Food Preservation Through Processing

Freezing, Drying, Canning, Fermentation and

Irradiation

History and Trends of Food Preservation

Food Science

Unit 7

Objectives Student’s will be able to:

Define food preservation Summarize five common historical methods of

food preservation Describe current technologies for food

preservation Discuss current trends in food preservation

Activity

Why does fresh bread go bad? Why do fresh donuts go bad? Why do packaged bread or donuts not go

bad?

WHY PROCESS FOODS?

1. EXTEND SHELF LIFE 2. MAINTAIN SENSORY PROPERTIES 3. MAINTAIN OR IMPROVE NUTRITIVE

PROPERTIES 4. ENSURE SAFETY5. BOTTOM LINE:  $$ (ECONOMIC

VALUE)

Food Preservation Methods of treating foods to delay the

deterioration of the food. Changing raw products into more

stable forms that can be stored for longer periods of time.

Allows any food to be available any time of the year in any area

of the world.

Moldy oranges

Potato blight

Moldy cheese

Food Spoilage

The Objective!

Goal for Preserving Food: Minimize or _____________ the activity

of microorganisms, enzymes, and chemical reactions that cause

food spoilage or foodborne illness How? By making conditions for

chemical/biochemical reactions _______________, and/or by inhibiting microbial growth

Enzymatic browning is caused by an

oxidase enzyme in apples, bananas,

avocadoes, and other foods

Food Spoilage andFoodborne Illness

(part 1)

Food Spoilage:

Altered smell, taste, texture, appearance

The appearance of spoilage signs tells you that the conditions for the growth of illness-causing bacteria could have occurred

Could be caused by enzyme or other chemicals, too; not necessarily

to eat

Food Spoilage and Foodborne Illness

(part 2)

Foodborne Illness:

Mostly caused by bacteria Some microbes cause human illness by

producing toxins, but may not produce food spoilage

Over 76,000,000 Americans get some form of foodborne illness every year

(from “intestinal distress” to death)

Historical Methods of Food Preservation

Primitive and tedious methodsDryingSaltingSugaringPickling

Drying

Used to preserve fruit, vegetables, meats, and fish.

Mainly used in the south – warmer climate.

Causes the loss of many natural vitamins.

Salting

Used extensively for pork, beef, and fish.

Costly due to high price of salt. Done mainly in cool weather

followed by smoking.

Sugaring

Used to preserve fruits for the winter.

Jams and jellies. Expensive because sugar

was scarce commodity in

early America.

Pickling

Fermenting Used to preserve vegetables. Use mild salt and vinegar brine. Increases the salt content and reduces

the vitamin content of the food. Oldest form of food preservation.

Current Technologies in Food Preservation

Methods of Food

Preservation

CanningFreezing

Drying

Curing/

SmokingFermenting

Pickling

Jams/ Jellies

PRESERVATION OF FOODS BY LOWERING THE TEMPERATURE

THEORY - LOWERING THE STORAGE TEMPERATURE OF THE FOOD WILL REDUCE OR PREVENT

SPOILAGE BY MICROORGANISMS AND/OR CHEMICAL REACTIONS.

NOTE:   TECHNOLOGY IS RELATIVELY NEW ENERGY INTENSIVE

I. REFRIGERATION - Temperatures typically between 45 - 32° F (7.2 - 0° C). Prefer below 38° F.

THEORY - LOWER TEMPERATURE WILL REDUCE SPOILAGE.

ALTER GASES: Controlled atmosphere storage: increase carbon dioxide and lower oxygen to slow respiration of tissues or microorganisms in fruits, vegetables, nuts, meats and eggs.

ISSUE - Spoilage organisms and chemical reactions can occur at refrigerator temperatures. But at a slower rate e.g. lower shelf life.

CONCERNS:

1. Some pathogenic microorganisms can grow at these temperatures.

2. Cross-contamination in refrigerator.

3. Odor transfer

4. Spoilage

TRADITIONAL REFRIGERATED FOODS

1. Fresh foods (unprocessed), fruits and vegetables, (fresh meats, poultry, fish)

2. Processed foods: doughs, minimally processed vegetables

3. Refrigerated foods containing fruits and vegetables: entrees, dinners, salads. (Pasteurized dairy products cured meats)

WHY DO WE SEE MORE NEW REFRIGERATED FOODS ENTERING THE MARKETPLACE THAN OTHER FOODS?

1. Consumer demand for high quality foods:

A. Typically less change in the quality of food product.

B. Convenient - shorter cook times

2. Changes in food distribution

A. Buying habits

B. Improved food distribution

3. Improved processing  techniques

A. Aseptic processes

B. Gas storage (CA and map)

Cold:

Most microbial growth slows at temperatures under 50 F. Some bacteria, called psychrophiles, actually thrive at relatively low temperatures and will continue slow growth. Foods frozen at less than 14 F usually do not have any free water, so these foods also benefit from low water activity to help protect against microbial growth. Freezing may kill some but not all of the microorganisms.

Refrigeration:

some fresh produces can rapidly deteriorate under unrefrigeration, which affect the EP cost to be greater. Some precuts and convenience fresh produces such as salad greens should be delivered at temperature of approximately 34 ̊ F to 36 ̊ F.

Refrigeration

Early time, ice and snow was used.

Now the most popular method of food preservation.

85% of all foods are refrigerated. Greatly changed our eating habits.

Most convenient, easiest, fastest method

Low temperatures slow down chemical/biochemical

reactions Inhibit microbial growth

Freezing fruits is sooooo easy! Spread out clean dry berries on a

cookie sheet, put into the freezer; when they’re frozen, put into a freezer bag

Stone fruits like peaches can be packed in syrup in Tupperware or plastic bags OR dry-packed after sprinkling with sugar & freezing in bags or boxes

Freezing

II. FREEZING – TEMPERATURES

• < 32 F (0° C)

• Change in water from liquid to solid.

THEORY: 

1. Lower temperature. Will reduce spoilage.

2. Water is unavailable for microorganisms and chemical reactions.

WHY FREEZE?

1. In general frozen foods are better nutritionally and organoleptically than other processed foods.

2. Long shelf life

3. Convenient - shorter cook times

DISADVANTAGE:    Energy intensive

ISSUES W/ FROZEN FOODS

1. Chemical reactions can occur in unfrozen water.

A. Some foods blanched or sulfited before freezing.

B. Vacuum packaging to keep out oxygen.

ISSUES W/ FROZEN FOODS (cont.)

2. Undesirable physical changes

A. Fruits and vegetables lose crispness

B. Drip loss in meats and colloidal type foods (starch, emulsions) Freeze product faster Control temperature fluctuations in

storage. Modify starch, egg systems, etc.

UNDESIRABLE PHYSICAL CHANGES (cont.)

C. Freezer burn Package properly Control temperature fluctuations in storage.

D. Oxidation Off-flavors Vitamin loss Browning

E. Recrystallization

TYPES OF FREEZING:

1. AIR FREEZING - Products frozen by either "still" or  "blast" forced air.

• cheapest (investment)

• "still" slowest more product changes

• "blast" faster, more commonly used

2. INDIRECT CONTACT - Food placed in direct contact with cooled metal surface.

• relatively faster

• more expensive

TYPES OF FREEZING (cont.):

3. DIRECT CONTACT - Food placed in direct contact w/refrigerant (liquid nitrogen, "green" freon,  carbon dioxide snow)

• faster

• expensive

• freeze individual food particles

Freezing Freezing and refrigeration are among

the oldest methods of food preservation. 1920s Clarence Birdseye pioneered

research on quick freezing processes For frozen storage food must be kept

solidly frozen – temps of -18° or lower In frozen foods it is very important to

make sure the internal water is completely frozen; unfrozen H20 can promote spoilage

SLOW FREEZING VS FAST FREEZING

Slow freezing Large crystal growth Cell dehydration

Fast freezing Small crystal growth Best for quality foods

Freezing The lowering of a products temperature

to below approx -10°C Decreases rates of chemical change

and stops growth and metabolism of microorganisms

Processes include: Blast Freezing – packaged foods Fluidized Bed Freezing– Individual Quick

Frozen Products Immersion Freezing – Juices Scraped Surface Freezing – Ice Cream

Different ways to Freeze

Plate Freezing

Box and plates Birdseye

Scraped surface Ice Cream

Immersion

In safe liquids that remove heat

Cryogenic liquid spraysLiquid N2, CO2, Freon

Affect of Freezing on Nutrition

If frozen food is handled properly, most water soluble vitamins will remain available but some degradation will occur over time

The real problems occur when foods go through freeze-thaw.This affects quality characteristics as well as nutritional value

Reduce moisture content prevents spoilage microbes from growing, as well as enzymatic & chemical reactions

Taste, appearance, & nutritive value not preserved the way they are with canning or freezing

Makes good snacks Dried foods conserve storage

space

Drying

Drying The dehydration of foods Removing 95%-99% of water from a

product by means of various process Processes include:

Tunnel Drying – vegetables, fruits Drum Drying – potato flakes Spray Drying – coffee Freeze Drying – drinks, instant meals

DRYING

Probably oldest form of food preservation Most widely used preservative method

THEORY:  REDUCING THE AMOUNT OF FREE WATER WILL PREVENT MICROBIAL AND CHEMICAL SPOILAGE

DRY FOODS - Aw OF 0.2 TO 0.6 < 0.6 prevents microbial growth 0.2 - 0.3 prevents many chemical

reactions.

INTERMEDIATE MOISTURE FOODS 0.8 to 0.9 Use mold inhibitors

ADVANTAGES OF DRIED FOODS

1. Less costly to produce

2. Less costly to store and transport

NUTRIENT CHANGES AND OVERALL QUALITY

1. PROTEINS: º Digestibility can be reduced (high

temperatures)

2. LOSS IN VITAMINS º Water soluble º Fat soluble

3. FATS: º Potential for oxidative rancidity

increases (high temperatures)

NUTRIENT CHANGES AND OVERALL QUALITY (cont.)

4. CARBOHYDRATES: º Enzymatic and nonenzymatic browning.

º Carmelization increases

º Prevent or reduce color changes:

• sulfites

• blanching

5. SHAPE CHANGES

STORAGE (KEEP OUT O2 AND LIGHT)

1. Air space (vacuum)

2. Reduce exposure to light 3. Good moisture barrier

TYPES OF DRYING

A. SUN DRYING Slow process Problems: no control Microorganisms and pests can attack Rain High nutrient loss Inexpensive products: grains, acid fruits,

spices

TYPES OF DRYING (cont.)

B. HOT AIR DRYING More efficient/control Lower nutrient loss More expensive Products: dried vegetables, pasta, some

fruits

C. DRUM DRYING More efficient than hot air Lower nutrient loss Cost about equal with air Products: potato pastes & slurries

TYPES OF DRYING (cont.)

D. SPRAY DRYING Low nutrient loss More expensive than drum or air drying Good control/efficiency Use only for liquids Products: milk, instant tea and coffee

E. PUFF DRYING:  PRESSURE DROP Using heating systems; Air poppers;

Extruders.

TYPES OF DRYING (cont.)

F. FREEZE DRYING Best nutrient quality Best product quality (shape;

rehydration) Most expensive Good control Products: coffee, camping foods,

military, NASA

TYPES OF DRYING (cont.)

G. HOT OIL Good heat transfer Good control Distinctive flavor/aroma Oil uptake, mouth feel/hand/calories Oxidation, free fatty acid,

and flavor concern Products: potato chips, french fries, onion

rings, some popcorn, doughnuts, some specialty meats (different countries)

TYPES OF DRYING (cont.)

H. CHEMICAL DRYING Salt Sugars

I. SMOKING: Heat and wood smoke

Drying

Objective is the eliminate H2O with minimum damage to food by getting heat into the food and moisture out

Removal of water eliminates multiplication of bacterial cells

Drying is sometimes done in the presence of chemicals such as SO2, Ca or Na propionate to control microorganisms

Drying:

Drying reduces the water activity (Aw) in a food. Since microorganisms contain about 80 percent moisture, drying or dehydrating the food also dehydrates the microorganism. Changing the amount of water in a food also alters the rate of enzyme activity and other chemical reactions.

Freeze Drying

The food is first frozen and then put into a vacuum chamber

A small amount of heat is applied Under the reduced pressure of the

vacuum, the water, instead of going to a liquid state, is changed directly into vapor

Lengthy process (10–20 h) that leaves food with 1-4% moisture content

Freeze Drying Advantages

Fresh flavors and textures better preserved over drying

Reduced transportation and storage costs

Refrigeration unnecessary Nutritive value remains very similar to

the fresh product

HEAT PROCESSING: Use of high temperatures to destroy enzymes and microorganisms that could reduce quality and/or safety of food

1. BLANCHING - A mild heat treatment that primarily destroys enzymes and reduces microbial load (does not necessarily kill pathogens), further preservation methods needed to extend shelf life.

Example: Vegetables, frozen, canned

2. PASTEURIZATION - A mild heat treatment used primarily to destroy pathogenic organisms but it also destroys enzymes and reduces microbial load. Requires an addition preservation method to extend shelf life (example: refrigeration, drying).

3. COMMERCIAL STERILIZATION – A severe heat treatment that destroys pathogenic and many microorganisms that could spoil food. Extends shelf life, room temperature stable. (canned foods)

4. STERILIZATION - A very severe heat treatment that destroys all microorganisms.

FACTORS INFLUENCING CHOICE OF HEAT TREATMENTS

1. Type of food

º a. pH • Low acid: 5.0 - 6.8. Meat, dairy, vegetables

• Medium acid: 4.6 - 5.0. Soups, vegetables • Acid: 3.7 - 4.5. Fruits • High acid: 2.3 - 3.6.Citrus fruits, berries

º In medium & low acid (>4.5 pH) Foods, the canning process is designed to kill C. Botulinum.

FACTORS INFLUENCING CHOICE OF HEAT TREATMENTS (cont.)

2. Level of contamination 3. Presence of oxygen 4. Heat resistance of organisms or

enzymes 5. Heat penetration

º characteristics of the food 6. Packaging material 7. Size of container 8. Sensory qualities desired

BLANCHING OF FRUITS AND VEGETABLES

OBJECTIVES:

1. Inactivate enzymes**

A. Metabolic

B. Maintain color

C. Texture

D. Flavor  

E. Nutritive value

BLANCHING OF FRUITS AND VEGETABLES

OBJECTIVES (cont.):

2. Lower microbial load (combination of rinsing action and heat)

3. Aids in packaging – wilts vegetables and removes respiratory gases

4. Removes dirt, leaves, etc.

5. Aids in peeling

DRY BEANS: Must be partly rehydrated before blanching can take place. Multiple blanchers or long water blanchers are used. Where does the rest of the water come from to finish the thermal process (example: canned chili). How long do you cook the canned dried beans?

ADEQUACY OF BLANCHING:

Enzyme tests:

• Peroxidase

• Catalase

• Lipoxygenase

Physical:

• Wilting

• Color

PASTEURIZATION

Used for milk, liquid eggs, fruit juices and beer.

Destroy pathogens Reduce microbial load   (numbers) Inactivate enzymes Extend shelf life

MILK PASTEURIZATION: Based upon T.B. Microorganism; Test for adequacy using phosphatase (blue color test).

• Vat: 145° F (62.8° C) for 30 minutes

• HTSH:161° F (71.7° C) for 15 seconds

• 191° F (88.3° C) for 1 second

• 194° F (90° C) for 0.5 second

• UHT: 275-284° F (135 to 140° C) for a few seconds

CREAM:  150-155° F (65.6-68.3° C) For 30 minutes

166-175° F(74.4-79.4° C) For 15 seconds

EGG PASTEURIZATION: Based upon killing and preventing growth of salmonella (food-borne illness microorganism).

Liquid eggs heated to 140-144° F (60-62° C) and held for 3.5-4.0 minutes. Often sugar or salts are added. Why?

FRUIT JUICE PASTEURIZATION: New to kill E. Coli 0157:H7 And/or other food-borne illness microorganisms. It also reduces microbial load, inactivates enzymes, and extends shelf life.

BEER PASTEURIZATION:

1. Use of heat before or after bottling

2. Cold pasteurization - sterile filtering: better flavor than heat pasteurization not to be confused with irradiation.

Pasteurization The elimination of

pathogenic bacteria and reduction in numbers of spoilage bacteria.

Ensures a safe product and extends shelf life

Often used during production of: Milk Honey Beer Juices

Pasteurization

Foods heated to a certain temp for a certain amount of time to kill harmful bacteria

Milk most commonly pasteurized food – beer, wine and fruit juices also pasteurized

Milk heated to 63°C (145°F) for 30 minutes

Pasteurization

UHT pasteurization – ultra high temperature

Foods heated to 138°C for 2-4 seconds UHT allows food to retain more nutrients

and better flavor

Heating Started in 1800’s. Known as canning – putting hot food in

jars to seal. Food is cooked to extremely high

temperatures, put into jars and lids are placed on them.

Lids are sealed from the heat and this prevents bacteria from growing and spoiling the food.

Heating

Preserves food by heating to high temperatures, driving out O2, and forming a __________________

_________________ water kills most bacteria, except for C. botulinum spores

For high-acid foods (pH < 4.6), boiling water (212 F) is OK

For low-acid foods (pH > 4.6),

must use pressure canning to get temperature above 240 F (where C. botulinum spores are killed)

CanningPressure Canning

Boiling Water Canning

Canning

The process of sealing a food in an airtight container and destroying all microorganisms by heating

The sterilization temperature is dependant on pH:

pH Temperature

4.6 or greater > 121°C

4.5 or lower < 100°C

Canning

Uses heat and pressure to eliminate microorganisms and enzymes

Allows foods to be safely kept for extended periods of time – months to years

Bacteria, particularly those in spore form, may be less readily destroyed than other organisms during this process except in the presence of acid – has led to botulism

Canning

Disadvantages Changes in color and texture Produces foods with cooked flavor Heat liable and water soluble vitamins

will be lost during canning

FOOD ADDITIVES -   PRESERVATIVES THAT INHIBIT MICROORGANISMS

A. ACID

B. SUGAR AND SALTS

C. ANTIMICROBIAL AGENTS

Food Preservatives

Retard or reduce the growth of undesirable microorganisms, mold and bacteria.

Do not affect from food texture or taste. Safe for human consumption. Extend shelf-life of food.

Shelf-life – length time before a food product begins to spoil.

Chemicals:

Chemical additives such as sodium benzoate, sorbic acid, sodium or calcium propionate and sulphur dioxide retard the growth of microorganisms, modify enzyme activity, inhibit chemical reactions or modify the structure of foods

Chemical Additives sodium nitrate

fatty acids sulfur dioxide

sorbic acid diethyl pyrocarbonate

oxidizing agents benzoates antibiotics

antioxidants

Food Fermentation

FERMENTATIONUse of microorganisms to convert foods (raw

commodities) into a more stable form.

Typically the conversion of carbohydrates into acid or alcohol. Some additional antimicrobial compounds may be formed.

THEORY:  Reduce the pH of the food or produce substances which make the environment uninhabitable by other organisms.

FACTORS THAT INFLUENCE FERMENTATION

1. Type of organism º natural or starter

º acid, oxygen, temperature,

º salt tolerance

2. Source of energy

3. Oxygen availability

4. Temperature

5. pH

6. Aw

Food Fermentation Basics

Only food preservation in which microbial growth is encouraged

Encourages the growth of some bacteria, which consume part of the food & create __________________

Example: Yogurt, formed when bacterial culture is added to milk Bacteria eat milk sugars

(lactose) & form _______________ acid

The pH drops, which inhibits the growth of other bacteria

Fermenting

Food Fermentation Metabolic activities occur during

fermentation that: Extend shelf life by producing acids Change flavor and texture by producing

certain compounds such as alcohol Improve the nutritive value of the product

by: Microorganisms can synthesize vitamins Breakdown indigestible materials to

release nutrients, i.e., bound nutrients

Fermented Foods Foods fermented by

yeast MaltBeer Fruit (grapes) Wine Rice Saki Bread dough Bread

Foods fermented by mold Soybeans Soy

sauce Cheese Swiss

cheese

Foods fermented by bacteria Cucumbers Dill

pickles Cabbage Sauerkraut Cream Sour cream Milk Yogurt

Works in 2 ways Adding organic acids (vinegar) Adding a desirable culture to produce an organic

acid The goal: Lower acidity of food to <

4.5________ , below which most microbes can’t live

Further heat processing destroys the remaining organisms and enzymes

Pickling

1.) Rinse the cabbage, then quarter lengthwise

4.) Mixing the other ingredients with the ground red chiles to make a paste

2.) Sprinkle the cabbage quarters with salt, making sure you get salt into each layer of leaves. Place the cabbage into a plastic bag and wait for 30 min – 1 hr, pressing down occasionally. Rinse, and squeeze out extra water.

5.) Smear the paste in between each layer of the cabbage.

3.) Ingredients for the kim chee: green onions, daikon radish, ginger

6.) Roll the cabbage sections, and pack

them tightly into an

airtight container

Curing

One of the oldest forms of preservation Used with meat and fish Involves adding some combination of salt,

sugar, spices, vinegar, or sodium nitrate to animal foods

Sometimes used in conjunction with smoking – bacon and sausage

Salting reduces ______________ availability to microbes, chemical & biochemical reactions

Poultry, meat, game, seafood Nitrates & nitrites added also inhibit

C. botulinum ________________ consumption

also linked to stomach cancer May or may not smoke afterward

Smoking adds appeal in taste & appearance

Heat, chemicals, and surface dehydration work to preserve food

Curing & Smoking

Very strong & statistically significant correlation between increased nitrate/nitrite consumption (in water or preserved foods) and stomach cancer

Sugar, salt and smoke:

Sugar, salt and smoke are chemical means of controlling food deterioration. The addition of sugar or salt to a food item increases the affinity of the food for water. This removes the water from the microorganism through osmosis.

Smoke contains formaldehyde and other preservatives. The heat involved with adding the smoke helps reduce the microbial populations and it dries the food somewhat.

Chemicals

Salt was first chemical used to preserve foods.

NaCl – salt; makes water unavailable to microorganisms.

Changes the pH of the food not allowing microorganisms to live.

Curing

Preserves food by removing or binding H20 so it is not available for microorganism growth

Impart distinctive flavor and color to food

Food Packaging

Atmosphere:

Changing the storage atmosphere reduces food deterioration. The growth of aerobes is slowed by removing the oxygen, while providing oxygen limits the growth of anaerobes. Adding carbon dioxide or nitrogen also slows deterioration.

Food Packaging

Packaging is what allows food to be transported from the processor to the consumer in a wholesome state

Food Packaging

Makes food easier to handle Protects food from environmental

conditions Locks out microorganisms Prevents physical and chemical

changes Maintains nutritional qualities

Food Packaging

Materials used include: Metal, glass, paper, paperboard, plastic

Packaging choices are made to compliment the food Since oxidation will make vegetable oil

become rancid, it is packaged in containers impermeable to O2

Types of Packages MAP – modified atmosphere packages

used to store contents in a gas other than air

Biodegradable – packages that will decompose over a relatively short amount of time in a landfill

Benefits of the technologyBenefits of the technology

Osmofood provides a unique opportunity to increase the valorization of low added value muscles and is applicable to all meats (beef, pork, chicken, turkey, etc.)

Osmofood opens new niche markets for meat consumption (snacking,luncheon meat...) and allows the creation of new and innovative products with superior texture and flavor and extended shelf life(AW<0.9)

Because it involves an osmotic process, Osmofood has a decontamination effect (2 log reduction for Salmonella, Listeria monocytogenes, E.coli ... to 5 log reduction with a final flash heating in a warm osmotic solution)

Pilote for 120kg/h dried product Pilote for 120kg/h dried product (entrance of meat)(entrance of meat)

Prototype processing linePrototype processing lineMinced salted meat intoductionMinced salted meat intoduction

Prototype processing linePrototype processing lineFilling and ribbon extrusion deviceFilling and ribbon extrusion device

Prototype processing linePrototype processing lineRolling MillRolling Mill

Prototype processing linePrototype processing lineEnd of lineEnd of line

Dried and restructured meat rollDried and restructured meat roll

SOME POSSIBILITIES OF PRODUCTSSOME POSSIBILITIES OF PRODUCTS

Dried piece of meat grilled like flavoured or jerky meat

Peperoni or chorizo like garnish for pizza

SOME POSSIBILITIES OF PRODUCTSSOME POSSIBILITIES OF PRODUCTS

Pork meat with vegetables

SOME POSSIBILITIES OF PRODUCTSSOME POSSIBILITIES OF PRODUCTS

Red turkey meat rolled and coated with spices

SOME POSSIBILITIES OF PRODUCTSSOME POSSIBILITIES OF PRODUCTS

Beef meat rolled with cheese

SOME POSSIBILITIES OF PRODUCTSSOME POSSIBILITIES OF PRODUCTS

Snacks (eventually spiced)

Pork meat flavoured like dried ham (20% of dried

ham trimming)

Catering component for cold lunch

Beef meat rolled and stuffed with apricot,

prune, etc.

Catering componants for hot dishes

Meat roll stuffed with vegetables

SOME POSSIBILITIES OF PRODUCTSSOME POSSIBILITIES OF PRODUCTS

WHAT IS IRRADIATION PROCESSING?

Exposing food to gamma rays, x-rays or electrons to improve shelf life and safety.

Irradiation breaks chemical bonds killing microorganisms, insects and inhibits ripening in fruits.

Key advantage:  no heat generated

SOURCES

A. GAMMA RADIATION - Cobalt 60 or cesium 137 (radioactive isotopes).

B. X-RAYS AND ELECTRONS - Generators (ex. ISU Linear Accelerator Facility - LAF)

º Advantage: can be turned on or off. ABSORBED ENERGY MEASURED

IN RADS AND GRAYS

WHY IS RADIATION CONSIDERED AN ADDITIVE ?

Thought that it would change the nature of the food. In many other countries it is a process.

By law any food irradiated requires the Radura symbol.

Approved in 52 countries. Netherlands major user.

PROCESSING AFFECTS ON FOODS Food does not become radioactive “Unique Radiolytic Products are 

developed "(URPs)

º are they unique?

• pears get mushy

• milk becomes rancid

NOT ONLY FOOD ARE IRRADIATED

A. PHARMACEUTICALS AND SUPPLIES

º plastic disposable items

º note: things typically destroyed by heat. stopped using gas (ethylene oxide) due to safety reasons

B. PACKAGING MATERIALS º food cartons

º note: materials that come into contact with food.

C. WASTES º hospitals

º research labs

º note: prevent contamination of sewers.

D. MISCELLANEOUS º mascara

º sanitary napkins

º baby bottle nipples

º note: things in contact with body.

FOODS IRRADIATED TODAY

Grains - kill insects (no fumigation gases)

Tubers - inhibits sprouting

Spices – kills bacteria and insects

Vegetables and fruits - kill pests

Pork - control Trichinae

Poultry - kill salmonella

Beef - kill E. Coli 0157:H7

Hospital meals - persons with low immunological resistance

NASA meals

CONCERNSA. NUTRITIONAL EFFECTS

º Vitamins, proteins, enzymes.

º Example: thiamin in pork. Lose more cooking than by irradiation.

B. CARCINOGENS

º Example: benzene in eggs. More produced by more boiling than with irradiation.

C. MUTAGENICITY

º Example: may produce disease resistant microorganisms.

TYPES OF RADIATION PROCESSES

RADURIZATION - Reduce number of common spoilage organisms -  extends shelf life.

RADICIDATION - Elimination of non-spore forming pathogenic bacteria.

RADAPPERTIZATION - Commercial sterilization of foods.

Irradiation

Food is exposed to gamma rays or X-rays

Breaks down chemical bonds, cell walls and membranes and DNA

Rays strong enough to kill most bacteria, molds, and insects that may contaminate food

Irradiation

Delays ripening of fruits and sprouting of vegetables – leading to increased shelf life

Involves minimal heating -- has very little effect on taste, texture and nutritive value of food

Irradiation

First approved for use on Wheat and wheat flour in 1963

1999 – irradiation approved to curb pathogens in raw meats; it had already been approved and used for poultry products

Irradiation May experience wider usage as food

safety becomes more of an issue An effective way to reduce food-borne

hazards and ensure harmful organisms are not in the food we buy

Some special interest groups oppose irradiation – more attention needs to be paid earlier in food processing – others think it may cause toxic compounds to form in food; this is unproven

MICROWAVE HEATING

CONVERSION OF ELECTRICAL ENERGY TO MICROWAVE ENERGY TO HEAT FOODS (MAGNETRON)

Interacts with charged molecules and heats by friction• water • salt • sugars

Remaining heating takes place by conduction.

KEY DIFFERENCE BETWEEN MICROWAVE AND CONVENTIONAL HEATING. NO BROWNING OR CRISPING. WAYS TO SOLVE PROBLEM:

1. Color food

2. Combine with conventional heating

3. Use Suceptor (material that converts microwave energy to heat energy)

º Note - issue with Suceptor material and toxins in microwave oven.

FACTORS CAUSING UNEVEN HEATING IN THE MICROWAVE.

1. Nonuniform absorption of microwave energy

º Frozen foods

º Ice vs. Water vs. brine solution

º Compound food products

2. Irregularly shaped products

KEY TO GOOD MICROWAVE PERFORMANCE

• Follow manufacturers directions

NUMBER OF MICROWAVE OVENS HAVE INCREASED DRAMATICALLY IN THE PAST TEN YEARS

• 75% Population own microwaves.

WHY THE INCREASE

1. Increased knowledge and acceptance

2. Decrease in microwave cost and size

3. Consumer lifestyle

RadiationRadiation

Gamma Radiation

1. Used to Sterilize Food

2. Kill Insects & Parasitic Worms

3. Prevent Sprouting of Fruits and

Vegetables

Radiation Treatment of FoodsRadiation Treatment of Foods

Wheat Flour

White Potatoes

Pork

Fruit

Vegetables

Spices

Vegetable Seasonings

Poultry

Frozen Meat

Case Study Decatur, GeorgiaCase Study Decatur, Georgia

In June 1988, a capsule of radioactive cesium-137-- a waste product from nuclear weapons production-- sprung a leak at a Radiation Sterilizers plant near Atlanta. Though the leak was contained to the site, two of the three exposed workers spread radioactivity to their cars and homes. And an estimated 70,000 milk cartons, contact lens solution boxes and other containers were shipped out after they were splashed with radioactive water. Only about 900 of the contaminated containers were recalled. The ensuing taxpayer-funded cleanup cost more than $30 million, after which a government report concluded that "the public health and safety could have been compromised."

Case Study Dover, NJCase Study Dover, NJIn June 1986, two senior executives of Palo Alto, CA-based International Neutronics were indicted on federal charges of conspiracy, mail fraud and wire fraud in connection with an October 1982 spill of 600 gallons of water contaminated by radioactive cobalt-60. After a pump malfunctioned, workers were instructed to pour the radioactive water down a shower drain that emptied into the public sewer system. Workers were also ordered to wear their radiation-detection "badges" in such a way to falsify radiation levels. In the words of a federal prosecutor, company executives "bamboozled" Nuclear Regulatory Commission (NRC) inspectors by delaying an inspection of the facility, where food, gems, chemicals and medical supplies were irradiated. A $2 million cleanup included the cost to dispose of radioactive material at a nuclear waste dump in South Carolina. Company vice president Eugene O'Sullivan, a former member of the U.S. Atomic Energy Commission, was convicted of conspiracy and fraud in October 1986.