spoilage of eggs

1. SPOILAGE OF EGGS
Submitted by
Khushboo Bhagchandani
Bsc sem 6th

2. CONTENTS
• Composition of egg
• Contamination of egg
• Spoilages
• Bacterial spoilages
• Fungal spoilages
• Storage
• Preservation

3. COMPOSITION OF EGG
• An egg basically consists of three parts:
• a shell
• an egg white
• an egg yolk

4. The eggshell
The shell is built of 8-10,000 pores, which ensures that oxygen can penetrate and
CO2 and other gases can escape. The shell represents about 10 % of the weight of
the egg and consists mainly of calcium carbonate and calcium phosphate.
The egg white
The egg white represents approx. 60 % of the weight of the egg and consists of 88 %
water and 12 % dry matter, primarily protein.
The egg yolk
The yolk has a much lower water content than the egg white, just under 50 %. The
yolk represents about 28 % of the weight of the egg and consists of approx. 2/3 fat
and 1/3 protein. The fat content consists primarily of triglycerides, cholesterol, and the
phospholipid lecithin.

6. CONTAMINATION OF EGG
• Freshly laid eggs are sterile. Eggs can become contaminated from the
droppings of poultry through the laying process or from the environment
(e.g., contaminated poultry feed or bedding).
• Poultry may carry bacteria such as Salmonella that can contaminate the inside
of eggs before the shells are formed
• Shells can also be contaminated by Fecal matter from hen, cage or nest

7. BACTERIAL SPOILAGE OF EGGS
• Bacteria need to overcome the antibacterial
properties of albumen to cause the spoilage of
eggs
• Also they use protein complexes as the source of
nitrogen for there growth
• Bacterial spoilage is also called ROTS

8. GREEN ROT
• Green rot in eggs is widely recognized as one of the principal causes of loss in
the preservation of shell eggs. It arises from invasion of the shell contents by
strains of Pseudomonas fluorescens which multiply in the albumen and elaborate
the characteristic green pigment. The early stages of rotting cannot be detected in
the ordinary candling by white light, but the green pigment shows strong
fluorescence in ultra violet light. The yolk is also attacked and eventually the
entire contents break down into a semi liquid mass with a characteristic putrid
odour.

10. COLOURLESS ROT
• Caused by Pseudomonas, Acinetobacter
• Detected by candling.
• Yolk in the later stage disintegrates or shows a white
incrustation .
• Odour varies from scarely detectable to fruity

11. BLACK ROT
• Most commonly caused by a species Proteus, Pseudomonas,
aeromonas.
• Proteus melanvogens causes black colouration in yolk
• Caused when egg is stored in the temperature higher than the
ordinary
• Gas pressure develops in egg at high temperature
• Putrid Odour (hydrogen sulphide is evident)

13. PINK ROTS
• Less often caused by Pseudomonas
• They resemble coloured rots except for the pinkish
precipitation on the yolk and a pink colour in egg white.

14. FUNGAL SPOILAGE OF EGG
• Spoilage of egg by fungi goes through stages of mould
growth . There are 2 types
• Pin spot molding
• Fungal rotting
Penicillium, clodosporium, mucor, sporotrichum & Botrytis

16. PIN SPOT MOLDING
• Very early mould growith.
• Small compact colonies of the mould papers on the shell and
usually just inside it.
• Colour varies from the kind of mould
• Pencillium sp. Causes yellow, blue green spots inside the shell.
• Clodosporium sp. Causes dark green or black spots.
• Sporotrichum so. Gives Pink spots

17. FUNGAL ROTTING
• Final stage of spoilage.
• Mycellium of the mould has grown through The pores or
cracks in the egg.
• Jellying of egg white is seen.
• The hypae of the mould may weaken the yolk membrane
enough to cause the rupture. After this the growth is
stimulated by food realsed from the yolk

18. DEVELOPMENT OF FLAVOURS
• Mustiness may be developed In the eggs by bacteria
sometimes
• Growth of streptomyces produce earthy or musty flavours
that are absorbed by eggs.
• Fishy flavours are caused by strains of ecoli.

19. STORAGE
• Careful storage of edible eggs is extremely important, as an improperly handled egg
may contain elevated levels of Salmonella bacteria that may cause severe food
poisoning. In the US, eggs are washed. This cleans the shell, but erodes
its cuticle. The USDA thus recommends refrigerating eggs to prevent the growth
of Salmonella.
• Refrigeration also preserves the taste and texture, however, intact eggs (unwashed
and unbroken) may be left unrefrigerated for several months without spoiling. In
Europe, eggs are not usually washed, and the shells are dirtier, however the cuticle is
undamaged, and they do not require refrigeration. Ini the UK in particular, hens are
immunized against salmonella and generally, their eggs are safe for 21 days.

20. PRESERVATION
• The simplest method to preserve an egg is to treat it with salt. Salt draws water
out of bacteria and molds, which prevents their growth. The Chinese salted duck
egg is made by immersing duck eggs in brine, or coating them individually with a
paste of salt and mud or clay.
• Another method is to make pickled eggs, by boiling them first and immersing
them in a mixture of vinegar, salt, and spices, such as ginger or allspice.
Frequently, beetroot juice is added to impart a red color to the eggs.

21. Salted duck egg

22. Cooling:- It was done by holding eggs in refrigerator at 4-
5○C
Pasteurization:- The eggs were subjected to moist heat
(water bath) at 57°C for 15 min. and stored in refrigerator at
4-5○C.
Oiling:- A thin film of odorless, tasteless mineral oil sprayed
on eggs and stored at room temperature 25ºC.

23. THANK YOU.