Transcript Food Preservation

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.
2.
3.
4.
5.
EXTEND SHELF LIFE
MAINTAIN SENSORY PROPERTIES
MAINTAIN OR IMPROVE NUTRITIVE
PROPERTIES
ENSURE SAFETY
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.

Food Spoilage
Moldy oranges
Moldy cheese
Potato blight
The Objective!

Goal for Preserving Food:


Minimize or _____________ the
Enzymatic
activity of microorganisms, enzymes, browning is
caused by an
and chemical reactions that cause
oxidase enzyme
in apples,
food spoilage or foodborne illness
bananas,
avocadoes, and
How? By making conditions for
other foods
chemical/biochemical reactions
_______________, and/or by inhibiting
microbial growth
Food Spoilage and
Foodborne 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 methods
 Drying
 Salting
 Sugaring
 Pickling
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
Canning
Freezing
Drying
Jams/
Jellies
Methods of
Food
Preservation
Curing/
Pickling
Smoking
Fermenting
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.
Freezing


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
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
Scraped surface
Birdseye
Ice Cream
Immersion
In safe liquids that remove heat
Cryogenic liquid sprays
Liquid 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
Drying




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



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
2.
LOSS IN VITAMINS
º
º
3.
Digestibility can be reduced (high
temperatures)
Water soluble
Fat soluble
FATS:
º
Potential for oxidative rancidity
increases (high temperatures)
NUTRIENT CHANGES AND OVERALL
QUALITY (cont.)
4. CARBOHYDRATES:
º
º
º
Enzymatic and nonenzymatic browning.
Carmelization increases
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.)
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
2.
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 foodborne illness microorganisms. It also
reduces microbial load, inactivates
enzymes, and extends shelf life.
BEER PASTEURIZATION:
1.
2.
Use of heat before or after bottling
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 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.

Pressure Canning
Canning
Boiling Water Canning




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)
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.
B.
C.
ACID
SUGAR AND SALTS
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
FERMENTATION
Use 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.
3.
4.
5.
6.
Source of energy
Oxygen availability
Temperature
pH
Aw
Food Fermentation Basics

Only food preservation in which
microbial growth is encouraged
Fermenting


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
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





MaltBeer
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
Pickling

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
 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.
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
Curing &
Smoking



Salting reduces ______________
availability to microbes, chemical &
biochemical reactions
Poultry, meat, game, seafood
Nitrates & nitrites added also inhibit
C. botulinum


May or may not smoke afterward


________________ consumption
also linked to stomach cancer
Smoking adds appeal in taste &
appearance
Heat, chemicals, and surface
dehydration work to preserve food
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 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
(entrance of meat)
Prototype processing line
Minced salted meat intoduction
Prototype processing line
Filling and ribbon extrusion device
Prototype processing line
Rolling Mill
Prototype processing line
End of line
Dried and restructured meat roll
SOME POSSIBILITIES OF PRODUCTS
Dried piece of meat grilled like flavoured or jerky meat
SOME POSSIBILITIES OF PRODUCTS
Peperoni or chorizo like garnish for pizza
SOME POSSIBILITIES OF PRODUCTS
Pork meat with vegetables
SOME POSSIBILITIES OF PRODUCTS
Red turkey meat rolled and coated with spices
SOME POSSIBILITIES OF PRODUCTS
Beef meat rolled with cheese
SOME POSSIBILITIES OF PRODUCTS
Catering component for
cold lunch
Catering componants for
hot dishes
Beef meat rolled and
stuffed with apricot,
prune, etc.
Meat roll stuffed with
vegetables
Snacks (eventually spiced)
Pork meat flavoured like
dried ham (20% of dried
ham trimming)
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
CONCERNS
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.
A.
TYPES OF RADIATION PROCESSES



RADURIZATION - Reduce number of
common spoilage organisms - extends
shelf life.
RADICIDATION - Elimination of nonspore forming pathogenic bacteria.
RADAPPERTIZATION - Commercial
sterilization of foods.
Irradiation
Food is exposed to gamma rays or Xrays
 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.
2.
3.
Increased knowledge and
acceptance
Decrease in microwave cost and
size
Consumer lifestyle
Radiation

Gamma Radiation
1. Used to Sterilize Food
2. Kill Insects & Parasitic Worms
3. Prevent Sprouting of Fruits and
Vegetables
Radiation Treatment of Foods
Wheat Flour
White Potatoes
Pork
Fruit
Vegetables
Spices
Vegetable Seasonings
Poultry
Frozen Meat
Case 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, NJ
In 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