Egg preservation Residues in eggs Egg products Uses of eggs in non food industry

2. THE EGG IS A LIVING CELL WITH COMPLEX SYSTEM, FAVORABLE TEMP
AND BAD HANDLING FAVOR GROWTH OF M.O. AND INFLUENCE ITS
QUALITY
AIMS OF PRESERVATION:
1. PREVENT PENETRATION OF M.O.
2. PREVENT EVAPORATION OF MOISTURE
3. PREVENT MULTIPLICATION OF M.O.

3. METHODS OF PRESERVATION:
1. Small scale:
a. GLASS WATER:
EGG IS IMMERSED IN SODIUM SILICATE SOL., DRAIN ,DRY
PORES ARE SEALED WITH DULL APPEARANCE
B. LIME WATER:
4 PARTS OF SLAKED LIME, ONE PART SOD CHLORIDE,20
PARTS WATER. THE MIXTURE LEFT FOR A WEEK TO BECOME
CLEAR. EGG BECOMES ROUGH, IRREGULAR AND WHITE.
EGGS ARE STORED FOR ABOUT 4 MONTHS IN COOL PLACE.
C. USING OIL:
TO DECREASE MICROBIAL INVASION AND DECREASE LOSS
OF CO2 AND MOISTURE. LIGHT PARAFFIN OIL IS SPRAYED
ON SHELL WITH HAND OR AEROSOL SPRAYER

4. 2. Large scale:
a. Cold storage:
eggs are selected by general appearance and candling. Chilling
preserve most egg shell. Temp 0-1°C with 80- 85 % humidity are
common. Air circulation in storage room. Impregnation of shell with
colorless, odorless mineral oil. After several months, atypical flavor
may develop which is prevented by periodical sterilization with
disinfectant gas as ozone.
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5. b. Oil dipping:
eggs are dipped in light paraffin oil. All excess oil is
allowed to drain. Oil dipping is to prevent mold , before
oil dipping , eggs are dipped in sodium propionate 4%.
c. Storage under CO2 atmosphere:
storage room are charged with CO2 of concentration
2.5% with 85% relative humidity. The effect is more
potent at high temp. the quality of stored egg is
improved due to loss of CO2.
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6. Residues in egg
• Drug residues
• Hormonal
• Pesticides as insecticides, herbicides, fugicids
• Mycotoxins as aflatoxins, ochratoxins, citrinin
They have public health hazard and economical hazard. As
over use of such substances contaminates soil, water, crops, and
animal products(egg)
Effective control of handling such substances is important for
health and environmental protection.
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7. Detection of some residues:
1. Antibiotics and sulpha drug:
They are widely used in poultry industry as food additives to
promote growth and as a prophylactic agent against some
diseases.
eggs are washed carefully then the content are mixed.
2 ml of homogenized mixture with 20 ml of solvent then
centrifugation to separate supernatant.
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8. Microbiological assay by agar diffusion method is used with bacillus subtilis as test
organism then incubation of plates at 37°C for 6 hours.
Any zone of inhibition is positive result.
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9. 2. Organo chlorine, organo phosphorus, pesticide residues:
GC, GLC, HPLC using electron capture detector for organo
chlorine
Using flame photometric detector for organo phosphorus
Calculation of residues by matching the obtained curve with
standard one of organochlorine mixture previously prepared.
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10. Public health importance of residues:
•Antibiotic residues are responsible for certain allergic
reaction to consumers.
•It may create resistant pathogens which interfere with
treatment with such drugs (drug fastness)
•Long period consumption of egg with residues may lead to
death of commensals bacteria in GIT
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11. •Pesticids may lead to liver cirrhosis, respiratory infestation,
bone marrow effects, renal failure, soft tissue sarcoma, lung
and liver cancer
•Mycotoxins differ according to the dose , duration of
exposure, nutritional status, it may include : loss of appetite,
lack of weight gain, digestive disorders, neurological
abnormalities, hepatotoxic effect, jaundice, in advanced stage
it may lead to cancer and renal failure.
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12. Egg products
Def: it refers to eggs that are removed from their shells for processing
Functional properties of eggs and egg products:
It provide several functional properties in food industry as:
•Coagulation
•Emulsification
•Foaming
They are used as an ingredients in many food products as bakery
products, confectionary, mayonnaise and ice cream.
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13. Types of egg products:
•Whole eggs
•White
•Yolks
Different blends with or without non egg ingredients.
Egg to be processed are examined for freshness, and freedom of faults
(candling)
It carried out automatically and under strict sanitary conditions
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14. Basic steps for processing of egg products:
•Washing the shells
•Sanitizing the shells
•Breaking of eggs
•Separation of white and yolk if required
•Filtering to remove chalazae ,shell fragments …etc
•Mixing
•Stabilizing
•Pasteurizing 60- 62.8°C for 1-4 min
•Rapid cooling 4.4°C
•Chilling below 4°C, or freezing -17.8 to -20.5°C or drying
•Packaging
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15. Some techniques involved in production of egg products
1. Gelation control of frozen yolk:
The use of additives such as corn syrup, or salt prevents gelation
of frozen yolk and whole egg
2. Pasteurization
Food legislations require that all egg products to be pasteurized to
assure that they are free of pathogens ( salmonella)
It is carried out at 60 - 62.8°C for 1-4 min followed by rapid
cooling to 4.4°C
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16. 3. Addition of ingredients:
1. Carbohydrates such as corn syrup, or sugar help to
preserve the whipping properties of dried whole egg and
yolk products
2. Gums and starches improve the quality of products that
are precooked , frozen, thawed, and reheated
3. Salt or sugar may be added to control gelation of frozen
yolk products
4. Non- fat dried milk solid and vegetable oil are added
to egg mixes to improve texture and appearance
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17. 4. Stabilization of dried products
When glucose and other reducing sugar are added to dried egg
products, they react with the amino groups of proteins resulting
in :
Browning discoloration and development off- flavors during
storage. Therefore , prior to drying , glucose is removed from
the eggs using microbial or enzyme fermentation (a mixture of
glucose oxides and catalase enzymes).
Glucose removal improves the storage stability of dried
products
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18. Forms of egg products
1. Refrigerated liquid egg products:
After breakage of eggs, the contents are homogenized either as
whole egg or separated into white and yolk followed by
pasteurization and rapid cooling to below 4°C
They are widely used by the food service industry.
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19. They are transport directly from the breaking plant to the user
in insulated thermal tanks or in portable refrigerated vats
They must be maintained below 4°C
They should use as first in first out
Proper storage and handling is critical to prevent
microbial contamination
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20. 2. Frozen egg products:
After cooling to 4.4°C pasteurized
products are placed in metal container
and hold -17.8 to -20.5°C
Its forms:
• egg white
• egg yolk
• sugared yolk
• salted yolk
• whole eggs
• salted whole eggs
• whole eggs with added yolk
(fortified)
• whole eggs with yolks and syrup
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21. when frozen yolk is thawed gelation will appear . therefore, sugar,
corn syrup or salt 2-10% is blended
•to prevent gelation
• increase viscosity
•allow the product to become quite fluid and easy to handle when
thawed.
Storage and handling:
Frozen products have long shelf life when kept at -17.8°C or less.
It must be thawed in their unopened container under refrigeration or
under cold running water
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22. 3. dried egg product:
They are produced by spray drying, some egg white is
dried on trays to produce flake or granular form
Dried egg product are usually ingredient in food industry
,they are not sold directly to the consumer
Before egg white are dried , glucose is removed
(stabilization) this produce product with excellent
storage stability
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23. its forms:
• spray dried whole egg
• white solids
• instant egg white solids
• yolk solids
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24. The following may be added to dried products:
• whipping aids as sodium lauryl sulfate 0.1% to produce
dried egg white product with whipping stability
• non reducing carbohydrates such as glucose free corn
syrup, sucrose to preserve whipping property and improve
storage stability
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25. storage and handling:
* egg white solids when kept dry are stable during
storage even at room temp
* dried whole egg and egg solids should be kept cool at
less than 10°C to maintain quality
* once egg solids container opened , they should be
closed tightly to prevent contamination and absorption
of moisture
*** reconstituted egg should be used immediately
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26. 4. special egg products:
• chopped hard cooked, peeled egg, cryogenically frozen used in
salad bars in restaurants
• whole hard cooked, peeled eggs, plain or pickled eggs are
usually packed in citric acid with preservative or pickling solution
• frozed hard cooked rolls, or long eggs ( albumin is cooked
around a center core of egg yolk) cryogenically frozen used sliced
for salad
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27. labeling of egg products
• label must show common name
• ingredients must be listed in descending order
• nutrient composition per serving and its contribution
to the overall diet
• name , address of manufacture or distributer
• date of manufacture and expiry
• the net weight
• instruction of storage, handling, reconstitution…..
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28. Recommendation for safe storage and handling of egg products
To prevent microbial contamination ,instruction for handling and
storage provided by manufacturer should be followed
1. frozen products:
Frozen products have long shelf life when kept at -17.8°C or less
It must be thawed in their unopened container under refrigeration
or under cold running water
Don’t thaw on the counter
After thawing, don’t refreeze again
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29. 2. Liquid products:
They must be maintained below 4°C up to 7 days
Store opened container for not more than 3 days after opening
Don’t freeze opened cartons
3. dried egg product and egg white solids:
Store in a cool, dry place
Once container opened , they should be closed tightly and store
in the refrigerator
Reconstituted egg should be used immediately or kept in the
refrigerator and store that day
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30. Other uses of eggs (not in food)
1. Manufacture of vaccines:
eggs are used to propagate virus for different vaccines
2. Culture media:
m.o. grow better if small amount of egg yolk is added to media
3. Use of individual egg protein:
Egg white has numerous unique proteins
•lysozyme is separated from egg white using ion exchange resins as
antimicrobial agent and in some pharmaceutical preparations
•Avidin is separated along with lysozyme . Avidin- biotin technology
is used in various medical diagnostic applications such as
immunoassay, histopathology and gene probes
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31. 4. animal feeding:
Egg –by- products ( yolk and whole egg) made an excellent
nutritional ingredients for pet foods
egg shells from processing plants are often dried and fed to laying
hens as an excellent source of calcium and protein
5. cosmetics:
Eggs are often added to shampoos, soaps
6. pharmaceutical preparations:
Egg cholesterol is used in cosmetics by the pharmaceutical
industry
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