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  • TROPICAL FRUIT TECHNOLOGY BY N. CZYHRINCIW

    Department of Chemistry and Technology, Faculty of Agronomy, Central Uniuersity, Maracay, Venezuela

    I. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11. The Significance of Fruits . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

    111. Morphology and Anatomy of Fruits . . . . IV. Physical Properties of Fruits ............................................. 165 V. Some Chemical Properties of Fruits . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 174

    ......................... 163

    A. Color, Aroma, and Flavor. ............................................ 174 B. Vitamins and Mineral Salts . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 179 C. Carbohydrates, Proteins, Fats, and Caloric Value ....................... 182 D. Enzymes . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 183 E. Other Substances . . ........................... 185

    . . . . . . . . . . . . . . . . . . 185 A. Preservation of Fresh Fruits and Freezing.. ............................ 185 B. Separation of the Inedible Part (Skin). ................................. 188 C. Obtaining Juices, Pulps, and Concentrates ............................. 190

    ................................... 194 E. Sweet Products. . . . . . . . . . . . . ................................... 195 F. Fermentation Products -Alcoholic and Acetic ......................... 196 G . Age of Elaborated Products ........................................... 199 H. Preservation by Irradiation ........................................... 204

    VII. Conclusion . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 204 References . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 207

    VI. Technical Problems ...............................

    D. Dehydrated Products . . . . . . . .

    I. INTRODUCTION

    With the expansion of the food industries at the beginning of the twentieth century, the science of food technology was established for study of the preservation of edible agricultural products in their natural state, and for the study of cheap and practical methods of processing foodstuffs, to preserve them and improve their quality.

    Processing is the series of manufacturing operations that transform the natural structure and change the proportions of the substances

    153

  • 154 N . CZYHRINCIW

    initially present in the raw materials. The science of food technology is concerned with study of the physical and chemical properties of the raw materials and the finished products, of the manufacturing processes, of the machinery used, and of the analyses used-organo- leptic, physical, chemical, and bacteriological.

    Many modern industrial processes are based on ancient experience gained in primitive manufacturing and rural handicrafts. Desrosier (1961), for example, presented a historical survey of methods of cereal preservation known for thousands of years. H.: refers to the ancient civilizations of the Middle East, of India, of the Inca Empire in Peru, etc. Such products as salted and pickled fish, cured meats, fermented drinks, bakery goods, etc., were commonly sold in the markets of the Roman Empire. Storni (1942) reports that the ab- origines of South America had developed processes to preserve certain food products, and that they could manufacture flour, sweets, beverages, and other things. Friedman (1963) states that many of our established methods of food preservation and food processing come from prehistorical times, and their safety has been tested in the crucible of human experience, not always, however, definitively and with finality.

    Studies in food technology cover various fields, characterized either by the nature of the raw materials (e.g., cereals, fruits, meats) or by the common processes of manufacturing and the resulting similarities in the finished products (e.g., bread baking, canning, bottling of soft drinks).

    As a part of food technology we study fruits, particularly the prob- lems presented by tropical fruits.

    The development of the several fields of food technology is very important in the social and economic life of all countries, as may be seen from the history of Australia, where the great boom in the past century in farming and stock raising was brought about by the develop ment of frozen-meat technology and canning industry, which made it possible for high-quality products at satisfactory prices to be exported to the markets of distant and thickly populated Europe. Peterson and Tressler (1963) consider the social and economic development of Australia to be almost an ideal case.

    The industrialization of pineapple in Hawaii is another example of the significance of food technology. The growing and processing of pineapple in Hawaii has become a principal occupation of the people of the island. New, thoroughly mechanized factories produce 57% of the worlds canned pineapple and 82% of its pineapple juice (Cushing, 1960).

  • TROPICAL FRUIT TECHNOLOGY 155

    In the United States 28% of industry is concerned with food processing, employing 13.2 90 of the national working force (Parker et al., 1952). It may be noted that during the last twenty years, the consumption of frozen foods has increased eight times, and that of baby foods 42 times (Proctor, 1960). In England, the consumption of canned juices has increased 400% in the last five years.

    The development of agriculture in distant areas would be im- possible without modern technology to preserve and process farm products. Desrosier (1961) has estimated that the present world population will have doubled in the next forty years, from three billion to six billion; the demand for foodstuffs will grow proportion- ally. Areas in the temperate zone suitable for growing wheat or rye will soon be totally occupied; meanwhile, huge areas suitable for rice and corn lie untouched in the tropics. Also, land suitable for growing the white sugar beet (Beta uulgaris) soon may not be avail- able. Although scientific research has increased the sugar content of this root from 6 to 18% within the last century, it does not seem probable that this can be carried any further. However, there is no shortage of space for growing sugar cane in the tropics.

    Equally vast possibilities exist in the tropics for the cultivation of other crops, especially for fruit plants. Thus, a great future may be expected in tropical farming, and inevitably, a parallel develop- ment in tropical food technology. This advance in tropical farming will occur sooner than the production of synthetic foods mentioned by Proctor (1960), despite the fact that the cost of many synthetic vitamins has decreased by almost half during the last six years, according to Fox (1963).

    Food technology must prepare in advance to respond to its future role as a principal factor in food production and processing. Desrosier (1961), in his absorbing book, has explained the possibilities of food production in the new tropical zones, and also its main technical difficulties. Wickiner (1960) has also discussed important aspects of farming in Asia, Africa, and Latin America.

    Food technology, particularly fruit technology, in the tropics is determined by certain specific conditions.

    (1) Natural fruit resources are potentially enormous. One recalls Humboldts calculation that the growing of 33 kg of wheat and 90 kg of potatoes requires the same ground area as the growing of 4000 kg ofbananas (Nicholls, 1901).

    There are many obscure fruit plants in the wild or semi-primitive state. The time necessary for growing plants to the first crop is rela- tively short in the tropics; this is an important factor in planning and

  • 156 N. CZYHRINCIW

    forecasting needs for raw materials. For example, papaya and passion fruit trees start to bear at the end of the first year; cashew at the third year; the mango tree between the fourth and sixth years; and the coconut from five to eight years. Another advantage is that since fruit crops ripen at different times in the tropics the manufacturing processes can work on freshly harvested fruits almost all year long.

    (2) Transport of harvests and technological processes are usually carried out at high temperatures. Van't Hoff established that every increase in temperature of 10C speeds chemical reactions two to three times. This necessitates special study on desirable or undesir- able biochemical processes, autoxidation, and, particularly, on tin- plate corrosion. Temperatures in production departments and storage houses always range between 22" and 32C. Other negative factors, such as strong sunlight and high seasonal humidity, affect the manu- facturing and storage of raw materials and elaborated products.

    (3) In the future development of tropical-fruit technology, export to far markets should be taken into account. Such factors as the conditions of manufacturing and packaging the semifinished prod- ucts, as well as the stability of the exotic products, will be of great importance.

    (4) It is probable that the products of a majority of tropical countries will be less contaminated by radioactive elements than the products of more northerly countries, as may be confirmed by comparative determinations of radioactive contamination made by Solanas et u1. (1964).

    (5) Since the larger and more experienced research institutions have been located in temperate and subtropical climatic zones, different aspects of the technology of

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