, however, makes it difficult to accurately assess the degree of invert sugar that will be produced.

As a way of controlling the amount of inversion, certain ingredients, such as cream of tartar or citric acid, may be used. Such ingredients accelerate the breakdown of sucrose into invert sugar, and thereby increase the overall percentage of invert sugar in the solution. A more accurate method of ensuring the correct balance of invert sugar is to add glucose syrup, as this will directly increase the proportion of invert sugar in the mixture. The amount of invert sugar in the sweet must be controlled, as too much may make the sweet prone to take up water from the air and become sticky. Too little will be insufficient to prevent crystallization of the sucrose. About 10-15 per cent of invert sugar is the amount required to give a non-crystalline product.

Time and temperature of boiling

The temperature of boiling is very important, as it directly affects the final sugar concentration and moisture content of the sweet. For a fixed concentration of sugar, a mixture will boil at the same temperature at the same altitude above sea-level, and therefore each type of sweet has a different heating temperature (see chart below).

Boiling point of sucrose solutions

Sucrose concentration (per cent) Degrees C Boiling point * Degrees F Boiling point *

40 101.4 214.5

50 102 215.5

60 103 217.5

70 105.5 222

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75 108 227

80 111 232

85 116 241

90 122 252

95 130 266

*at sea level.

Variations in boiling temperature can make a difference between a sticky, cloudy sweet or a dry, clear sweet. An accurate way of measuring the temperature is to use a sugar thermometer. Other tests can be used to assess the temperature (for example, toffee temperatures can be estimated by removing a sample, cooling it in water, and examining it when cold). The temperatures are known by distinctive names such as 'soft ball', 'hard ball' etc., all of which refer to the consistency of the cold toffee.

Type of sweet Temperature range for boiling (Degrees C)

Fondants 116-121

Fudge 116

Caramels and regular toffee 118-132

Hard toffee (e.g. butterscotch) 146-154

Hard-boiled sweets 149-166

Moisture content

The water left in the sweet will influence its storage behaviour and determine whether the product will dry out, or pick up, moisture. For sweets which contain more than 4 per cent moisture, it is likely that sucrose will crystallize on storage. The surface of the sweet will absorb water, the sucrose solution will subsequently weaken, and crystallization will occur at the surface - later spreading throughout the sweet.

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Added ingredients

The addition of certain ingredients can affect the temperature of boiling. For example, if liquid milk is used in the production of toffees, the moisture content of the mixture immediately increases, and will therefore require a longer boiling time in order to reach the desired moisture content.

Added ingredients also have an effect on the shelf-life of the sweet. Toffees, caramels, and fudges, which contain milk-solids and fat, have a higher viscosity, which controls crystallization. On the other hand, the use of fats may make the sweet prone to rancidity, and consequently the shelf-life will be shortened.

Types of sweets

Fondants and creams

Fondant is made by boiling a sugar solution with the optional addition of glucose syrup. The mixture is boiled to a temperature in the range of 116-121°C, cooled, and then beaten in order to control the crystallization process and reduce the size of the crystals. Creams are fondants which have been diluted with a weak sugar solution or water. These products are not very stable due to their high water content, and therefore have a shorter shelf-life than many other sugar confectionery products. Both fondants and creams are commonly used as soft centres for chocolates and other sweets. Fondants and creams are sugar confectionery products which contain mixed sugars held in two phases. The sugar crystals which constitute the solid phase, are dispersed in a high sugar solids syrup. Fondants and creams are similar in composition though creams contain slightly higher residual water and a greater proportion of doctor solids.

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Gelatin sweets

These sweets include gums, jellies, pastilles, and marshmallows. They are distinct from other sweets as they have a rather spongy texture which is set by gelatin. Gums, jellies and pastilles constitute a large class of confectionery products which can be manufactured with many interesting variations. They are comparatively low boiled and contain about 20% moisture. The texture of these products, which can be firm or solid, is obtained by the use of various types of water binding gelling agents principally gum arabic, starch, gelatine, agar and pectin. After a boiled mixture of mixed sugars has been prepared it is mixed with the gelling agent and then processed into the range of shapes by depositing into starch moulds. Other methods may be used principally depositing into rubber moulds or pouring onto a slab. After forming into shapes, the confections are dried to their final moisture content and texture by stoving.

Hard gums are normally prepared from gum arabic alone which is the major ingredient constituting some 50% of all total solid matter that is present. The texture produced is hard and short, but malleable. If the level of gum arabic is reduced to produce a softer eating product then another gelling agent such as gelatine will be required. These products are usually called pastilles. Gelatine jellies have a soft texture which is inclined to be rather rubbery. It is normal to use an additional gelling agent, such as thin boiling starch, to improve the texture and to give a shorter bite. The traditional 'wine gum' confections contain a large percentage of lower bloom gelatine, and it is this ingredient which produces the characteristic texture. Starch gums and jellies are becoming increasingly popular in Europe, compared to the United States of America where they have been manufactured in large amounts for many years. The gelling agent

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employed is thin boiling starch although many types of modified starches are now available and a wide variety of texture can be obtained. The texture of a traditional thin boiling starch based jelly is short and tender with a reasonable degree of resilience. Starches can be combined with any of the mentioned gelling agents.

Agar jellies are low boiled and soft, with a very short eating texture. It is usual to mix either jam or pastes such as minced figs together with the jelly to develop an acceptable texture. Pectin jellies also have a short soft texture, but provide an excellent base for fruit-flavoured products; normally the pH will be on the acid side, to enable the necessary gelling to take place. New types of pectin, such as the low methoxyl grades can be used in the manufacture of Turkish Delight. This type of pectin gives stable gels over a wide range of pH and blends well with thin boiling starch.

7. Pump to cooker.

8. Check total solids content after cooking; this should not vary by more than 2% water.

Toffee and caramels

Caramels and toffees are produced by blending glucose syrup, refined and / or brown sugar, milk solids (usually in the form of full cream condensed milk), fats and salt. The mix is then concentrated to a high total solids content. Differences between caramels and toffees lie normally in the amount of residual moisture left in the confection and in the amount of fat incorporated. Both products can be prepared by the traditional batch procedure or in the newer continuous production equipment.

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Batch Production Method

1. Load the open boiling pan with the glucose syrup, full cream condensed milk, refined or brown sugar.

2. Turn on the stirrers and then the heating and warm the mix to 35° C (95° F).

3. Add the hardened palm kernel oil and butter.

4. Mix for 10 minutes.

5. Turn on the heating and bring the batch to the boil.

6. Boil until the temperature reaches 124° C (255° F).

7. Release the heat from the pan.

8. Add the flavouring and mix for a short period. (The temperature of the batch should not rise to over 125° C (257 ° F) at this stage.)

9. Tum out the batch on to oiled slabs.

Fudge

Fudge is a cross between a caramel and a fondant. It is a grained medium boiled confection which contains both milk solids and a high fat content. The confection can be prepared by seeding with fondant or by mechanically inducing a grain in the cooked batch.

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Hard-boiled sweets

These are made from a concentrated solution of sugar which has been heated and then cooled to form a solid mass containing less than 2 per cent moisture. Within this group of products there is a wide scope to create many different colours, flavours and shapes through the use of added flavourings and colourings.

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Rock candy (also called rock sugar) is a type of confectionery mineral composed of relatively large sugar crystals. This candy is formed by allowing a supersaturated solution of sugar and water to crystallize onto a surface suitable for crystal nucleation, such as a string, stick, or plain granulated sugar. Heating the water before adding the sugar allows more sugar to dissolve thus producing larger crystals. Crystals form after 6–7 days. Food coloring may be added to the mixture to produce colored candy.

Chocolate confectionery

Chocolate is one of the most popular flavors in the world. It is widely used in many food products, including soups, main dishes, beverages, baked goods, and of course confectionery. Its basic ingredients are chocolate liquor, sugar, cocoa butter, and flavors. Other ingredients such as herbs, spices, milk, nuts, crisp rice, and so on, may also be added. Under conditions of semishade, warmth, and high humidity, cacao trees (Theobroma cacao) have thrived and been cultivated in the Americas for at least an estimated 4000 years. It was important in Mayan and Aztec mythology and also used as currency.

Originally, an unsweetened foamy beverage called chocolate was served to the noble ruling class. Early Spanish explorers found that adding sugar to this bitter chocolate liquid improved its flavor and soon became the rage of the Spanish nobilty. This sweetened chocolate liquid then spread to Italy, Holland, France, and England.

However, this sweetened chocolatl beverage was very rich in fat and difficult to disperse in water. Some consumers also had difficulty in digesting it. In the early 1800s, C.J. Van Houten of Holland patented a cocoa press that could separate chocolate liquor into cocoa butter and its residue, which is processed into cocoa powder. Mr. Van Houten was also credited with inventing the Dutch Process, by alkalizing the cocoa to give it a darker color and a less acid flavor. It was found that a superior product could be made with cocoa powder when warm water replaced the cocoa butter. Fry and Son in 1847 and Cadbury in 1849 were among the first to sell solid eating

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chocolate with a basic formula of chocolate liquor, sugar, and cocoa butter. The development of solid chocolate was made possible when the separation of cocoa butter from chocolate liquor resulted in an “excess” of cocoa butter. The addition of cocoa butter to chocolate liquor and sugar resulted in a smooth and creamy product. In 1875 Daniel Peter developed a method of adding condensed milk to chocolate and thus milk chocolate was born.

COCOA BEAN PRODUCTION

There are three major types of cocoa (cacao) beans: Forastero, Criollo, and Trinitario. The region where the cocoa beans are grown and its variety can greatly affect its characteristics for flavor, color, hardness of butter, and so on. Forastero beans are generally dark brown in color with a strong, bitter flavor and account for the majority of the beans. Criollo beans are the flavor beans. They are lighter in color with a mild, nutty flavor. Trinitario is basically a cross between Criollo and Forastero. The beans are blended to produce the desired end product.

Cacao trees are commercially cultivated generally within a 208 latitude of the equator with a rainfall of 45–100 in. (114–254 cm) and a temperature of 70–908F (21–328C). Africa (Ghana, Nigeria, Ivory Coast), South America (Brazil, Ecuador, Venezuela), the West Indies (Dominican Republic), Asia and Oceania (New Guinea, Malaysia, Indonesia) are the major producing areas.

A cacao tree will attain its full height in about 10 years. Although trees may grow to 40 ft (1200 cm) in height, they are usually pruned to 15–25 ft (450–750 cm) to facilitate harvesting. Flower clusters appear only on the trunk and main branches, with 20 to 30 fruit pods developing about five to six months later. The growth cycle is continuous, so a tree may bear leaves, blossoms, and pods simultaneously. However, the main fruiting season occurs between October and February. The ripe pods are elliptical in form, 7–10 in. (18–25 cm) in length and 3–5 in. (8–13 cm) in diameter, containing approximately 20–50 seeds surrounded by a mucilaginous pulp. Each dried cacao bean weighs approximately 1 g. When dried, the beans from each pod weigh between 1.5 and 2 oz (42–56 g). Although yields can vary greatly, the average tree produces 20–30 pods, so each tree’s output is between 2 and 3 lb (0.9–1.4 kg) of commercial cocoa beans. Mature cacao pods turn yellow, orange, or purple in color. The pods are split open and the beans and pulp scooped out and heaped into boxes or baskets for fermentation (anaerobic and aerobic). The beans are allowed to ferment for 3–6 days, depending upon the type of beans used, batch size, temperature, and aeration. Aeration (turning) of the beans promotes bacterial activity and ensures uniform fermentation. Fermentation and drying processes have major influences on the quality of the beans used in making chocolate.

The beans are subsequently dried (naturally or mechanically) to a moisture content of less than 8% to prevent mold growth, with the optimum being 6–6.5%. Cacao beans must be cleaned before processing to produce a wholesome product with minimal microbiological risks and to remove extraneous materials. On a dry basis, the beans are approximately 87.1% nib (cotyledons), 12.0% shell, and 0.9% germ. The nib contains about 55% cocoa butter fat (Hofberger 1999b). Cocoa beans arriving in the United States are usually inspected for mold, infestation, filth, degree of fermentation, and bean size. They are also fumigated at the ports when received. They should be stored in cool, dry, and well-ventilated warehouses to maintain quality.

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COCOA BEAN PROCESSING

There are several options on how to process the cocoa bean. They all involve the removal of the shell and a roasting step. The roasting process results in the development of the flavor and aroma of the beans. There are several methods, which includes whole bean, nib, and chocolate liquor roasting. Roasting can take anywhere from 15 min to 2 h. Whichever roasting method is used, the nibs are separated from the shell (winnowing). Depending upon the degree of roast, the final nib moisture ranges from 1.5–3%. The traditional method of roasting involves the whole bean. The beans enter a gas-fired revolving drum with various air flows and a cooling section. Temperature and length of roast will depend on equipment, flow rates, type of beans, size of beans, and the flavor desired. Cooled roasted beans will then go through a cracking step to break the nib into large pieces. Winnowing machines will use density differences and sieving to separate the nibs from the shell. Federal standards allow no more than 1.75% shell in the nib portion used for chocolate production. Cocoa-bean shells have little commercial value and are used for mulches, fertilizer, fuel, bedding, and in some cigarette blends. The germ portion is also removed because it is hard and gritty. A common approach to roasting cocoa beans is to rapidly heat the exterior of the beans with infrared heat. The shell expands from the unheated nib portion, where it is easily removed by winnowing. The nib is then roasted in a similar manner to the whole cocoa beans. Several advantages to using this method include lower microbiological count, less fat migration to the shell portion, and better separation between the shell

and nib. The third method of roasting involves grinding raw cocoa nibs into a liquor. This liquor is then heat treated (i.e., roasted) at various times and temperatures to produce the desired finished product. This procedure is said to result in a product with uniform flavor and color. Unlike the two previous methods where large, small, and broken beans may be over- or under-roasted due to size differences, the liquor roasting method has one common heat treatment. After roasting, the nibs are ground to a liquid state called chocolate liquor. The heat and friction from the grinding process will rupture the cell walls of the nibs to release the valuable cocoa butter. This liquor (containing approximately 55% cocoa butter) will solidify upon cooling. Nib grinding carried out using several methods, with most manufacturers using a combination of methods to obtain the desired particle size with the maximum available cocoa butter. Micro pulverizers (often called hammer mills) are the commonly used first step in the grinding process. Although they can be used to produce fine particle size liquor, other mills are often used for final size reduction. This final degree of fineness is important to maximize the amount of free cocoa butter available for viscosity reduction in chocolate, pressing of liquor into cocoa cake and butter, and particle size of the cocoa powder. Stone mills are commonly used for final particle size reduction. They generally have three pairs of grooved “stones”, with each pair progressively making the liquor finer. Each pair of stones has a stator and rotor that can be adjusted in distance. Liquor enters the center of the stones and discharges at the outer circumference to the next pair of stones. A fine particle size may also be obtained with a ball mill. This equipment consists of a tank containing small metal or ceramic balls. Pre-ground liquor enters the bottom of the vertical tanks and is reduced in size by the rotating motion of an agitator on the balls. A five-roll refiner is the final method that is used to reduce particle size. The ground nibs are introduced to the lower roller and move up due to the rollers rotating in alternating sequence with increasing speed. The processing for cocoa and chocolate are essentially the same in the initial stages. The beans are cleaned, roasted, and shelled. The manufacturing of cocoa and chocolate, however, involve two separate processes (Fig. 29.1).

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COCOA POWDER MANUFACTURING

Cocoa cake and cocoa butter are separated from the hot chocolate liquor by hydraulic pressing (more than 6000 psi). This cocoa butter, flowing out from the press, contains small amounts of cocoa powder, which are filtered out to maintain consistent color and flavor. The butter may be further refined, bleached, and deodorized (via steam distillation) to yield a very bland, clean-tasting cocoa butter. What is left in the press is a cake of cocoa powder (cocoa cake).

The cocoa cake will generally have a fat content ranging from 10–24%. Cocoa powder is the cake ground to the desired degree of fineness – usually as 95–99% will pass through a 200-mesh screen. Powders with less than 10–12% cocoa butter are known as low-fat cocoas. Medium-fat cocoa contains 10–18% fat, and high-fat or “breakfast cocoa” has 22–24% fat. Approximately 95% of the cocoa powders on the market today are the medium-fat variety. The FDA has established Standards of Identity for various types of cocoa products (Table 29.1).

Natural cocoa is cocoa powder that has not been treated with alkali. Van Houten, in 1828, first treated cocoa with the addition of alkali; hence, it is also known as “Dutch” process cocoa. The alkalization process raises the pH of the cocoa powder from 5.2–5.6 in fermented beans to a pH

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of 6.8–7.5. Black cocoas, used for color, may have a pH as high as 8.5 (Minifie 1989c). FDA standards allow a maximum of 3.0% potassium carbonate per 100 lb (45 kg) of nib weight equivalent. Added alkali neutralizes acidity in the cocoa, resulting in a milder, less astringent flavor and a range of colors (from light brown to red and even black). Various formulas, equipment, and processes are used to alkalize the nibs, liquor, or powder. This allows for a wide range of cocoa powders to be produced. As such, alkalized cocoa powders are in greater demand than natural cocoa powder. Table 29.2 lists the various cocoa powder types and their applications.

CHOCOLATE MANUFACTURING

Manufacturing of dark, milk, and white chocolates involves certain basic operations: ingredient mixing, refining, conching, standardization of viscosity, and tempering. Like cocoa powders, the chocolate liquor (white chocolate uses cocoa butter only) may undergo alkalization prior to further processing. The FDA has issued Standards of Identity for milk, dark, and white chocolate (Table 29.1). Many chocolates seen on the market will advertise something like 60% cocoa solids. This is really cocao solids, which includes cocoa butter, cocoa powder, and chocolate liquor. In general, a more intense flavor occurs with a higher percentage of cacao solids.

1. Ingredient Mixing

Chocolate liquor, sugar, cocoa butter, milk products (for milk chocolate), emulsifiers, and flavors are the basic ingredients that are blended together. The result is a paste with a rough texture and plastic consistency. It is often passed through a kneader or plasticizer to improve uniformity prior to entering the conches.

2. Refining

In order to obtain a smooth texture with increased surface area, steel rollers are used to reduce particle size of the mass to 10–40 mm. This process is called refining. The actual size will depend upon the product desired and type of chocolate, with dark chocolate generally having a smaller finished particle size. During this process the resulting mass often turns into a dry paste or powder. The manufacture of milk chocolate is similar to that of dark chocolate. The way milk is added plays an essential part in the process. Milk solids are introduced in the form of milk

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powder or milk crumb, where it is dry mixed with chocolate liquor and sugar. Milk powder is produced by first concentrating liquid milk and drying it into a powder. The crumb process involves blending sweetened condensed milk and chocolate liquor. It is kneaded and dried. Crumb-based chocolates have a unique caramelized flavor based on the Maillard reaction between milk protein and sugars (Minifie 1989e; Stauffer 2000). The term“white chocolate” has been used loosely for a number of years. It is basically milk chocolate with cocoa butter but no chocolate liquor. Cocoa butter is mixed with sugar, milk solids (a white crumb can be made from cocoa butter), emulsifiers, and flavors. Use of a mild-flavored cocoa butter is preferred because the flavor ofwhite chocolate is quite delicate. White chocolate is also more prone to oxidative rancidity than milk and dark chocolate.

3. Conching

After refining, the mass is transferred to large shear mixers (conches). This is the last manufacturing process where texture and flavor are affected. Time, temperature, moisture control, and shear manipulate the process. Some of the benefits of conching are (Hofberger 1999b) as follows:

. Improved rheology/reduction in viscosity (less cocoa butter needed);

. Elimination of harsh volatiles for a mellower taste;

. Removal of moisture (reduces lumping and graining);

. Improved mouthfeel (smoothes sharp particle edges).

Additional cocoa butter, flavors, and emulsifiers may be added during this process. Conching times will vary depending upon the formulation and final product desired, but can vary from 10 to 12 h up to several days. Conching temperatures range from 120 to 1608F (49–718C), and sometimes up to 1808F (828C). The higher conching temperature gives the final product a caramelized flavor that is different from milk crumb caramelized flavor (Minifie 1989f).

4.Viscosity Standardization

Standardization of product viscosity is one of the final steps in the manufacturing of chocolate. The development of automatic molding and enrobing equipment requires precise control over the fluidity or viscosity of the chocolate. It should be noted that the viscosity of chocolate increases with the presence of free moisture in chocolate. Thus, general moisture tests will not necessarily provide pertinent information for viscosity. Minute amounts of water or steam from leaking equipment, improper storage (humid conditions), and rework can affect the overall performance of the chocolate. Chocolate is a non-Newtonian liquid in that its viscosity (internal friction of fluids) is affected by the presence of solids in suspension, as well as by temperature. Once chocolate starts to flow, its viscosity will decrease with an increase in the shear rate (Minifie 1989d; Hofberger 2000). The United States is the only country that still uses degrees MacMichael to decribe chocolate viscosity. The MacMichael viscometer is a single-speed rotational instrument. It works on the following principle: A metal cylinder is suspended on a torsion wire, which, in turn, is immersed in a cup of chocolate at a given temperature. As the cup rotates, twistingmof the wire is measured by a scale. The main drawback of the MacMichael method is its inability to provide full information on the flow properties of different chocolates.

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In other parts of the world, viscosity is usually measured in centipoise. A Brookfield viscometer can determine plastic viscosity and yield values accurately. Results using a Brookfield can be converted to degrees MacMichael. Table 29.3 shows a range of chocolate viscosities and their typical applications. Viscosity alone will not indicate how the product will perform in the handling process. Two terms that help to describe flow character are yield value and plastic value. Yield value (YV) is the force required to initiate the flow of chocolate. Plastic viscosity (PV) is the force required to maintain the flow of chocolate once it has started to move.

A high YV is important in maintaining decoration marks and the prevention of “feet” on enrobed goods. A low YV is desirable for molded products to properly shake out air pockets (Minifie 1989d; Hofberger 2000). Several factors can affect viscosity and rheology. Smaller particle size in a constant formula will give a higher viscosity. Lecithin is thus an excellent emulsifier as it exhibits both lipophilic and hydrophilic properties. The hydrophilic groups attach themselves to the water molecules on the surface of the sugar particles and reduce friction, increasing particle mobility and thus lowering viscosity (Minifie 1989d). This reduction in viscosity can also decrease the need for more expensive cocoa butter by as much as 5% (Hofberger 2000). In the United States, the addition of lecithin or other emulsifying agents is limited to 1% by weight.

5. Tempering

Tempering is the controlled cooling of melted chocolate with agitation to promote the formation of small stable fat crystals throughout the chocolate. Besides agitation, time and temperature are also critical factors in the tempering process. Cocoa butter is a polymorphic fat in which the crystals have different characteristics, melting points, and stability. There are four major types, g, a, b0, and b, with b being the only stable form. The unstable forms will eventually recrystallize into the stable b form (Minifie 1989b; Kattenberg 2001) (Table 29.4). Stable cocoa butter crystals will provide the following desired properties (Hofberger 2001):

. Snap,

. Good gloss,

. Proper texture,

. Bloom resistance,

. Contraction for demolding, and

. Less permeable barrier (increased shelf-life).

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The cocoa butter used in chocolate manufacture will affect the physical properties of the chocolate. The origin of the bean will also affect its quality. Attributes affected include hardness, texture, mouthfeel, and melting point of the butter. Tempering can be conducted manually or in an automatic tempering unit to form stable fat “seed” crystals. There are many types of units available using various methods to achieve the goal. In general, chocolate tempering involves heating the chocolate to approximately 110–1158F (43–468C) to melt the fat crystals, followed by cooling with agitation to between 80 and 848F (27–298C), and subsequently reheating to about 86–888F (30–318C) before molding or coating. In general, dark chocolates are tempered about 1–28F (0.5–1.08C) higher than milk chocolate (Hofberger 2001). However, exact temperatures and procedures will depend upon the tempering equipment and type of chocolate used. The four most common types of automated temperers include the following.

. Tempering kettle. This is primarily a batch operation where the proper temperature is maintained by a jacketed water kettle, and agitation necessary for crystallization is provided by the sweeping action of the stirrer.

. Plate heat exchanger. The cooling and warming cycle is accomplished when chocolate passes over a series of jacketed plates. The scraping action of the plates allows rapid growth of small crystals. This is currently the most popular and common type of temperer.

. Screw-type temperer. As chocolate passes through a jacketed shell, the scraping action of the screw provides the agitation necessary for seed formation. Different sections of the shell provide the proper temperatures needed.

. Bowl-type temperer. This method uses dry heat to melt chocolate in a rotating bowl. Chocolate is melted to _1058F (40–418C), and then cooled by ambient air to approximately 868F (308C ). During this process, tempered pieces of chocolate are placed in the back half of the divided bowl to provide the proper “seed” crystal. After the chocolate is sufficiently tempered, the temperature is raised to 88–908F (31–328C) to prevent overtempering. This method has the advantage of not requiring external water and plumbing. Room temperatures must be kept at 738F (238C) or less to provide for proper tempering. These units are gaining in popularity for very small candy shops where the use of “real” chocolate is desired. The viscosity of the chocolate increases in proportion to the increase in seeding during tempering, thus chocolate must be used fairly quickly, or carefully heated to remelt some of the seed to prevent overtempering and achieve a steady state of temper. Overtempered chocolate may cause problems such as dull finish, excessive air bubbles, and poor mold release because of reduced contraction of the chocolate. Undertempered chocolate will also have poor mold release and will have a tendency to “finger print”, and have premature blooming. Once the desired pieces of chocolate are formed, the chocolate should be cooled gradually to prevent future problems. Initial cooling temperature

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should be approximately 658F (188C) with minimal air movement. This is necessary for the continued formation of stable crystals and to prevent case hardening or the formation of a “skin”. Temperatures can gradually be decreased to about 458F (78C) with increasing air velocity. Final cooling temperature before packing should approach that of the room temperature (about 688F) (208C).

One must take into consideration the heat load of the product and adjust air temperatures and velocities accordingly when sending product through a cooling tunnel. Small pieces of chocolate will set at a faster rate than large molded blocks. The temperature on the discharge end should be higher than the dew point to prevent condensation on the chocolate. At this point, the chocolate may appear solid. But, in fact, only about 70 to 75% of the cocoa butter is crystallized. It will take about 48 h for all of the cocoa butter to crystallize. So packing and storage conditions are still an important consideration (Hofberger 2001).

6.Enrobing

The mechanized form of hand dipping is enrobing. By completely covering the center with chocolate, the shelf-life of the product may be extended. This is primarily applicable to centers that, if not covered, could be prone to moisture loss, oxidation, or microbial action. To ensure a firm bottom, manufacturers often first pass the centers through a prebottoming step. The prebottoming step can be done with chocolate or compound coatings. The advantage of using compound coatings is that they may be set up faster and no tempering is needed. The prebottoms need to be set before entering the enrober. This is especially important when lauric-based compound coatings are used, because they will most likely eventually bloom due to fat incompatibility. Maintaining a consistent temper in the enrober will affect the coverage and appearance of the final product. Most enrobing units today utilize active tempering/detempering equipment. Enrobing equipment with active tempering may have either inboard or outboard tempering. For smaller operations, an inboard unit that is part of the enrober provides for an inexpensive and compact unit. For larger operations, an outboard or separate tempering unit would be more suitable. It can also be fitted with a screen to filter inclusions coming from the center mass. Both methods follow the principle of enrobing centers with a tempered coating. The excess coating is removed, detempered, and retempered before entering the enrobing process again. This helps to prevent overseeding of the chocolate in the enrober. Chocolate temper should be taken at the enrober and not at the tempering machine, where line temperatures and residence times from the tempering machine to the enrober can significantly affect the amount of seeding. It is important that the centers entering the enrober be maintained at 70–758F (21–248C), and the enrobing chocolate have the desired viscosity and rheological properties. Warmer centers may lead to possible bloom problems as the heat tries to escape from the interior of the enrobed product. Cold centers may also cause blooming and cracking of the coating shell due to expansion of the center mass as it warms.

The prebottomed centers are conveyed on a wire belt through a curtain of tempered chocolate, coating the top, sides, and bottom as well. The excess coating is removed through the action of adjustable vibratory shakers and forced air blowers. The blowers will often leave a desired rippled decoration on top. Prior to transferring to the conveyor belt, the product passes over a rotating detailer rod to remove the trailing “tail” at the end of the enrobed piece. For maximum shelf-life, it is important that the centers be completely covered, with no pinholes.

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7.Cooling

After enrobing, the product enters a cooling tunnel to allow the coating to harden. To avoid blooming problems, temperature changes should be gradual, and the relative humidity properly controlled. If the dew point is lower than room temperature, moisture could condense on the product and cause sugar bloom during storage. There are three basic types of cooling tunnels that allow for the proper crystallization of the coating: Convection tunnels use chilled air moving in parallel under the product belt. The cold air enters near the discharge end of the tunnel, and moves counter current to product flow, and is removed near the entrance to the cooling tunnel. Multi zone tunnels have chilled air moving transversely to product flow in specific sections. These types of coolers allow precise temperature control and even have the capability of re-warming the product prior to discharge to prevent condensation.Radiant cooling tunnels utilize black matte absorption plates. They absorb the radiant heat fromthe chocolate that supposedly helps to prevent case hardening of the chocolate. To increase the cooling rate, many radiant tunnels also use convection air movement.

Chemical and Allied Substances Used in the Confectionery Industry

1. ACIDS

2. BUFFER AND OTHER INORGANIC SALTS

3. ANTIOXIDANTS

4. RELEASE AGENTS, EMULSIFIERS

5. SOLVENTS

6. INVERTASE CONCENTRATE

CHOCOLATE BLOOM PROBLEMS

The most common problem encountered during chocolate storage is probably blooming. It is a defect that manifests itself as a grayish-white film on the surface of the product. In most instances the eating quality is not affected; however, the appearance is not very appetizing. Bloom may occur anywhere from a few hours after production to several months later (Seguine 2001). There are basically two types of bloom – sugar and fat.

Sugar Bloom

Sugar bloom occurs less frequently than fat bloom and its appearance may look like fat bloom. It occurs when the surface of the chocolate is exposed to moisture or high humidity and then dries out. The surface film of water dissolves some of the sugar particles in the chocolate, which then recrystallizes upon drying into a dull grayish-white haze. It commonly occurs in chocolate products emerging from a cooling tunnel into a warm and humid room. It also may occur when product is brought out of cold conditions and subjected to warmer, humid conditions without proper packaging and time to gradually bring it up to room temperature. In general, sugar bloom feels dry to the touch and does not melt, which differs from fat bloom.

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Fat Bloom

Fat bloom is the visible accumulation of large cocoa butter crystals on the chocolate surface, which may give it a greasy surface texture that melts readily when touched. It may be accompanied by numerous mini cracks that give it a dull grayish-white appearance. These changes are primarily due to the polymorphic nature of cocoa butter and the migration of liquid fat (McCarthy and others 2003). Some factors causing chocolate bloom are listed in Table 29.5.

STORAGE AND HANDLING

Like many other foods, chocolate flavor will change over time, resulting in a more balanced flavor profile. In general, most chocolates should be contained in a nonpermeable barrier for protection from oxygen, moisture, and light. Ideally, chocolate should be stored at 65–688F (18–208C) and less than 50% relative humidity. Dark chocolate is less prone to moisture absorption during storage than milk chocolate (Minifie 1989g; Hofberger 1999b; Urbanski 2001). As it is fat-based, it will readily absorb off-odors so chocolate should be stored in an odor-free environment. Chocolate will also pick up odors from packaging materials, printing inks, as well as odors generated from the heat sealing or shrink-wrapping process. Advances in packaging technology now include water-based cold-seal adhesives that not only eliminate the potential for heat-damaged chocolates but are also low in odor, thus eliminating or reducing the possibility for the development of off-flavors or smells (Barry 2003). Properly stored, solid chocolate should have a shelf-life of one year of more. Chocolate can be frozen for even longer storage; however, care must be taken when bringing it back to room temperature from the frozen state to avoid condensation. If chocolate ismanufactured fromclean beans under sanitary conditions, its microbial count should be low due to its low water activity (aw) level. However, chocolates may become contaminated by some of the ingredients and equipment used, and improper storage conditions. Moisture can be introduced into the product during its manufacture (such as equipment leaks or improperly dried equipment) or during storage under damp conditions. This may lead to mold problems. Equipment leaks will produce a high-viscosity chocolate that is readily apparent and should not be used for further processing. Moisture on the outer surface of the chocolate from improper storage conditions can also cause mold growth. Rancidity is generally not a problem in milk and dark chocolates because of the natural antioxidant properties of undeodorized cocoa butter. Rancidity can be found on occasion in white chocolate and

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compound coatings and is catalyzed in the presence of air, moisture, light, heat, and some metals. With oxidative rancidity, the fats or oils exposed to air produce objectionable flavors due to the formation of aldehydes and ketones. The addition of synthetic antioxidants will help inhibit this reaction although some fats contain natural antioxidants as well (Minifie 1989g).

Hydrolytic rancidity, also known as soapy rancidity, is due to the lipid hydrolysis of fat into glycerol and fatty acids with the production of an off-flavored soapy taste. Lipases may be present in ingredients such as coconut, milk products, egg albumen, and cocoa. However, not all lipase activity will result in a soapy flavor. If possible, it is recommended that ingredients susceptible to hydrolytic rancidity be heat treated to inactivate the enzyme. Fats containing lauric acid, even a trace amount, will yield a soapy flavor.Coconut oil and palm kernel oil contain 40–50% lauric glycerides, and butter fat contains 2–6%. Cocoa butter and palm oil do not contain lauric acid (Minifie 1989g).

NUTRITIONAL VALUE

Chocolate is not a major source of dietary fat, but it does contain fat. The majority of the fat comes from cocoa butter and is composed mainly of three fatty acids: 30–37% of the monounsaturated fatty acid is oleic acid (18 : 1), 32–37% of the saturated fatty acid is stearic acid (18 : 0), and 23–30% of saturated fatty acid is palmitic acid (16 : 0). It also contains 2–4% linoleic acid (Nacional de Chocolates 2003). Although stearic acid is classified as a saturated fat, it does not appear to raise cholesterol levels the way other saturated fatty acids do (Chocolate Information Center 2003a). Table 29.6 shows the USDA nutrient content of several types of chocolate.Chocolate has also been noted recently to contain relatively high amounts of polyphenols, in particular the flavanols, catechin, and epicatechin. Polyphenols are found in the plant kingdom and exhibit antioxidant activity that is thought to reduce the risk of some human diseases. The levels found in chocolate and related products will depend upon cocoa bean variety, fermentation, and subsequent processing and formulation (Chocolate Information Center 2003b; International Cocoa Organization 2003a). A class of alkaloid molecules known as methylxanthines (such as caffiene, theobromine, and theophylline) occurs naturally in a number of plant species. They exhibit similar pharmacological properties. They are mild stimulants and possess mild diuretic properties (About Chemistry 2001; International Cocoa Organization 2003b). A common belief is that chocolate contains a lot of caffeine. However, caffeine is the primary alkaloid in coffee, theobromine the primary alkaloid in chocolate, and theophylline the primary alkaloid in tea. A comparison of the caffeine contents in chocolate and coffee is presented (Table 29.6). A food allergy is a reaction by the body’s immune system to a substance, usually a protein, in the food. According to the National Institutes of Health, approximately seven million Americans (more children than adults) have a true food allergy. Eight food allergens account for 90% of all allergic reactions. These include milk, eggs, peanuts, tree nuts, soy, wheat, fish, and shellfish (Chocolate Manufacturers Association 2003b; National Confectioners Association 2003). An allergy to chocolate itself is uncommon; however, the addition of other ingredients may cause an allergic reaction. Chocolate is one of the most popular flavors, enjoyed by millions of people in a variety of ways, from beverages, to main dishes, sauces, baked goods, and of course confections. Eaten in moderation it can be part of a healthful diet.

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MILK CRUMB

Milk crumb is a homogeneous blend of cocoa solids, milk solids and sugar. It has found wide acceptance in the manufacture of chocolate as its use avoids the necessity of adding dried milk powder. Although milk crumb is more expensive, when considered on a comparable solids content basis, the milk chocolate produced is of better quality and improved cocoa flavour; it has a tendency to be harder than that manufactured using equivalent amounts of cocoa bean, dried milk and sugar. The method of manufacture is depicted in Fig. 13

A typical composition for a commercial milk crumb is as follows:

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Part-C (Tea, Coffee and Spices)

1. Tea: History, introduction, world tea production and growing, tea cultivation and production in Nepal, chemical composition of tea, manufacture of tea, grading and specification, quality and storage of tea, factors affecting tea quality.

2. Green and partially fermented tea.

3. Coffee: History, introduction, production statistics, cultivation, chemical composition of coffee, processing technology, agglomeration, packaging and storage, quality control.

4. Spices: Ginger, turmeric, chillies, cardamom(large), cinnamon, black pepper.

(a) Production, cultivation and uses.

(b) Chemistry and Technology.

-Special attributes- flavour components.

-Chemical composition.

-Processing, Drying & storage

-Extraction of oleoresin, essential oil.

Tea

Introduction

Tea is a stimulating and refreshing beverage consisting of an infusion of the processed and dried leaves of the plant, Camellia sinensis.Tea is the most popular beverage consumed by three-fourth of the world’s population. Its popularity is due to its excellent flavour and healthful effects on human body. Tea is an interest of food technologists, biochemists and organic chemists about the final product and its chemical composition. The principal flavour components of tea are caffeine, tannin yielding components and small amounts of essential oil. Caffeine gives stimulating effect, tannin gives colour, body and taste to the extract and essential oil gives aroma.

Tea is an aromatic stimulant, containing various polyphenols, essential oils, and the alkaloids caffeine and theobromine. The concentration of caffeine in tea ranges from 2.5 to 4.5 per cent, as contrasted to an average concentration of about 1.5 per cent in coffee.

Tea has no nutritive value. The proteins present in tea leaves are rendered insoluble in brewing. Tea infusion contains negligible quantities of fat and carbohydrates. Tea as a beverage is consumed for its stimulating value. A tea infusion provides only 4 cal. per cup but with the addition of a table spoon of milk (10 calories) and a lump of sugar (25 calories), it provides about 40 calories. One pound of good tea (0.45 kg) may contain up to 245 grains (15.9g) of caffeine and is sufficient to make 200 cups of the beverage. Caffeine stimulates gastric secretion and hence may aid digestion to certain extent. It has a delaying action on the emptying time of the stomach and hence it allays a sense of hunger. Excessive consumption of tea is likely to be harmful due to high intake of caffeine. Caffeine in excess produces insomnia; causes irritability and rapid heart action. It also increases excitability of the nervous system particularly in the very

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young and the old. Since it is a rich source of oxalic acid, excessive consumption of tea may lead to the development of renal calculi.

The worldwide consumption* pattern of tea is attributed by the pleasant taste and aroma as well as its healthful effects on the human body. It has been claimed that tea has a positive effect on digestion, nervous system, blood vessels and cardiovascular function. It decreases blood pressure and increases the vital energy of human. Green tea is considered more beneficial than fermented teas. The total polyphenols in green tea is higher than that of black tea manufactured from similar leaf. Tea polyphenols normalize thyroid hyperfunction, strengthen the walls of blood vessels and regulate their permeability. Green tea can cure scurvy due to its vitamin P content. Green tea infusion shows anti bacterial activity and is an effective cure against dysentery. Green tea is also reported to inhibit the growth of cancer tumours.

*Per capita consumption of Tea in different countries. Following table indicates the per capita consumption of Tea in different countries.

S.No. Name of the Country KG per person

1 Ireland 3.00

2 United Kingdom 2.50

3 Turkey 2.10

4 Iran 1.50

5 India 0.70

6 United States 0.30

7 Australia 0.90

8 New Zealand 1.10

9 Qatar 1.50

10 Sri Lanka 1.30

11 Kuwait 2.10

12 Syria 1.35

13 Nepal 0.35

History

Tea has been consumed since antiquity. The origin of the beverage remains unknown. The Chinese are recognized as being regular consumers by the 5th century A.D. Tea was first drunk

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for its supposed medicinal properties, but subsequently became accepted merely as a refreshing beverage. The drinking habit gradually spread along the trade routes of Asia minor and was introduced to Europe by Dutch traders during 17th century. In England tea overtook coffee in popularity during the 18thcentury and has been established as the National drink since that time. Details of preparation and cultivation of tea was written by LU YU in 780 A.D. tea was introduced in Japan -1000 A.D,India-1818 A.D, Sri Lanka-1880 A.D. and Nepal 1920 B.S. Chief consumer of tea is U.K. and great tea market is London.

World Tea Production and Growing

Today’s major tea producers are India, China, Sri Lanka, Indonesia, Kenya, Malawi, Zimbabwe, Papua New Guinea, Bangladesh, Mauritius, the Democratic Republic of the Congo, and Cameroon. Tea is also grown in South America, Japan, Australasia, Eastern Europe, and the Middle and Far East, but mainly for domestic consumption.

India, a major tea producer, with more than 400,000 hectares under tea cultivation, produces approximately 30 per cent of the world’s tea, and accounts for 14 per cent of the world tea exports. Indian teas are seasonal, with plucking undertaken from March through to October. They range from the low-grown indigenous Assam, discovered around 1832 by the Bruce Brothers, to the high-grown teas of Darjiling, which were originally planted from seeds and seedlings imported from China.

Sri Lanka is the world’s largest tea exporter, accounting for 21 per cent of the world tea exports. Today, Sri Lanka has more than 200,000 hectares under tea cultivation, and, because of its geographical position, tea can be plucked throughout the year. Kenyan teas are probably the best known of the African teas, as Kenya caters for both the speciality and the blended-tea market. Kenyan teas were being sold at the London auction. Kenya is a fertile land with a climate that allows the growing and picking of tea throughout the year. It accounts for 18 per cent of world tea exports.

China is the second largest tea producer and exporter after India and Sri Lanka respectively. It retains the majority of its tea produce for home consumption, exporting about a quarter of its annual tea yield, which accounts for 18 per cent of the world tea exports.

Agronomy

Tea, common name for a family of mostly woody flowering plants, for certain species of the Camellia genus within the family, and for the beverage made from the leaves of the Camellia sinensis plant. The family, which contains about 520 species placed in 28 genera, is distributed through tropical and subtropical areas, but most species occur in eastern Asia and South America.

The plant Camellia sinensis is considered the most important plant in the Camellia genus, particularly from a commercial point of view. It is indigenous to both China and India, hence the use of the tea trade terms “China jat” or “Indian jat” to distinguish the origin of the original tea bushes on some of the older tea estates. Today, these two jats are considered the main varieties, of which there are many hybrids. In its wild state, the tea plant grows as a tree, reaching some 30 m (98 ft) in height. Cultivated tea is grown as a bush, about 1 m (3 ft) high, with continuous vegetative growth. Leaves of the tea bush are, generally, serrated, shiny, and pointed. The China

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jat, classed as an erectophile (leaf angle less than 50 degrees), has a small leaf that is normally darker in colour than the larger, broader, and lighter green leaf of the Indian jat, classed as a planophile (leaf angle less than 70 degrees).

Tea varies in flavour and characteristics according to the type of soil, altitude, and climatic conditions of the area in which it is grown. Processing methods also affect the flavour and characteristics, as does the blending of different teas from different areas.Tea is grown commercially in a large number of countries, the northernmost being Georgia in the former Soviet Union, and the southernmost being South Africa and Argentina. India, China and Ceylon are the three major producers, but significant quantities are also grown in Java, Sumatra, Japan as well as in parts of Africa.

Today, tea is grown on smallholdings or estates. In smallholding tea areas, cooperatives are formed to build a tea-processing factory central to a group of smallholders. The larger tea estate is a self-contained unit, often covering hundreds of hectares, housing its own factory, tea-growing area, and even staff houses.

Under modern cultivation the tea bushes are maintained at waist height for ease of plucking, and are grown from cuttings or clones, which are carefully nurtured in nursery beds, and trained to grow in a fan-shape until ready for planting out. Young bushes are planted about 1.5 m (5 ft) apart in rows approximately 1 m (3 ft) apart. This allows easy access to the bushes for both pluckers and gardeners. In the higher altitudes these rows follow the contours of the hills or mountainsides to avoid soil erosion. On some of the higher estates and small holdings terraces are built, again to avoid soil erosion.

Tea varies in flavour and characteristics according to the type of soil, altitude, and climatic conditions of the area in which it is grown. Processing methods also affect the flavour and characteristics, as does the blending of different teas from different areas.

Climate and soil type

Tea is grown commercially in a large number of countries, the northernmost being Georgia in the former Soviet Union, and the southernmost being South Africa and Argentina. India, China and Ceylon are the three major producers, but significant quantities are also grown in Java, Sumatra, Japan as well as in parts of Africa.

Tea is grown on smallholdings or estates. In smallholding tea areas, cooperatives are formed to build a tea-processing factory central to a group of smallholders. The larger tea estate is a self-contained unit, often covering hundreds of hectares, housing its own factory, tea-growing area, and even staff houses.

It is generally accepted that air temperatures in the range 18-300C are optimal for shoot growth. The minimum air temperature for shoot growth appears to be 13-140C, while net photosynthesis and growth are both markedly reduced at temperatures in excess of 300C. Soil temperature is also important and optimum growth occurs between 20 and 250C.

A high rainfall and high air humidity are also essential for shoot growth and in most areas an annual rainfall of about 1800mm, distributed more or less evenly over the year, is necessary for

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continuous crop production. Cultivation of Camellia is not usually possible where the annual rainfall is less than 1150mm unless irrigation is used.

Camellia is grown in a wide variety of soil types, developed from different parent rock under different climatic conditions. Types which support the commercial cultivation of tea include alluvial soils, drained peat, sedimentary soils derived from gneiss and granite, and soils derived from volcanic ash. Growth of Camellia is favoured by acidic conditions, a pH value of 5.0-5.6 being considered optimum. Tea will grow in a soil with a pH value as low as 4.0, but soils of pH value only marginally above 5.6 are considered unsuitable unless pH adjustment is employed. Soils of pH values above 6.5 are not amenable to treatment and cannot be used for commercial tea growing.

Commercially grown Camellia has a low requirement for phosphorus, but potassium is important as a consequence of its intimate relationship with nitrogen metabolism. There are also relatively high requirements for calcium and magnesium. Tea has only relatively small requirements for sulphur, which is usually a constituent of nitrogen fertilizers, but deficiencies occasionally occur due to the use of unsuitable soils in propagation nurseries.

Camellia has a relatively high requirement for zinc and deficiencies can occur. Localized deficiencies have also been reported for copper and boron. Copper deficiency also has significance in the post-harvest behaviour of tea, low levels of a copper –protein enzyme resulting in failure of the fermentation process. Aluminium is also an essential for the tea plant.

The physical properties of soil are of importance in determining suitability for tea cultivation. In general, soil should be deep and well drained and while tea can be grown in shallow soils with a high water table, management is difficult. The soil should be of good water holding capacity to minimize problems due to low rainfall and absence of irrigation.

Tea plants are normally raised in a nursery before being planted out in fields. The planting materials are either seed or clones. Tea Research Association, Tocklai Experimental station Assam produces seeds and clones. Tocklai vegetatives with high yield and average quality are TV22 , TV23, TV 25, TV26 and TV30, while TV21 is one with high quality and average yield. Similarly Tocklai seeds with high yield are TS450, TS462, TS463 , TS491, and TS520.

Tea Cultivation and Production in Nepal

Nepal has a long history of Tea cultivation, initiated with the establishment of Ilam Tea Estate in the Hills of Ilam District in 1863 and Soktim Tea Estate in the plains. It is believed that Tea plantation in Nepal started within the same Decade, when it was introduced in Darjeeling Hills of India. Mr. Gajaraj Singh Thapa is the remarkable name in Nepalese tea history who planted tea first time in Ilam District of Nepal. It's the same Geographical and Topographical conditions with an open border to Darjeeling in India. First Tea Plantation at private Tea sector in Terai was established in 1959 and was registered with the name of Bhudhakaran Tea Estate.

Nepal Tea Development Corporation was established in1966 by Government of Nepal. The Government of Nepal declared the five districts i.e. Jhapa, Ilam, Panchthar, Terhathum and Dhankuta of the eastern development region as 'Tea Zone' in 1982.

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The total area under tea plantation estimated as at 2007 is 16400 hectares with the production volume of 152 million kgs. It is providing direct employment to 40 thousand people. The climatic conditions are suitable for Orthodox tea in hilly range and CTC (Crush-Tear-Curl) at Terai. Nepal has initiated producing export quality Green Tea.

Tea in the private sector comprises of small farmers, small processing factories and big Tea Estates with tea processing factories. There are 140 Registered Tea Estate which contribute 85 % of the National production volume. Nepal has 40 Tea processing factories in private sector. They produce both orthodox and CTC Tea.These factories do not have their own Tea Plantation but depend on the small farmers for the green leaves to run their factories. Further a rapid increase in Tea area at small holders’ level is anticipated due to the market of their production.

Basically there are two kinds of tea packaging industries operating in Nepal. The first one being the private Estate owning tea packaging unit of itself and second are the ones who operate their Industry buying bulk from private tea estates and the tea imported from outside.

Forecasts:

There is about 16420 hectares area under tea, majority of the plantation is done by small holders. Present Tea plantation is in small holders dominations. Future target is set to extend plantation to 40 thousand hectares with expected harvest of 46 million kg of Tea which could be a worth of 247 million dollars. This will generate employment for 102 thousand people in rural areas which will boost up the rural economy opening up new development opportunity.

Following table is an expected growth of Tea plantation

SN Type of Tea

Area in Hectares

Total Production in Million Kg.

Domestic Consumption in million kg.

Export in million Kg.

Value of Export in million

Value of domestic consumption in million

Total Value in million

1 Orthodox 30133 30.13 3.01 27.11 197.95$ 13.20$ 211.15$

2 C.T.C. 10652 15.98 9.40 6.57 14.40$ 20.59$ 34.99$

Total 40785 46.11 12.41 33.68 212.35$ 33.79$ 246.14$

This way our strategy is with the ambition to the economic development through the development of Tea industry we expect, Nepal can stay in the front line in the world in orthodox tea production in the world market.

Nepal tea and coffee development board (ntcdb@hons.com.np )

The National Tea and coffee Development Board is commodity board established on 1993/06/02 under Tea and Coffee Development Board Act 1992 in Nepal. The Broad objective of this board is to promote and strengths Tea and Coffee sector through policy formulation, Technical and managerial Support.

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1. To Formulate & implement the Tea and Coffee Development policy.

2. To identify problems and ways to solve them for the development of Tea & Coffee Sector

3. To manage import of Tools & Equipment for the Tea & Coffee production process.

4. To establish Tea & Coffee Training and Research center and provide Technical knowledge and skills to people and organization involved in Coffee and Tea sector.

5. To conduct studies for the development of Tea & Coffee sector.

6. To co-ordinate with Organizations related to Tea & Coffee sector.

7. To support Tea & Coffee Industries

Organizational Structure

EXECUTIVE COMMITTEE

Under the chairmanship of the Minister/Minister of State for Agriculture and Co-operatives, an Executive Committee (EC) is formed with 17 members representing from various ministries, private sector,organization and farmers. The Executive Director is nominated by Government of Nepal and acts as member secretary.Representation to EC is from the following sectors

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1. Minister or State Minister for Ministry of Agriculture and Co-operatives--Chairperson

2. Nominated person from the Government - Vice Chairperson

3. Representative - Private Tea Producer.

4. Reprehensive - Private Coffee Producer.

5. Representative - Small Tea Farmer.

6. Representative - Small Coffee Farmer.

7. Representative - Nepal Tea Producers Associations.

8. Joint Secretary - Ministry of Agriculture and Co-operatives.

9. Joint Secretary - Ministry of Finance.

10. Joint Secretary - Ministry of Commerce and Industries.

11. Executive Director - National Agriculture Research Council.

12. General Manager - Agriculture Development Bank.

13. General Manager - Nepal Tea Development Corporation.

14. Executive Director - Trade promotion Center.

15. Executive Director - National Tea & Coffee Development Board – Member Secretary

Note: The committee shall nominate representative one each from Tea & Coffee Industry workers.

SUPPORT AREAS

1. Policy Formulation.

2. Feasibility study of Tea and Coffee.

3. Support of farmers and coffee and tea Industries.

4. Capacity Development of Coffee and Tea professionals.

5. Market survey at National and International level.

6. Tea and Coffee Quality management.

Achievements

Government of Nepal accepted and adopted the National Tea Policy-2000 on 9th November 2002 which will be a mile stone in tea development history of Nepal.

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The Fourth Asia International tea conference took place in Kathmandu Nepal with a slogan of "Tea in Asia- a vision of 2010" on the 6th to 7th October 1999, there were participants from Srilanka, India, Bangladesh, Thailand, Japan and Russia. By this event, Nepal got a glory to be introduced as a quality tea producing country in the world.

Government of Nepal has accepted & adopted national Coffee Policy 2003

International Tea interface with special emphasis of the three E's (Economy, Environment & Employment) regarding tea industry was held on 25-27, April 2001 at Kathmandu, Jointly organized by NTCDB, AEC, HOTPA & TPA has been successfully conducted with the active participation of Sri Lanka, Bangladesh, Pakistan, Japan, Germany, UK and India.

Leading companies and organizations related to tea industry of Nepal in the leadership of National Tea and Coffee Development Board participated in the world-O-cha (Tea)-festival at Sizuoka & Tokyo of Japan held on 2nd to 8th Oct 2001 for the market promotion of Nepal tea. At the festival Nepalese tea traders got an excellent opportunity to develop business relationship with Japanese as well as several other international tea enterpreneurs & traders.

Government of Nepal has declared the Baisakh 15th as a National Tea day. Similarly, Every Mangier 1(one) has been declared as National Coffee Day.

Nepal Tea Festival London-2002 has been celebrated on 21st to 26th July 2002. NTCDB has provided the necessary support to promote the export market of Nepal Tea in Europe. The program jointly organized by National Tea & Coffee Development Board of Nepal Pavilion Company.

On 11th July 2002, NTCDB has been awarded from the London Borough of Ealing with presentation in friendship by his worshipful Mayor Councillor Keiron Gavan for its performance.

National Tea & Coffee Development Board in co-ordination with Department of Postal Service and National Philatelic Beauro has published postage stamp of Tea senerior and the symbol of National Tea Logo worth Rs. 25 keeping in mind the publicity of Nepal Tea in the international market.

National Tea Policy-2000

Objectives:

1. To increase tea production area, (40875 he)

2. To increase tea production, 46111000 kg)

3. To provide employment, (79310 persons)

4. To increase orthodox tea production (by 65%).

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Associations

Nepal Tea Association

Established in 1985, supports promotional activities of Tea packagers and traders with a combine strategy.

Cell Contact: 9851020431

Nepal Tea Producer's Association

Nepal Tea Producer's Association was constituted with the ambition for the development of CTC tea industries.

Cell Contact: 9852671009

Himalayan Orthodox Tea Producer's Association (HOTPA)

To further the development and promotion of Nepal's tea industry the Himalayan Orthodox Tea Planters Association (HOTPA) was formed. HOTPA is a non-profit making association, which aims to develop orthodox tea industry in the hill region, motivating small farmers for plantation and promoting the tea market abroad.

Tel. Contact: 5552743

Cell No. : 9851013022

Nepal Coffee Producer's Association (NCPA)

NCPA is farmers' forum dedicated for the production, processing and marketing of quality coffee through policy lobbying, technical service and institutional strengthening support to farmers groups.

NCPA is active since 1991.It became central federation in 1998. There are 13 districts with more than 15000 farmers associated with NCPA. It has members at different level-Farmer group at community level represents to the District chapter- District Coffee Producers' Association and the District chapter represents to the National level – Nepal Coffee Producers Association.

Central Office Babarmahal, Kathmandu Nepal Phone: 2030063 Fax: 4267238 Email: ncpa@info.com.np

Himaliyan Tea Producer's Cooperatives Contact: 9851078467

Central Coffee Cooperatives Ltd. Email:ctrlcoffee@wlink.com.np

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Chemical composition of tea

The chemical composition of tealeaf is of interest mainly because of the reactions that take place during its manufacture. The compounds that contribute to the strength, colour, pungency, flavour and stimulating properties of the beverage are important constituents. The chemical composition* of tealeaf is very complex. (Table 1)

The following classes of compounds have been identified in the tealeaf.

The polyphenols

Pigments/Flavonids

Proteins and amino acids

Alkaloids(caffeine,theobromine,theophylline )

Aroma forming substances

Carbohydrates & associated compounds.

Vitamins

Inorganic constituents

The polyphenols: The most important and characteristics component of tealeaf is the polyphenols which is located in cell sap undergo a series of chemical changes when the leaf is disintegrated during tea manufacture. Polyphenols occurring in teas are derivatives of gallicacid and catechin. The best-known Gallic acid derivatives are the tannins, which impart colour, body and taste to the brew. The catechins in the tea leaf are:

1.Simple catechins

2.Gallocatechins

3. Gallates of catechins and gallocatechins. The six catechins that are recognized are:

(a) Epigallocatechin-3-gallate

(b) Epigallocatechin

(c) Epicatechin-3-gallate

(d) Epicatechin

(e) Gallocatechin and

(f) Catechin

The catechins are water soluble, colourless substances with an astringement taste.

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It has been known for many years that fermentation of tea involves the oxidation of catechins to form brown coloured pigments. After some difficulties, it was shown that the pigments were of two types, which subsequently became known as the theaflavins and thearubigins.

Pigments/Flavonoids: The green colour, chlorophyll of tealeaf enters into the chemical reactions of tea manufacture and is decomposed in the process of fermentation (pheophytin). Tealeaf also contains red and yellow pigments derived from anthocyanins and flavones. The yellow pigment is changed into anthocyanins(red).

Proteins and amino acids: Green leaf contains about 4.5 to 5% of nitrogen and three-fourth of this is proteins and amino acids. The main enzymes found in tea leaf are invertase, amylase, betaglucosidase & pectinase. The primary oxidative enzymes are O-diphenoloxidase and peroxidase. Other enzymes present in tea leaf are pectinmethylesterase, alcoholdehydrogenase,transaminase,peptidase,reductase etc. the enzymes are responsible for breaking down the polyphenols to different compounds in presence of oxygen. Amino acids are responsible for the development of flavour. Catechin-aminoacids reaction in presence of O-diphenoloxidase or at high temperature results in the formation of aldehydes, which are responsible for tea aroma. The amino acids that are found in black tea are aspartic acid, leucine, asparagine, tyrosine, arginine, histidine, lysine, glutamic acid, phenylalanine, valine, alanine and serine. Cartwright et al. (1954) reported that L-theanine (5- N- ethylglutamine) is an amino acid unique to tea where as other acids found in tea are common to most plants.

Alkaloids (caffeine,theobromine & theophylline): The most valuable component of tea is alkaloids i.e. caffeine, theobromine and theophylline. Caffeine is a purine derivative, which is 1, 3, 7-tri- methyl xanthine. Caffeine content in black tea is around 3 – 4% of dry weight. It has stimulating property and removes mental fatigue. The contribution of caffeine to the infusion is the briskness and creamy property resulting from the complex formed by caffeine with polyphenols. Briskness is a taste and sensation while creaming is the turbidity that develops from a good cup of tea when cooled.Caffeine and tannin make a complex- caffeine tannate, which gives pleasant taste and aroma, although separately each has a bitter taste. Caffeine is associated with theaflavin, which imparts briskness to the tea infusion. Caffeine –tannin complex gives tea cream when cooled which makes tea infusion turbid.

Aroma forming substances:

A large number of volatile compounds collectively referred to as the aroma complex have been identified in tea. Those thought to be of greatest importance are acids,alcohols,aldehydes,esters,hydrocarbons, lactones,phenols,nitrogenous compounds,sulphur compounds and miscellaneous oxygen compounds. On steam distillation, black tea gives essential oil. The characteristics aroma and flavour of tea is due to the essential oil.

Carbohydrates & associated compounds:

Sugars (0.73-1.41%) and starch (0.82-2.96) are found in tealeaf. The presence of glucose, fructose, sucrose, arabinose and ribose is in small quantities. Pectins are present in quite large amounts in tea flush. It is highest in the stalk(7.6%), 2nd in the 1st leaf(6.1%) and lower in the bud and older leaves. It breaks down in the course of manufacture to form pectic acid and methyl alcohol.

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Organic acids

Citric, tartaric, malic, oxalic, fumaric and succinic acids were detected in Assam leaf. Role of organic acids towards the biochemical influence on the quality of black tea is not yet reported.

Vitamins:

There is presence of vitamins B, C, & P. Ascorbic acid is oxidized during fermentation.

Inorganic constituents: the inorganic constituents are found mainly as salts in the cell sap. These are: potassium(1.76%),calcium(0.1%),phosphorus(0.32%),magnesium(0.22%), iron(0.15%),manganese(0.17%),sulphur(0.088%),aluminium(0.069%), sodium(0.03%), silicon(0.024%), zinc(0.003%) and copper(0.002%). The total ash content in green leaf varies from 4.5-5%.

Chemical composition of fresh tea leaves.

The average chemical composition of fresh tea leaf is polyohenols 22.2%, protein 17.2%, caffeine 4.3%, crude fibre 27%, starch 0.5% and ash 5.6%.

Table 1 The average chemical composition of tender shoots is as follows:

Main substances chemicals total % of dry leaf % of water soluble part

Cell wall Cellulose fibre

Hemicellulose 24.0 0.0

Legnin, pectin 6.5 2.3

Vacuole polyphenols 22.0 22.0

Caffeine 4.0 4.0

Amino acid 7.0 7.0

Sugar 3.0 3.0

Organic acid 3.0 3.0

Ash 5.0 4.0

Protoplasm Protein 17.0 0.0

Fat 8.0 0.0

Starch 0.5 0.0

Total 100.0 45.3

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Table 2 Analytical figure for black tea

Constituents % dry weight (except m.c.)

Moisture 3.9-9.5

Total ash 4.9-6.5

Water-soluble ash 3.0-4.2

Acid insoluble ash 0.1-0.4

Alkalinity of water-soluble ash (as K2O) 1.2-2.0

Extractives 30-50

Caffeine 1.9-3.6

Tannin 7.3-15.1

Total Nitrogen 5.0-6.2

Crude Fibre 14-18

Ether extract 10-11

Table 3 Chemical standard for Indian tea

Chemical constituents Present standard Standard recommended

Moisture - Max 8%

Total ash 5.0-8.0 4.8-7.0

Water-soluble ash Min 40% Min 50%

Acid insoluble ash Max 1.0% Max 0.6%

Alkalinity of soluble ash 1.3-2.0% 1.4-2.0%

Extractive Min 35.0% Min 38%

Crude fiber Max 15.0% Max 12.0%

Caffeine - Min 2.5%

Tannin - 6.0-12.0%

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Table 4 Chemical specification of the ISO 3720 for black tea

Characteristics Requirements

Water extract (m\m)% min 32

Total ash (m\m) max 8

min 4

Water soluble ash (as% of total ash) 45

Alkalinity of soluble ash (as K2O) min 1

Max 3

Acid insoluble ash %(m\m) max 1

Crude fiber% (m\m) max 16.5

Table 5 Nepal standard for black tea

Characteristics Requirements

Water extract min 32%

Total ash 5.5-8%

Water soluble ash (as% of total ash) min 40%

Alkalinity of soluble ash (as K2O) 1.0-2.0%

Acid insoluble ash max 1.0%

Caffeine min 2.3%

Crude Fiber max 15.1%

Manufacture of tea

Based on the degree of fermentation, tea has been classified into three groups:

• Unfermented tea : Green tea

• Semi-fermented tea : Oolong and Pouchong tea

• Fully -fermented tea : Black tea

Black tea is fully fermented tea. The main steps of black tea manufacturing are: Plucking, withering, rolling, fermentation, drying, grading &packaging.

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In green tea manufacturing, the fermentation is prevented by inactivating the enzymes present in the flush. The manufacturing steps of green tea are plucking, steaming/panning, primary rolling and firing, rolling, secondary drying, final rolling, final drying, grading& packaging.

Partially fermented tea having flowery characteristics prepared from selected clones is termed as semi-fermented tea. They are of two types, namely Oolong tea and Pouchang tea. The basic manufacturing steps are plucking, outdoor withering, indoor withering, panfiring, rolling, final drying and grading.

Technology of black tea manufacturing

Tea production technology is essentially a biochemical technology, since the transformation of the green tea leaf, which has bitter taste, and grassy odour into an aromatic and tasty manufactured tea is based on biochemical process. The central theme of black tea manufacturing is fermentation. The process, however, does not entail anaerobic or bacterial fermentation. The primary reaction is the oxidation and condensation of tea catechins or tannins. In black tea manufacturing, the object is to condition green leaf for fermentation, attain optimum fermentation and then arrest it. This is achieved by rupturing the leaf cells to release the enzyme and to expose them to oxygen. As soon as optimum fermentation is achieved, the leaf mass is passed through hot air which destroys the enzymes and thus arrests the process. Fermentation results in qualitative and quantitative changes in tea leaf constituents contributing to the formation of new taste and aroma products responsible for the character of manufactured black tea. There are three types of black tea manufacturing processes. They are (1) the orthodox or traditional process (2) CTC (crush,tear and curl) process (3) Legg- cut process.

Processing steps

The various processing steps in the manufacture of black tea are plucking, transportation, withering, rolling, fermentation, drying, grading and packaging.

Plucking: Plucking is one of the most vital operations in the production of tea. Plucking two or less leaves and a bud is known as fine while plucking three or less leaves and a bud is known as coarse. The finest quality of tea comes from the bud, next in quality is provided by the partly opened leaf next below it and lowest in quality will be the leaves next below which are obviously coarser. Orthodox process requires fine plucking.

Transportation : Withering commences as soon as the tea is plucked, but is uncontrolled until the tea reaches the factory. It is therefore, important that the plucked leaf should reach the factory as quickly as possible and provision of efficient transport is an important aspect of plantation management. It is also important to minimize damage to the leaf.

Withering: Withering is the first stage, in which the plucked leaf is spread on vast trays or racks, and left to wither in air temperatures of 25-30° C (77-86° F) for a period of 10-16 hours, depending on the wetness of the leaf. During withering, leaves lose moisture and as a result changes occur in the permeability of the of the cell membranes. This preconditions the leaf for the subsequent maceration and fermentation stages and is known as the physical wither. At the same time a number of biochemical changes occur-the chemical wither. During withering, it is necessary that air should circulate as freely as possible around the leaf. This is usually achieved by use of withering trough, a long, low, narrow rectangular box fitted with a perforated floor

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through which a fan blows air upward through a shallow bed of leaves. An air heater may be fitted, but it is important to avoid over-heating the leaf and the leaf temperature is usually maintained close to ambient. Withering times of 12-16 h are most common, although some factories operate on a 24 h withering cycle.

Objectives

*Moisture reduction from about 78% to about 55% to make maceration easier.

*To destroy the semi permeable properties of the cell membrane with out causing break down of tissue.

*To prepare the leaf for rolling by making the leaf tissue flaccid and permeable to the juices.

*To increase enzyme activity and soluble amino acid.

Rolling/ Leaf disruption

Leaf disruption is a physical process, which may be achieved in a number of ways. The basic function is a reduction in the size of the leaf material and some degree of cell disruption, which exposes new material to air during the subsequent fermentation process. The withered leaves are rolled to break upon the cells and release the juice and enzymes and to twist or curl the leaf. Rolling is achieved by rolling the leaf in a machine for one or two hours as if between the plams of two hands. It induce fermentation.

Rolling machine

The orthodox roller is a batch machine, which has been used for many years. A batch of leaf is loaded into a cylindrical hopper, positioned above a circular table, bearing a series of ridges, or battens, on its upper surface. Downwards pressure is placed on the cylinder of leaf in the hopper, forcing the leaf at the lower end into contact with the table. The table and hopper move eccentrically to each other, brushing, rolling and disrupting the leaves. The degree of disruption can be carried by varying the downward pressure on the cylinder. The orthodox roller requires a fairly dry leaf with a moisture content of ca.60% and the output contains a relatively high proportion of large particles. These can be recycled back to the roller or, alternatively, the orthodox roller may be used in combination with a different type of machine.

The rotorvane machine was developed in an attempt to reproduce the physical action of the orthodox roller on a continuous basis. The rotorvane machine consists of a horizontally mounted rotor, fitted with pairs of opposed vanes, surrounded by a cylindrical outer jacket, the inner surface of which is ribbed. Leaves enter the rotorvane machine from a hopper and are propelled to the discharge end by the rotor. Disruption of the leaves occurs by rubbing against the ribs of the outer casing, an adjustable choke at the discharge end allowing pressure within the machine to be varied. The temperature of the leaf rises during passage through the rotorvanes and there must be provision for cooling immediately after disruption. The rotorvanes have been replaced by the more modern Boruah continuous roller machine. This machine has a conical rotor wgicg oscillates through 180o. The rotor is placed in a stationary outer chamber fitted with ridges and battens to act as rubbing surface. The CTC machine is very widely used and produced small particles, popular for use in tea bags. Detailed design varies, but the machine basically consists

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of one or more pairs of contra-rotating rollers. The surface of the rollers are machined in a pattern designed to give a tearing and cutting action and this is aided by a speed differential, usually 10:1, between the rollers. CTC machines produced a high value product, but require skilled maintenance. The machine is able to handle leaves with a relatively wide range of moisture contents, but operates most effectively at 68-70%. Cooling air is supplied to prevent over-heating of the leaves.

The Lawrie tea processor (LTP machine), is one of the simplest designs and consists of hinged knives and beaters mounted on a rotor which spins within a circular casing. Cutting and crushing takes place as the leaves move from a hopper through the machine to the discharge end. The LPT machine is ineffective at leaf moisture levels in excess of ca. 71% and over-heating can be a serious problem.

Fermentation

The most important step in black tea manufacture is fermentation. The biochemical change developed during the withering stage proceed at the most rapid rate during fermentation. These changes result in quantitative and qualitative changes in tealeaf constituents contributing to the formation of new taste and aroma products responsible for the character of manufactured black tea. Fermentation starts during rolling. In the anatomical structure of tea cell, vacuole contains a solution of water-soluble substances like catechins, caffeine, amino acid, sugar etc.In the fluid of cell there are plastids containing oxidative enzymes. During rolling the thin membranous wall around the vacuole, which keeps the catechins away from the enzyme, ruptures resulting in the intermixing of the catechins with enzymes. The mass of rolled leaf is spread out thinly on suitable plate form and allowed to ferment for 40 min to 3 h at temperature between 210C-270C and 85% R.H. During this process, the enzymes bring about the oxidation of the various polyphenols present in the juices resulting in the change of colour from green to reddish copper. The enzyme oxidase brings the oxidation of polyphenolic bodies to orthoquinones. It is generally assured that subsequently the orthoquinones are condensed by the process known as demerization to bisflavonols and these in turn rapidly condense to theaflavins which are yellow bodies. An additional oxidation transfer these theaflavins to thearubigins which are red and brown bodies. Finally some TRs are precipitated by leaf proteins to form complex polyphenols. The overall reaction is summarized as below.

Polyphenolic bodies enzyme orthoquinones demerization bisflavonols

(Catechin group) (Highly unstable)

Condensation

precipitation Condensation

Complex polyphenols Thearubigins(TR)

With protein (Reddish brown) Theaflavins(TF) (Yellow colour)

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TF is responsible for briskness and TR is responsible for depth(colour). As the period of fermentation is prolonged the proportion of thearubigins increases.

The time of fermentation is calculated from the time of rolling starts.

Drying /Firing

When the fermentation has proceeded to the desired degree, further change is arrested by drying or firing. This comprises the passing of fermented leaves through a chamber with perforated moving trays in which hot air of 930C - 1210C is circulated which drops to about 49 0C near exit. The time required is about 14 to 16 min and dry product contains 3-4% moisture. Drying stops the fermentation process by inactivating the enzymes, causes some caremelization resulting characteristics colour, and a number of chemical changes take place among the chemical substances like pectin, amino acid, sugar and organic acids.

pectase

Pectin Pectic acid + Methyl alcohol

>120 0F

Methyl alcohol evaporates just after formation. But pectic acid is the most important substance for keeping quality of tea andappearance. The pectic acid forms a waxy layer and tea particle gives a sort of fine appearance called bloom and fine bloom always earns a high price in the market. This chemical change leads to a better keeping quality of tea.

Grading Teas are graded by the size of the processed leaf. Traditional operations result in larger leafy grades and smaller broken grades. The leafy grades are flowery pekoe (FP), orange pekoe (OP), pekoe (P), pekoe souchong (PS), and souchong (S). The broken grades are broken orange pekoe (BOP), broken pekoe (BP), BOP fanning, fannings, and dust. Broken grades usually have substantial contributions from the more tender shoots, while leafy grades come mainly from the tougher and mature leaves. In modern commercial grading, 95 to 100 percent of production belongs to broken grades, whereas earlier a substantial quantity of leafy grades was produced. This shift has been caused by an increased demand for teas of smaller particle size, which produce a quick, strong brew.

Tea leaving the dryer is in a relatively crude state and consists of a mixture of different sized leaf particles together with a quantity of stalk and fiber. The tea is sorted into portion by size, during passage through a vertical stack of vibrating mesh screens. Stalk and fiber is removed by

Fermentation time(hrs) 1 2 3 4 5

TF percent 1.61 1.46 1.34 1.27 1.17

TR percent 13.0 16.6 16.6 16.7 17.1

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electrostatic attraction during passage close to electrically charged rollers. The particle size in each portion, the grade, is determined by the size of the mesh. There is, however, no internationally recognized nomenclature, although the grade names do give an indication of the method of processing and of leaf particle size.

The humidity is the cleaning and sorting room should be as low as possible both to minimize moisture pickup the tea and to ensure effective operation of the electrostatic equipment. In areas of high humidity, localized heating in the vicinity of the electrically charged rollers is required.

Packaging

Tea is very hygroscopic and its ability to remain in good condition is highly dependent on its moisture content. Therefore, the main technical requirement for packaging of teas at any stage is the provision of an adequate moisture barrier.

Teas are packed in airtight containers in order to prevent absorption of moisture, which is the principal cause of loss of flavour during storage. Packing chests are usually constructed of plywood, lined with aluminum foil and paper, and sealed with the same material. Also used are corrugated cardboard boxes lined with aluminum foil and paper or paper sacks lined with plastic.

Blended teas are sold to consumers as loose tea, which is packed in corrugated paper cartons lined with aluminum foil, in metal tins, and in fancy packs such as metallized plastic sachets, or they are sold in tea bags made of special porous paper. Tea bags are mainly packed with broken-grade teas.

Average chemical composition of Orthodox and CTC teas made from Assam clone.

Composition Orthodox teas CTC teas

Water soluble solids % 39.52 41.12

Theaflavins % 0.59 1.30

Thearubigin % 6.5 18.00

Total Lipid 3.11 3.68

Carotenoids (ľg/g) 215 176

Flavour volatilesd 18.40 8.20

Total fibre % 19.35 18.93

Crude fibre% 11.70 11.12

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Biochemical compounds responsible for colour

Compounds Colour

Theaflavins Yellowish brown

Thearubigins Reddish brown

Flavonol glycosides Light yellow

Pheophorbide Brownish

Pheophytin Blackish

Carotene Yellow

Biochemical compounds responsible for taste

Compounds Taste

Polyphenol Astringent

Amino acids Brothy

Caffeine Bitter

Theaflavins Astringent

Thearubigin Ashy and slight astringent

Chlorophyll a mg/g 1.38 0.48

Chlorophyll b mg/g 0.77 0.58

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Biochemical compounds responsible for flavour

Compounds Flavour

Linalool, Linalool oxide Sweet

Geraniol, Phenylacetaldehyde Floral

Nerolidol, Benzaldehyde, Methyl salicylate, Phenyl ethanol Fruity

Trans-2-Hexenal, n-Hexanal, Cis-3-Hexenol, Grassy, b-Ionone Fresh flavour

Principal Components of Black Tea Beverage

Components Concentration (g/100g)

Catechins 3

Theaflavins 3

Thearubigins 12

Flavanols 6

Phenolic acids and Depsides 10

Amino acids 13

Methylxanthines 8

Carbohydrates 10

Protein 0.8

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Chemical Composition of Fresh Tea Shoot

Compounds % Dry weight Contribution

Total Polyphenols 25 - 30 Astringency

Flavanols

(-) Epigallocatechin gallate 8 – 12

(-) Epicatechin gallate 3 – 6

(-) Epigallo catechin 3 – 6

(-) Epicatechin 1 – 3

(+) Catechin 1 – 2

(+) Gallocatechin 3 – 4

Flavonols and flavonol glycosides 3 – 4

Leuco anthocyanins 2 – 3

Polyphenolic acids and depsides 3 – 4

Caffeine 3 - 4 Briskness

Theobromine 0.2

Theophylline 0.5

Amino acids 4 – 5 Brothyness

Organic acids 0.5 – 0.6

Monosaccharides 4 – 5

Polysaccharides 14 - 22

Cellulose and Hemicellulose 4 – 7

Pectins 5 – 6

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Lignin 5 – 6

Protein 14 – 17

Lipids 3 – 5

Chlorophylls and other pigments 0.5 - 0.6 Colour and Appearance

Ash (minerals) 5 – 6

Volatiles 0.01 – 0.02 Aroma

Average chemical composition of Orthodox and CTC teas made from Assam clones

Composition Orthodox teas CTC teas

Water soluble solids % 39.52 41.12

Theaflavins % 0.59 1.30

Thearubigin % 6.5 18.00

Total Lipid 3.11 3.68

Carotenoids (ľg/g) 215 176

Flavour volatilesd 18.40 8.20

Total fibr % 19.35 18.93

Crude fibre% 11.70 11.12

Chlorophyll a mg/g 1.38 0.48

Chlorophyll b mg/g 0.77 0.58

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Biochemical compounds responsible for flavour

Compounds Flavour

Linalool, Linalool oxide Sweet

Geraniol, Phenylacetaldehyde Floral

Nerolidol, Benzaldehyde, Methyl salicylate, Phenyl ethanol Fruity

Trans-2-Hexenal, n-Hexanal, Cis-3-Hexenol, Grassy, b-Ionone Fresh flavor

Principal Components of Black Tea Beverage

Components Concentration (g/100g)

Catechins 3

Theaflavins 3

Thearubigins 12

Flavanols 6

Phenolic acids and Depsides 10

Amino acids 13

Methylxanthines 8

Carbohydrates 10

Protein 0.8

Mineral matter 8

Volatiles 0.05

(Components measured in wt % of extract solids)

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The components

Caffeine

Caffeine is a purine derivative, which is 1,3,7-tri- methyl xanthine. Caffeine content in black tea is around 3 – 4% of dry weight. It has stimulating property and removes mental fatigue. The contribution of caffeine to the infusion is the briskness and creamy property resulting from the complex formed by caffeine with polyphenols. Briskness is a taste and sensation while creaming is the turbidity that develops from a good cup of tea when cooled.

Tea fibre

The leaf cell wall, containing cellulostic materials surrounded by hemi-cellulose and a lignin seal, prevents the penetration of hydrolyzing enzymes. The reduced succulence in the matured shoot is believed to be due to structural bonding between phenolic components of lignin, polysaccharides and cutin of cell wall.

Carbohydrates

The free sugars found in tea shoot are glucose, fructose, sucrose, raffinose and stachyose. Maltose in Assam variety and rhamnose in china variety appeared special. Pectic substances contain galactose, arabinose, galacturonic acid, rhamnose and ribose. Free sugars are responsible for the synthesis of catechins in tea shoot, formation of heterocyclic flavour compounds during processing of black tea and contributing towards water-soluble solids in tea liquor. Cellulose, hemi-cellulose, pectins and lignins are responsible for the formation of crude fibre content in black tea.

Tracer studies using 14C-glucose in detached tea shoot showed that glucose was one of the precursors of polyphenols in tea. Except theanine all amino acids present in tea shoot were biosynthesized using 14C-glucose, 14C-sodiam carbonate and 14C-sodium propionate. Theanine was mainly synthesized in the root and translocated to the shoot.

Amino acids

Aspartic, glutamic, serine, glutamine, tyrosine, valine, phenylalanine, leucine, isoleucine and theanine (5-N-ethylglutamine) were found to be the principal amino acids present in tea leaf. Theanine alone contributed around 60% of total amino acid content. Asparagine was formed during withering. The amino acids play an important role in the development of tea aroma during the processing of black tea.

Volatile Carbonyl Compounds formed from the amino acids during processing: Glycine —› formaldehyde Alanine —› acetaldehyde Valine —› isobutyraldehyde Leucine —› isovaleraldehyde Isoleucine —› 2-methylbutanol Methionine —› methional Phenyl alanine —› phenylacetaldehyde

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Lipids and fatty acids

The neutral, glyco and phospholipid contents and their fatty acid composition varied in Assam, China and Cambod varieties and also during different stages of black tea manufacture. Total lipid contents(%) and total fatty acids (ľg/g) at different stages i.e. green leaf, withered leaf, rolled leaf, fermented leaf and black teas are about 6.5, 5.7, 4.5, 4.3 and 2.8 and 9.8, 8.4, 6.6, 4.8 and 3.7 respecttively. The major fatty acids available in tea are linolenic, linoleic, oleic and palmitic.

Carotenoids

The four major carotenoids, ß-carotene, lutein, violaxanthine and neoxanthine were estimated spectroscopically in four different Tocklai released clones, namely, TV-1 (China hybrid), TV-2 (Assam Betjan variety), TV-9 (Assam-Cambod variety) and TV-17 (China hybrid). The quantitative changes of these carotenoids in different stages of black tea manufacture were also studied in TV-2 (less flavoury) and TV-17 (flavoury) clones against TV-1 as standard. Comparative study showed that TV-2 contained the least amount of these carotenoids whereas TV-9 and TV-17 contained higher amounts. All these carotenoids were found to decrease appreciably during black tea manufacture. The decrease was found to be higher in curling, tearing and crushing method than in the conventional orthodox method of tea manufacture. The changes of two of these carotenoids viz. -carotene and lutein were not significant statistically during withering but were highly significant during fermentation. However, the reverse was true for violoaxanthine where as the neoxanthine shows significant changes in both of these stages. The vitamin A value was calculated from the residual -carotene amount, pro-vitamin A, in black tea.

Anthocyanidins

Delphenidin and cyanidin were the major anthocyanidins present in tea leaf. Anthocyanin contents were higher in tea shoots from pruned than those of unpruned bushes. Role of anthocyanins on the quality of black tea however, has not been found to be significant.

Organic acids

Citric, tartaric, malic, oxalic, fumaric and succinic acids were detected in Assam leaf. Role of organic acids towards the biochemical influence on the quality of black tea is not yet reported.

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Coffee processing technology

Coffee is an evergreen shrub or small tree. The coffee plant is a woody perennial evergreen dicotyledon. Coffee flowers are white and sweet smelling, producing green berries, which turn red when ripe. The ripe coffee fruits are called cherries or grapes. The coffee–cherry contains a mucilaginous pulp with two greenish grey seeds or beans, each covered by a thin membrane, the silver skin, and both are enclosed in a common husk-like membrane or parchment. Sometimes a single bean fills the berry instead of two and the seed is called a pea berry since it is like a pea. The beans grow in pairs of seeds in cherries. The ripe berries are picked for processing.

Coffee History

According to a coffee history legend, an Arabian shepherd named Kaldi found his goats dancing joyously around a dark green leafed shrub with bright red cherries in the southern tip of the Arabian Peninsula. Kaldi soon determined that it was the bright red cherries on the shrub that were causing the peculiar euphoria and after trying the cherries himself, he learned of their powerful effect. The stimulating effect was then exploited by monks at a local monastery to stay awake during extended hours of prayer and distributed to other monasteries around the world. Coffee was born. Despite the appeal of such a legend, recent botanical evidence suggests a different coffee bean origin. This evidence indicates that the history of the coffee bean beagan on the plateaus of central Ethiopia and somehow must have been brought to Yemen where it was cultivated since the 6th century. Upon introduction of the first coffee houses in Cairo and Mecca coffee became a passion rather than just a stimulant.

Geographically coffee grows between the Tropic of cancer and the Tropic of Capricorn (torrid zone). Outside this area coffee cannot survive when there is opportunity for frost. Higher the altitude, the quality of coffee will be better. The limiting factor is the frost danger zone. Most of the coffee is grown in volcanic soils.Temperature of 20±3°C and annual rainfall between 1500 and 2000 mm are ideal for coffee. Average coffee yield is around 500 kg / ha

The different species of coffee are given below: Coffee arabica – Largest and best quality of coffee beans Coffee robusta – Yields beans of lower quality Coffee liberica – Beans are of still lower quality.

The Difference Between Arabica and Robusta Coffee Beans

While there are several different coffee species, two main species of coffee are cultivated today. Coffea arabica, known as Arabica coffee, accounts for 75-80 percent of the world's production. Coffea canephora, known as Robusta coffee, accounts for about 20 percent and differs from the Arabica coffees in terms of taste. While Robusta coffee beans are more robust than the Arabica plants, but produces an inferior tasting beverage with a higher caffeine content. Both the Robusta and Arabica coffee plant can grow to heights of 10 meters if not pruned, but producing countries will maintain the coffee plant at a height reasonable for easy harvesting.

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Coffee Plant Growth and Development

Three to four years after the coffee is planted, sweetly smelling flowers grow in clusters in the axils of the coffee leaves. Fruit is produced only in the new tissue. The Coffea Arabica coffee plant is self-pollinating, whereas the Robusta coffee plant depends on cross pollination. About 6-8 weeks after each coffee flower is fertilized, cell division occurs and the coffee fruit remains as a pin head for a period that is dependent upon the climate. The ovaries will then develop into drupes in a rapid growth period that takes about 15 weeks after flowering. During this time the integument takes on the shape of the final coffee bean. After the rapid growth period the integument and parchment are fully grown and will not increase in size. The endosperm remains small until about 12 weeks after flowering. At this time it will suppress, consume, and replace the integument. The remnants of the integument are what make up the silverskin. The endosperm will have completely filled the cavity made by the integument nineteen weeks after flowing. The endosperm is now white and moist, but will gain dry matter during the next several months. During this time the endosperm attracts more than seventy percent of the total photsynthesates produced by the tree. The mesocarps will expand to form the sweet pulp that surrounds the coffee bean. The coffee cherry will change color from green to red about thirty to thirty-five weeks after flowing.

Coffee is a high value cash crop with environmental importance and is being popular among Nepalese people since last few decades It has been spreading in over 39 districts of the middle hill region of Nepal.Coffee can be commercially produced in many parts of the country. However, there is great potentiality in mid hills region for organic coffee production as it has got suitable climate, topography, Soil, relative humidity, Temperature and Rainfall for Arabica coffee. Some Districts like Gulmi, Palpa, Argakhanchi, Lalitpur,Tanahu, Kavre, Sindhupalchowk, Lamjung, Kaski, Gorkha, Syangja, Parbat, Baglung are successfully growing and producing Coffee beans and is increasing gradually. This will certainly help in diversifying process and will increase the income of the farmers as well as other individuals involved in coffee processing and marketing enterprise. Nepal is Exporting Coffee bean mostly in Japan,America and European countries.This has been extended to other parts of the word

Red Cherry to Green Bean

What we call a coffee bean is actually the seeds of a cherry-like fruit. Coffee trees produce berries, called coffee cherries, that turn bright red when they are ripe and ready to pick. The fruit is found in clusters along the branches of the tree. The skin of a coffee cherry (the exocarp) is thick and bitter. However, the fruit beneath it (themesocarp) is intensely sweet and has the texture of a grape. Next comes the parenchyma, a slimy, honey-like layer, which helps protect the beans. The beans themselves are covered by a parchment-like envelope called the endocarp. This

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protects the two, bluish-green coffee beans, which are covered by yet another membrane, called the spermoderm or silver skin.

There is usually one coffee harvest per year. The time varies according to geographic zone, but generally, north of the Equator, harvest takes place between September and March, and south of the equator between April and May. Coffee is generally harvested by hand, either by stripping all of the cherries off the branch at one time or by selective picking. The latter is more expensive and is only used for arabica beans. Once picked, the coffee cherries must be processed immediately

About 12-20 kg of export ready coffee will be produced from every 100 kg of coffee cherries harvested.

Right after picking, it's time for processing. This is done in one of two ways:

Dry method - By the simplest and cheapest method, the harvested cherries are spread out to dry in sunlight. They are periodically raked and turned for seven to 10 days, until their moisture content has fallen to 11 percent. The outer shell of the cherries turns brown and the beans rattle around inside.

Wet method - The main difference between the wet and dry method is that in the wet method, the pulp of the coffee cherry is removed from the beans within 24 hours of harvesting. A pulping machine washes away the skin and pulp. The beans are put in fermentation tanks for 12 to 48 hours. Natural enzymes loosen the slimy parenchyma from the parchment covering. The beans are then dried, either by the sun or by mechanical method. Once the beans are dried, all of the layers are removed from the beans (this process is called hulling). Occasionally, beans may be polished in a machine designed to remove that last little bit of silver skin. Beans are then graded and sorted, first by size, then by density. Beans are either sorted by hand as they pass by on a conveyer belt or by an air jet that separates lighter (inferior) beans from heavier ones.

Coffee is shipped unroasted. This is called green coffee. It is stored in bags made of jute or sisal, or shipped in huge plastic-lined freight containers. About 7-million tons of green coffee is shipped worldwide each year.

Coffee processing methods

Processing of coffee consists of removal of the skin, pulp, parchment and silver skin. The quality of the final product depends upon the method of processing.There are two main methods used in coffee processing viz., washed (wet) process and natural (dry) process. In the wet process, the ripe fruit is squeezed in a pulping machine which removes most of the soft outer pulp. The product is called washed coffee. The washed coffee is then dried to 12 per cent moisture content and then yellow parchment layer is removed in a hulling machine and the finished green coffee results. In the natural method, the fruit is allowed to remain on the tree after the fully ripe stage and is partially dried before harvesting. After harvesting it is dried and dehulled.

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Steps in coffee processing

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(i) Storage of harvested coffee

In the case of washed coffee, ripe cherries are dumped into a tank partially filled with water. The floats, which are considered inferior, are removed.

(ii) Classification of coffee cherries

Classifying systems of coffee employ the principles of floatation and screen separation by size. Systems of this type require large amounts of water. The cherries are drawn from the bottom of storage tank to a stone and dirt remover. The berries that sink with stones and dirt pass down the U-shaped chamber. Stones and dirt collect at the bottom being heavier than coffee. The floats by-pass the U-shaped trap. Separate canals lead the floats and sinkers into rotating screens.

(iii) Pulping

The pulping operation has two steps: first, the fruit is squeezed between the roughened surface of either a rotating cylinder or a disk and a stationary member with a smooth slotted surface. The squeezing action detaches skin and flesh i.e. the pulp from the screen. In the second step, the seeds are separated from the pulp by means of a plate fixed at right angles to the cylinder or disk with a precisely regulated clearance of 1.5 mm. The seed is then taken to a stream of water for next operation.

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(iv) Removal of mucilage

The freshly pulped coffee seeds are covered with a slippery mucilaginous layer. The presence of this layer delays drying and handling will be hard. The mucilage can be removed by:

a) Natural fermentation, b) Fermentation with enzymes, c) Chemical methods, d) Warm water and e) Pulping f) Washing

(a) Natural fermentation

It is used for 90-95 % of present washed coffee production. The pulped coffee is placed in tanks, water is drained and the coffee is held until the mucilage is dispersible. When the digestion is complete coffee beans are washed. The time required for digestion varies from 6 to 72 hours depending on temperature and thickness of mucilage. For a typical, average coffee plantation at altitudes between 600 to 1200 m, the natural fermentation time is 24 hours.

Chemistry of Fermentation

The coffee beans covered in the slippery mucilage can be sent to the patios to dry as pulped natural coffees or can be sent to coffee fermentation tanks. The coffee fermentation tanks are used to remove the mucilage before drying. The pulped coffee beans are put into cement tanks with water and are allowed to ferment for 16-36 hours. On the way to the fermentation tanks, another density separation can occur. The highest quality coffees are the densest and should be separated and fermented in a different tank.T he coffee fermentation time depends on a number of factors including the amount of coffee fermenting, water temperature, and humidity. The mucilage is made up of pectin materials including protopectin (33%), reducing sugars including glucose and fructose (30%), non-reducing sugars such as sucrose (20%), and cellulose and ash (17%) (Wrigley, 455). Protopectin is not water soluble and will hydrolyze to pectinic acid in the fermentation tanks (Wrigley, 455). Hydrolysis of the protopectin and degradation of the pectin by enzymes is the process that occurs to remove the mucilage during fermentation (Wrigley, 455). Currently, the best way of determining the end of coffee fermentation is to feel the coffee beans to determine if they are still encased in mucilage. If the coffee beans are fermented for 36-72 hours, stinker beans develop. Lactic, acetic, and propionic acids are produced in this process and are believed to prevent the traditional fermentation taste by inhibiting mold growth that regularly occurs during drying on a patio in humid conditions (Wrigley).

(b) Fermentation with enzymes

To accelerate digestion of mucilage, pectic enzymes containing pectase, pectinase etc. as active ingredients are added to reduce the digestion time to 8 hours, which improves quality.

(c) Chemical method

Sodium hydroxide solution of 3-5 % concentration or 6-8 % sodium bicarbonate solution is used and the digestion time is varied between 30 minutes to 1 hour for removal of mucilage.

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(d) Warm water

Equal quantities of pulped coffee and water are mixed and heated to 50±3°C as quickly as possible. The warm water breaks down the mucilage gel and the coffee is washed after 3 min.

(e) Pulping Pulper is a machine accomplishing both pulping and mucilage removal in one operation. The machine consists of a rotating horizontal cylinder inside a fixed cylinder with ribbed surface. The inner cylinder make partial rotation of coffee bean and pressure is built up within the machine by an adjustable outlet. Water is fed in along with the coffee. Small slots are provided at the bottom for the escape of water, mucilage and pulp.

(v) Washing

Washing is done with the help of washer, which is a low pressure, low power machine which removes mucilage by attrition. It is a trough vibrating longitudinally and contains fixed and moving baffles. The coffee beans are rubbed against each other and on the baffles and by the time the coffee has traveled from one end of the trough to the other end and the mucilage is rubbed off. In vertical type washer, a vertical steel cylinder is covered at top. A vertical shaft with arms is rotated at 300 rev / min. Baffles are attached to the inside of stationery cylinder. The pulped coffee and water are fed at the bottom. The mucilage is removed by the time the coffee overflows from top outlet.

The maximum loss of solids during fermentation is 4.8 % in 24 hours which is the average time required for natural fermentation. The quick removal of mucilage using washers will avoid this weight loss.

(vi) Drying of green coffee beans (a) Sun drying

The berries are sun dried by spreading them out on drying floors and the coverings are removed by hulling. The thickness of layer in natural sun drying is 50-100 mm and the coffee is stirred at frequent intervals. The beans are later cured in curing sheds. The product obtained is known in trade as cherry or native coffee.

(b) Mechanical drying

Mechanical drier consists of horizontal tunnel, the top of which is enclosed by trays with bottoms of wire screen or perforated metal. Wet coffee is placed in the trays and heated air under sufficient pressure is passed through the coffee. The source of heat may be wood, coal, oil, hot air or steam of dried coffee pulp.

(vii) Dehulling

Hulling machine removes the dried skin, pulp and parchment from the dried cherry. The hulling machine consists of iron screw with helical pitch increasing towards the discharge end. Hulling is achieved by creating friction among the beans. The broken parts of the parchment along with dust fall through a perforated steel plate at the bottom of the screw by means of suction air to a cyclone separator. An average hulling loss for arabica parchmen coffee is 20 %.

(viii) Roasting

Coffee is then taken to the roasting plant. Large size particles are removed in a rotary screen and light materials are removed by air. In small plants, green coffee is blended within the roasting cylinder. In large plants, blending is done before the beans enter the cylinder. Raw or green coffee has no flavour or aroma and has an unpleasant taste. Roasting of green coffee affects the most important physical and chemical changes in the coffee because flavour

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is developed here. For use as a beverage, it is roasted, powdered and brewed and the aqueous extract used as a beverage with or without the addition of milk, sugar and other substances.During roasting many physical and chemical changes occur. The beans swell in size to almost double of their original size, the dull-green colour changes to brown and the characteristic coffee aroma develops. The beans lose their hard horny structure and become brittle, with the outer surface still smooth and firm.

During roasting, pressure develops in the beans and this appears to be necessary for the proper development of coffee flavour. The flavour is due to a mixture of numerous components rather than a definite chemical entity and is apparently produced during roasting. Some moisture is lost during roasting and carbon dioxide is produced in large quantity, some of it escapes and rest get absorbed within the texture of the roasted bean. Carbohydrates decompose, caramalize and perhaps in combination with other substances, contribute to the aroma of the beverage produced from the roasted beans. Fatty constituents are also affected and volatile fatty acids are driven off from the coffee bean. Complex fats and waxes are cracked to form simple ones. Proteins are hydrolyzed and give cleavage products. There is little change in the caffeine content of coffee during roasting.The flavour of roasted coffee, to a large extent, depends upon the manner and extent of roasting. The flavour and aroma of coffee are best when it is freshly roasted and deteriorate on standing. The staleness of coffee exposed to air is due to the oxidative changes that take place with certain coffee constituents.

Oxidative changes can be prevented by the presence of carbon dioxide in roasted coffee. On storage, carbon dioxide is lost and so are the flavour and aroma. Moisture also has a profound effect on the flavour of coffee. Coffee exposed to moisture loses all its flavour in a relatively short time.

(ix) Grinding

The roasted coffee is made into powder with the help of a Burr mill or Grinder and finally the coffee powder is packed in suitable packaging material for marketing and further consumption. Quality of CoffeeThe wet method gives better quality coffee with a bluish-green colour (green coffee). The green seeds are then graded and packed. Green coffee may be stored for prolonged periods with no adverse effects.

Each variety of coffee has its own flavour and other characteristics. Generally, marketed coffee is a blend of different varieties of coffee beans. The blends are controlled for flavour, aroma, colour and strength from the roasted bean.

Quality of Coffee

The wet method gives better quality coffee with a bluish-green colour (green coffee). The green seeds are then graded and packed. Green coffee may be stored for prolonged periods with no adverse effects. Each variety of coffee has its own flavour and other characteristics. Generally, marketed coffee is a blend of different varieties of coffee beans. The blends are controlled for flavour, aroma, colour and strength from the roasted bean.

Coffee grading

Coffee Grading and Green Coffee Beans Classification

Before any coffee is sold it is classified by the number of defects, screen size, and cup quality. The defect count is supposed to give a general idea of the quality of the cup. Two green coffee classification methods have been described here. The SCAA Green Coffee Classification Method is excellent for specialty green coffee beans,

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whereas the Brazilian/New York Green Coffee Classification Method is more precise, but also more time consuming.

SCAA Coffee Beans Classification (Specialty Coffee Association of America, SCAA)

The green coffee beans classification standard provided by the SCAA is an excellent method to compare coffee beans. It is superior over some systems in that it better accounts for the relationship between the defective coffee beans and the cup quality. However, it leaves out a few of the important coffee defects that can occur in coffee.

SCAA Method of Coffee Grading

Three-hundred grams of properly hulled coffee beans should be sorted using screens 14, 15, 16, 17, and 18. The coffee beans remaining in each screen is weighed and the percentage is recorded. Since classifying 300 grams of coffee is very time consuming, 100 grams of coffee is typically used. If you are dealing with a high grade coffee with only a few defects, use 300 grams. If the coffee is of a lower quality with many defects, 100 grams will often suffice in a correct classification as either Below Standard Grade or Off Grade. The coffees then must be roasted and cupped to evaluate cup characteristics.

Specialty Grade Green Coffee (1): Specialty green coffee beans have no more than 5 full defects in 300 grams of coffee. No primary defects are allowed. A maximum of 5% above or below screen size indicated is tolerated. Specialty coffee m ust possess at least one distinctive attribute in the body, flavor, aroma, or acidity. Must be free of faults and taints. No quakers are permitted. Moisture content is between 9-13%.

Premium Coffee Grade (2): Premium coffee must have no more than 8 full defects in 300 grams. Primary defects are permitted. A maximum of 5% above or below screen size indicated is tolerated. Must possess at least one distinctive attribute in the body, flavor, aroma, or acidity. Must be free of faults and may contain only 3 quakers. Moisture content is between 9-13%.

Exchange Coffee Grade (3): Exchange grade coffee must have no more than 9-23 full defects in 300 grams. It must be 50% by weight above screen size 15 with no more than 5% of screen size below 14. No cup faults are permitted and a maximum of 5 quakers are allowed. Moisture content is between 9-13%.

Below Standard Coffee Grade (4): 24-86 defects in 300 grams.

Off Grade Coffee (5): More than 86 defects in 300 grams.

Below is a chart for grading coffee beans. It is based on the primary defect and the number of defective coffee beans:

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Primary Defects

Primary Defect Number of occurrences equal to

one full defect.

Full Black 1

Full Sour 1

Pod/Cherry 1

Large Stones 2

Medium Stones 5

Large Sticks 2

Medium Sticks 5

Secondary Defects

Secondary Defects Number of occurrences equal to one full defect

Parchment 2-3

Hull/Husk 2-3

Broken/Chipped 5

Insect Damage 2-5

Partial Black 2-3

Partial Sour 2-3

Floater 5

Shell 5

Small Stones 1

Small sticks 1

Water Damage 2-5

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Classification of Green Coffee Beans: Brazil / New York Method Grading Coffee Beans in Brazil

In the Brazilian method 300 grams of coffee is classified. The number of coffee beans equivalent to one full defect is given below. For example, a set of three shells counts as one full defect. On the other hand, one large rock counts as five full defects. If a coffee bean has more than one defect, the highest defect is counted. For example, a bean that is black and damaged by insects counts as one full defect due to its black attribute. Generally, coffee beans without defects, of the same origin, and that are similar in size, color, and shape, are classified as specialty green coffee beans. The coffee beans classification table is split up into two, since Brazilian legislation allows a maximum of 1% of foreign defects. After counting the number of defects, use the third chart is used to classify the type and its point rating.

Intrinsic Defect Number Full Defects

Black bean 1 1

Sour (Including stinker beans)

1 1

Shells 3 1

Green 5 1

Broken 5 1

Insect Damage 5 1

Mal-formed 5 1

Large Rock or Stick - Screen Size 18/19/20

Medium Rock or Stick – Screen Size 15/16/17

Foreign Defect Number Full Defects

Dried Cherry 1 1

Floater 2 1

Large Rock or Stick 1 5

Medium Rock or Stick 1 2

Small Rock or Stick 1 1

Large Skin or husk 1 1

Medium Skin or husk 3 1

Small Skin or husk 5 1

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Defects Type Points Defects Type Points

4 2 100 49 5-5 -55

4 2-5 95 53 5-10 -60

5 2-10 90 57 5-15 -65

6 2-15 85 61 5-2- -70

7 2-20 80 64 5-25 5/6 -75

8 2-25 2/3 75 68 5-30 -80

9 2-30 70 71 5-35 -85

10 2-35 65 75 5-40 -90

11 2-40 60 79 5-45 -95

11 2-45 55 86 6 -100

12 3 50 93 6-5 -105

13 3-5 45 100 6-10 -110

15 3-10 40 108 6-15 -115

17 3-15 35 115 6-20 -120

18 3-20 30 123 6-25 6/7 -125

19 3-25 3/4 25 130 6-30 -130

20 3-30 20 138 6-35 -135

22 3-35 15 145 6-40 -140

23 3-40 10 153 6-45 -145

25 3-45 5 160 7 -150

26 4 0 180 7-5 -155

28 4-5 -5 200 7-10 -160

30 4-10 -10 220 7-15 -165

32 4-15 -15 240 7-20 -170

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34 4-20 -20 260 7-25 7/8 -175

36 4-25 4/5 -25 280 7-30 -180

38 4-30 -30 300 7-35 -185

40 4-35 -35 320 7-40 -190

42 4-40 -40 340 7-45 -195

44 4-45 -45 360 8 -200

46 5 -50 >360 Above 8

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