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A Technical guide of Egg in Foods NAMRATHA KOLLU Copyright © 2012 Author Name All rights reserved

A Technical guide of
Egg in Foods

NAMRATHA KOLLU

Copyright © 2012 Author Name
All rights reserved.
ISBN:
ISBN-13:

DEDICATION

I dedicate this book to My Father, a retired Air Force sergeant and a poultry
farmer, who always told me what didn’t know will be filled by a book. And
whose impressive career advancement despite remedial technical skills
inspired me to believe that I was capable of authoring a book.

CONTENTS

Acknowledgments i
1 Introduction to Eggs 1 – 3
2 Definition and Structure of Egg 4 – 6
3 Classification of Eggs 7 – 10
4 Chemical Composition of Eggs 11-14
5 Evaluation of Quality of Eggs 15-26
6 Microbial Spoilage of Eggs 27-29
7 Preservation and Maintenance of Eggs 30-32
8 Functional Properties of Eggs 33-43
9 Egg Powder 44-46
10 Formulations 47-57

i
ACKNOWLEDGMENTS

I express my deepest thanks to Mr. Sivaram Prasad Borra, for taking part in
useful decision ; giving necessary advices and guidance and arranged all
facilities to make life easier. I choose this moment to acknowledge his
contribution gratefully.
It is my radiant sentiment to place on record my best regards, deepest sense
of gratitude to Mrs. Preethi Sagar, my teacher and my guide, Mrs. Sobha
Rani, my mother for their careful and precious guidance which were
extremely valuable for my study both theoretically and practically.
I perceive as this opportunity as a big milestone in my career development.
I will strive to use gained skills and knowledge in the best possible way, and
contribute some to the world of food science and technology. Hope to
continue cooperation with all of you in the future.

1

1 . INTRODUCTION TO EGGS

Eggs play an very important role in the human diet and nutrition as it is an
affordable nutrient rich food product. An egg contains highly digestible
proteins, lipids, minerals and vitamins.

Until 1988, Europe was the largest producer of eggs. It was surpassed by
Asia in early 1990s (IEC, Economic report -2014). The European
production volumes have been decreased due to the collapse of political
and economic systems in Russian Union and Eastern Europe.

Over the past 30 years, the egg production has grown to 152% due to the
rapidly increasing demand of the nutrition rich products and high protein
products in the developing countries. Asian egg production has seen an
increase by 388% (FAO Statistics).

Reference: FAO database ( http://faostat3.fao.org)

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2

The below table indicates the contribution of various countries in egg
production. China contributed to a whole of 39% of the worlds global egg
production.

Reference: FAO database ( http://faostat3.fao.org)

The major egg producing countries are China, US, India, Japan and Mexico.
The egg consumption in China is majorly as table eggs and only 1% of eggs
are broken and further processed. In US, 30% of the consumption is in the
form of processed eggs like liquid, frozen etc.,

In 2014, approximately 179 eggs per person were available globally for
consumption. The United States, a leader in both consumption and
production of eggs, saw its egg consumption rise since 2011 to a decade-
long high of 263.3 eggs consumed per person in 2014. In 2015, however,
the American Egg Board projects consumption will have fallen to 248.5
eggs per person annually. The decrease is majorly due to the increase in the
prices of eggs.

The per capita consumption of eggs in India is only 43 against the

A TECHNICAL GUIDE OF EGGS IN FOOD

3
prescribed consumption of 180 eggs per year per head by National Institute
of Nutrition. The less consumption is majorly due to the vegetarian
population and unorganized farming.

While the average consumption in other Asian countries like China and
Japan is 312 and 346 respectively. In Mexico, it sums up to 304 per person
per year.

Along with the food uses, eggs have an important share in the
pharmaceutical and nutrition industries for the extraction of the bio active
compounds like phospholipids, avidin etc., The non-food applications
include the utilization of egg shells in the fertilizer industry and chemical
industry as a source of calcium.

References:
1. FAO database ( http://faostat3.fao.org)
2. Hans-Wilhelm Windhorst, IEC Statistical Analyst Patterns of
European egg production and egg trade after the banning of
conventional cages in the EU
3. India’s egg consumption remains static
(https://timesofindia.indiatimes.com/business/india-
business/Indias-egg-consumption-remains-
static/articleshow/5112456.cms)

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2. DEFINITION AND STRUCTURE OF EGG

Definition of Egg:
According to science, egg is an organic vessel which holds an embryo. The
only difference being whether the egg is fertilized or unfertilized. The eggs
which are used for human consumption are unfertilized eggs. The eggs
which are fertilized by a sperm develop into living organisms in favorable
conditions.
Structure of Egg:

An egg basically consists of 3 parts.
? A shell
? An egg white
? An egg yolk

Shell:

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? The shell is made up of calcium carbonate and calcium phosphate.
? The shell is built of 8000-10000 pores, which ensures that oxygen
can penetrate and CO2 and other gases can escape.
? These pores are sealed with the calciferous protein keratin.
? The shell represents of 10% of weight of egg.
? The color of shell is majorly dependent on the breed.
? The shell consists of 3 layers.
? Outer cuticle made up of keratin , Middle spongy layer and Inner
mammary layer.

Shell membranes:
? Lying between the shell and egg albumen, there are two transparent
protein layers.
? These layers prevent the entry of bacteria into the egg.
? These layers are partly made up of keratin which is protein in hair.

Air cell:
? An air cell is formed when the contents of egg contracts after
cooling.
? The air cell usually rests between the outer and inner shell
membranes towards the larger end of the egg.
? As the age of the egg increases the size of the air cell increases.
This is due to considerable amount of moisture loss from the
contents of egg. Hence, the size of the air cell is used to determine
the freshness of egg.

Egg Albumen:
? The egg white is also known as albumen which originates from a
Latin word “albus” meaning white.
? Albumen constitutes about 66% of the liquid weight of egg.
? Four alternative layers of thick and thin albumen are present inside
the egg.

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? From the yolk outward, there are designated as inner thick or
chalaziferous white, the inner thin white, the outer thick white and
the outer thin white.
? As the egg ages the albumen tends to thin down because of the
change in its protein structure.
? Hence, it is used to determine the quality of egg. The fresh egg sits
upright when broken but the aged egg spreads out.

Chalazae:
? Ropy strands of egg white which holds the egg yolk in place in the
center of the egg albumen.
? The more prominent the chalazae, the fresher the egg.

Egg yolk:
? The yolk or the yellow portion of the egg makes up to 34% of
liquid weight of egg.
? It contains all the fat in the egg.
? In fertilized eggs, the yolk is the site of embryo development.

Vitelline membrane:
? It is the clear casing that holds the egg yolk.
Germinal Disc:
? The channel leading to the center of the yolk.
? The germinal disc is slightly noticeable as a slight depression on the
surface of the egg yolk.
? If an egg is fertilized, the sperm passes through the germinal disc to
the center of the yolk and an embryo is formed.

References:
1. American Egg Board (www.aeg.org)
2. Stadelman, W.J. & Cotterill, O.T. 1986. Egg science and
technology, 3rd edition. Westport, CT, AVI.
3. FAO -Egg Production

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3. CLASSIFICATION OF EGGS

The classification of eggs can be based on the following:
? Source of egg
? Relative amount of yolk
? Farm and Feed
? Grades
? Sizes

1. Based on the Source of Eggs:
The eggs are classified based on the source bird. The below table
indicates the classification and their characteristics.

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2. Based on relative amount of yolk:
The eggs are classified based on the quantity of yolk. The below
table indicates the classification and their characteristics.
Egg Type Characteristic Representative animal
Alecithal Almost without yolk Placental mammals
Microlecithal Small amount of yolk Echinoderms, amphioxus, marsupials
Mesolecithal
Moderate amount of
yolk Lung-fishes, frogs and toads
Macrolecithal
Very large amount of
yolk Sharks, bony fishes, reptiles, birds, insects

3. Based on the farm and feed:
The eggs are classified based on the farming method employed and
the feed being used for enhancement of particular nutrient. The
below table indicated the classification and their characteristics.

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9
4. Based on Grades:
The eggs are named after particular grades which are formed based
on set quality parameters. The below table indicates the same.

5. Based on sizes:
There are different names for eggs based on US and EU standards.
The below table indicate the same.

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References:
1. American Egg Board (www.aeg.org)
2. Stadelman, W.J. & Cotterill, O.T. 1986. Egg science and
technology, 3rd edition. Westport, CT, AVI.
3. FAO -Egg Production
4. EMBRYOLOGY- LECTURE NOTES-I
5. USDA – Grading Manual of Eggs

11

4. CHEMICAL COMPOSITION OF EGGS

Avian eggs are an excellent source of nutrients, particularly high quality
proteins, lipids, minerals and vitamins. An egg is composed of
approximately 75% water, 12% proteins , 12% lipids and less than 1 %
carbohydrates and minerals.

As mentioned and discussed earlier, an egg consists of 10% shell, 59%
albumen and 31% yolk.

The chemical composition of the egg is already discussed in the Chapter -1.

The following table indicates the composition of egg and its components:

Component Water% Protein% Fat % Ash%
Whole Egg 65.5 11.8 11 11.7
Egg White 88 11 0.2 0.8
Egg Yolk 48 17.5 32.5 2

Component
Calcium
Carbonate%
Calcium
Phosphate%
Magnesium
Phosphate%
Organic
matter%
Shell 94 1 1 4

Chemical composition of Egg albumen:

The major constituents of albumen are water and protein followed by
carbohydrates that exist in free form , usually as glucose, or forming
complexes with protein forming glycoproteins. The albumen is also
composed of lipid and ash in minor quantities.
Albumen may be regarded as a protein system consisting of microscopic
fibers in a solution of numerous globular proteins. These are made up of
ovomucin fibers.

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Egg albumen is made up of the following:

Protein
Relative amount in
albumen % Characteristic
Ovalbumin 54 Phospoglycoprotein
Conalbumin 13 Binds metals especially iron
Ovomucoid 11 Inhibits trypsin
Lysozyme(Globulin
G1,G2,G3) 10 Lyses some bacteria
Ovomucin 1.5 Sialoprotein
Flavoprotein 0.8 Binds riboflavin
Ovoinhibitor 0.1 Inhibits several proteases
Avidin 0.05 Binds biotin

? Ovalbumin, a phospoglycoprotein with a molecular weight of 45
KDa and an isoelectric point of 4.5, is the most abundant protein
in egg white.
? It is the only portion of the egg white that contains free sulphydryl
groups and is a major source of amino acids for the embryo.
? Ovotransferrin, accounting for about 13% of egg white proteins, is
a glycoprotein with a molecular weight of 75KDa and an isoelectric
point of 6.
? It is a disulphide-rich single chain glycoprotein and belongs to
transferrin family.
? It is also called as Conalbumin and as a part of transferrin family, it
is able to bind to iron, and is known for antimicrobial, antifungal
and antiviral activities.
? Ovomucoid, representing 11% of total albumen proteins, is a
thermostable glycoprotein and the dominant egg allergen.
? It belongs to Kazal Family of protease inhibitors, with a molecular
weight of 28 KDa and an isoelectric point of 4.1.
? It inhibits absorption of trypsin.
? Ovomucin is a sulfated glycoprotein that contributes to the gel like
structure of the thick white layer, forming flexible fibers.
? It is composed of two sub units : alpha-ovomucin, with a molecular
weight of 254 KDa and beta-ovomucin, with a molecular weight of
400-610 KDa.
? Ovomucin represents 1.5% of total egg albumen and its iso electric
point is about 4.5-5.0.

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13
? Lysozyme is an enzyme with a molecular weight of 14.3 KDa and
an iso electric point of 5.5; it accounts for 10% of total egg white
and possesses bacteriostatic, bacteriolytic and bactericidal activity.
? Ovoglobulins, consists of two proteins, G2 and G3, with molecular
weights between 30 and 45 KDa and an iso electric point of 4.0.
? These proteins are known for their excellent foaming and beating
properties.
? Ovoinhibitor is capable of inhibiting trypsin, chymotrypsin as well
as fungal and bacterial proteases.
? Other components, including avidin, cystatin, ovostatin etc., and
minor levels of carbohydrates, minerals and lipids.

Chemical composition of Egg Yolk:

Egg Yolk represents 31% of the total egg white. It is composed mainly of
48% water ,17.5% proteins, 32.5% lipids, 1.7% minerals and 0.3%
carbohydrates.
? In dry matter, egg yolk is composed of 68% low density lipo
protein (LDL), 16% high density lipoprotein (HDL), 10% globular
proteins (livetins), 4% phosphoprotein (phosvitin), and 2% minor
proteins.
? Lipids represent about 65% and the lipid to protein ratio is about 2
to 1.
? The egg yolk protein consists of apovitellenin, phospovitin, alpha
and beta lipovitellin apoproteins, serum albumin, and glycoprotein
and traces of biotin binding protein.
? Lipids are found in the form of lipoproteins and usually are
composed of 62% triglycerides, 33% phospholipids and less than
5% cholesterol.
? The yellowish color of egg yolk is due to presence of carotenoids,
representing about 1% of the lipids, mainly carotene and
xanthophylls (lutein, cryptoxanthin and zeaxanthin).

References:
1. Burley RW, Vadehra DV (eds) (1989) The Avian Egg: Chemistry
and Biology. New York: Wiley.
2. Cunningham FE, Proctor V A, Goetsch SJ (1991) Egg white

NAMRATHA KOLLU
14
lysozyme as a food preservative: an overview. World’s Poultry
Science Journal 47: 141-163.
3. Ibrahim HR (2000) Ovotransferrin. In: Naidu AS (ed) Natural
Food Antimicrobial Systems. Boca Raton, FL: CRC Press pp 211-
226.
4. Li Chan E, Kim HO (2008) Structure and chemical composition of
eggs, In: Mine Y (ed) Egg Bioscience and Biotechnology. New
Jersey : John Wiley, pp. 1-65.

15

5. EVALUATION OF QUALITY OF EGGS

Quality has been defined by Kramer (1951) as the properties of any given
food that have an influence on the acceptance or rejection of this particular
food by the consumer. Egg quality is a general term which is used to
indicate the internal and external characteristics of egg.

Externally quality is majorly focused on the egg shell, shell cleanliness,
texture and shape. The internal qualities of the egg refers to the albumen
cleanliness, structure and viscosity , size of the air cell, yolk stability and
yolk shape.

Grading generally involves the sorting of products according to quality, size,
weight and other factors that determine the value of the product. The
grading quality of shell eggs is very important as the eggs are moved across
the districts and states. Grading quality helps in the establishment of the
uniform quality grades.

Grading aids orderly marketing by reducing waste, confusion and
uncertainty with respect to the quality values.

The different advantages of determining the egg quality standards are as
follows:
? Impartial grading that eliminates the need for the personal
inspection of the eggs by sellers, buyers and other interested
people.
? Pooling of lots of comparable quality.
? Development of improved quality at produce level through buying
on grade programs.
? Market price reporting in terms understood by all the parties.
? Negotiations of loans on generally accepted quality specifications.
? A basis for settling disputes involving quality.
? A basis for paying damage claims.
? A standard upon which advertising may be used.
? A uniform basis for establishing brand names.
? Establishment of buying guides for consumers.

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Quality factors of eggs are divided into two general groups.

1. Interior quality factors which involve the contents of eggs.
2. Exterior quality factors which involve the direct examination of an
egg.

Egg quality decline:

Newly laid egg vs aged egg:

Ref: Egg Grading manual

Evaluation of Egg quality

Some important quality characteristics are

1. Color of shell
2. Shell porosity
3. Shell strength
4. Albumin condition
5. Yolk
6. Presence of blood and meat spots
7. Nutritive value
8. Flavor
9. Cleanliness
10. Grading of eggs

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Shell color:

Visual examination and Automated machines for sorting of eggs are used to
detect soundness of shell color. The device grades egg automatically based
on percentage of reflectance.

Shell Porosity:

Shell pores are the channels of gas and water vapor exchange between egg
contents and outer atmosphere which helps in maintaining good internal
quality.

Low porosity of eggs is better for table eggs because it allows less loss of
moisture during storage.

Methods of measuring shell porosity are many and could be divided into 3
groups-
a) By direct counting of pores
b) By measuring weight loss under standard conditions of temperature and
humidity.
c) By measuring rate of liquid flow and gas under pressure

Shell strength:

It refers to the ability of the shell to retain its soundness during transit from
farm to the consumer. There are direct and indirect methods to measure
shell strength.

Indirect methods include measuring shell thickness, specific gravity method
and by measuring weight/unit area.

Direct measurement

a) Crushing: It is determined by using metal rods to crush placing the egg
on a metal plate. Increase in load may be correlated to shell fracture.

b) Piercing strength: Determined by using a steel needle in place of metal
rod or metal plate

c) Impact method: A falling ball can be used to determine breaking

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strength .The force of impact can be calculated by knowing the distance of
free ball and weight of ball.

Force of impact = Ht x Wt of ball

Ht – Height from which the ball has been dropped
Wt – Weight of the ball

Physical state of Albumen:

On storage the integrity of albumin structure is lost ,as a result albumin
spreads thinly when broken on a cooking surface.

The quality of egg albumin is measured by measuring Albumin index,
Haugh’s unit

Haugh’s unit = 100 log (H+7.57- 1.7W 0.37)

H.U is the function of height of thick albumin and weight of the egg.

Measurement of height of thick albumin is done by using micrometer. H.U
varies with storage – 82 at farm; 77 for whole sale; 60 for retail. For an egg
of poor quality H.U ranges from 36-60 while for a egg of good quality HU
is 72.

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Viscosity:

Viscosity of egg albumin is measured by using Viscometer. Visual scoring
of egg white is scored against standard charts like Van wagnen chart .This
chart facilitates a scoring from 1-5.One refers to highest quality and 5 refers
to lowest quality.

Albumin Area Index:

It is the ratio of weight the albumin and width of the albumin.

White index Measurement of height of thickest portion of white divided by
diameter of an egg.

Firmness of egg white is correlated with albumin quality Length of storage
and environmental conditions. Factors such as incorrect temperature, RH,
increase in loss of CO2 from the egg which is governed by length of
storage.

On storage the integrity of albumin structure is lost and as a result albumin
spreads thinly when broken on a cooking surface.

Yolk quality

The important yolk characteristics are color, spherical shape and strength of
vitelline membrane.

a)Color : Commonly measured by comparing against standard colored
charts like Roche Color chart which is most commonly used by USDA.

b)Spherical nature: It is assessed by yolk index with or without separation
from albumin

Yolk index= Ht of yolk/width of yolk

c)Strength of Vitelline membrane: It refers to the ability of vitelline
membrane to withstand rupture during egg breaking operation. This is
measured by capillary tube.

NAMRATHA KOLLU
20
Ref: Egg grading Manual

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NAMRATHA KOLLU
22
Ref:aeb.org
Terms descriptive of the egg quality
Shell:
1. Clean :
? Free from foreign material, free from stains / dis coloration
? Considered clean if it has specks, stains not enough to detect.
? Eggs that show traces of processing oil on the shell are clean
2. Dirty:
? Unbroken, dirty with foreign material adhering to its surface.
? Prominent stains (1/32 of the surface if localized and 1/16 of the
shell surface) if scattered.
3. Practically Normal(AA/A)
? Usual shape, sound and free from thin spots.
? Ridges and rough area(not affecting shape and strength).
? Free from spots
4. Abnormal
? Unusual/irregular in shape.
? Faulty in soundness/strength.
? Pronounced ridges and thin spots
Air cell:
1. Depth of Air cell: The depth of air cell is the distance from its top to its
bottom when the egg is held with the air cell upwards

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23
2. Free Air cell: Air cell that moves freely towards the upper most point in
the egg as egg is rotated slowly.
3. Bubbly Air cell: A ruptured air cell resulting in one or more small
separate air bubbles usually floating beneath the main air cell.

Terms descriptive of the egg white:
1. Clear : White free from discoloration or any foreign bodies floating in it.
2. Firm (AA) : Thick and viscous white with yolk outline being slightly
defined as it is twirled. Haugh’s (72)Unit when measured at a temperature
of an egg between 7.2-10.80C.
3. Reasonably firm (A): Less thick and viscous but with a well defined
yolk outline when twirled. Haugh’s unit ranges from 60-72 at a temperature
between 7.2-10.8 degree centigrade.
4. Weak ; Watery (B): Weak and watery thin white with the weak yolk
outline and comes in contact with the shell.
5. Blood spots or meat spots (B): Blood spot should not be more than
1/8 th inch. More larger or shows diffusion of blood into white usually
classified as loss.
6. Blood white: Egg with diffused blood in white and considered as loss.

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24

Terms descriptive of yolk:
1. Outline slightly defined (AA): Indistinct out line and appears to
blend on twirling. 2
2. Outline fairly well defined(A): Distinct outline and do not blend
easily
3. Enlarged and flattened: Yolk appears flattened and flat.
4. Practically free from defects (AA/A quality): No germ
development and may show slight defects on surface.
5. Blood due to germ development: Seen in fertile egg and also
appears as blood rings. Usually they are termed as inedible eggs
General Terms:
Loss: Inedible, smashed, broken, leaking and often contaminated eggs are
kept under this category.
Inedible: Eggs with Black rots, Yellow rots, Blood rings.
Leaker: Exudation of egg contents through the broken egg shell.

Determination of Interior Quality of Eggs by Hand Candling:
Hand candling is used very little used after the present commercial grading
operations has come in. Candling is the process of holding a strong light
above or below the egg to observe the embryo. A candling lamp consists of
a strong electric bulb covered by a plastic or aluminium container that has a
handle and an aperture. The egg is placed against this aperture and
illuminated by the light. If you do not have a candling lamp, improvise. Try
using a torch.
Hand Candling Booth:

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25
A hand candling booth should be 6ft wide, 4ft deep and 7ft high. It should
be a closed room so that the egg can be examined under light.

In determining interior quality by hand candling, it is customary to hold two
eggs in each hand, supporting one egg by the tips of the thumb and index

NAMRATHA KOLLU
26
finger and holding the other against the palm with the other fingers. The
small ends of the eggs should point toward the palm of the hand (fig. 49).
After one egg in the hand has been candled, it is shifted back in a rotating
motion to the palm of the hand and the second egg is brought into candling
position. The eggs are viewed alternately before the light.
The uppermost egg in one hand is examined first, then the uppermost egg
in the other hand, and this procedure is repeated after the position of the
eggs in each hand has been shifted. After the first egg is candled and the
hand is dropped slightly back and downward, the third and fourth fingers
are relaxed, letting the uncandled egg roll downward slightly.
At the same time, the thumb and index and second fingers guide the
candled egg into the palm of the hand. The third and little fingers then roll
the uncandled egg into candling position between the thumb and index
finger; meanwhile the little finger (fourth) and third finger hold the candled
egg in the palm. The position of the egg is changed in one hand while one
of the eggs held in the other hand is being candled. During this finger-to-
palm rotation, proficient candlers carefully conduct the “belling” process to
detect “blind checks.
In order to obtain a proper view of the egg while candling, it is necessary to
have the contents spinning within the shell at the time of viewing. This can
be achieved in one smooth motion when the two eggs in the one hand are
being rotated and moved toward the aperture in the candling light. The
contents of the egg will be set in motion by a movement of hand and wrist
in an arc of about 180° (3.06 rad).
Stopping the hand motion at the end of the arc without moving the arm or
body permits the contents to spin within the shell. The long axis of the egg
should be at about a 45° (0.76 rad) angle to the candling aperture. The
thumb and index finger should be on opposite sides of the shell without
obstructing the grader’s view.
References:
1. Egg Grading Manual. Agricultuyre Handbook No. 75, revised
(1983). Agricultural Marketing Service. Poultry Division. USDA,
Washington D.C. 20402

27

6. MICROBIAL SPOILAGE IN EGGS

It was widely believed in nineteenth century that contents of fresh eggs
were always sterile. Studies conducted afterwards revealed that
microorganisms can gain entry into the egg congenitally. However, most of
the contaminants of eggs are of extragenital origin and come in contact with
egg shell at oviposition from the dust, soil and faecal matter adhered to the
nesting material. Since the cuticle and pores of the egg shell are moist at
this stage, the possibility of invasion of the shell by some contaminants
through a few pores cannot be ruled out. The microorganisms on the shell
surface usually belong to a mixed group, but those causing spoilage of egg
(generally called rot ) are gram-negative in nature which have very simple
nutritional requirements.

The microorganisms have to pass through a series of in-built
physicochemical barriers in the egg—the shell, the shell membranes, the
albumen before reaching the yolk where they could easily multiply
causing rot.

The mechanism of microbial spoilage can thus, be divided into three serial
steps:
1. Penetration of microorganisms through the egg shell and shell
membranes.
2. Colonization of microorganisms on the shell membrane.
3. Overpowering of the antibacterial factors present in the albumen.

Penetration of Microorganisms through the Egg Shell and Shell Membranes

Egg shell acquires a diverse microflora at the time of oviposition. Under
normal conditions of handling and storage, shell gets dried soon and most
of these microorganisms fail to survive. An egg shell contains more than
17000 pores. However, only ten to twelve pores allow the microorganisms
to pass through. The microorganisms either succeed in when the egg
contents contract on cooling or gain entry due to capillary action through
pore canals when the shell surface is moist. The role of microorganisms
remain passive in both situations. It is due to capillary action that incidence
of rotting are comparatively high in washed eggs which have been subjected
to dry abrasion. The cuticular plugs on the pore canals are opened during
the process of abrasion of eggs.

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28
After gaining entry through the shell pores, microorganisms come across
shell membranes. These membranes act as bacterial filters and offer
maximum resistance to the offending organisms which have succeeded in
penetrating the shell. Some researchers believe that membrane lysozyme
also has a limited role.

Mold may also cause rot in eggs under humid storage conditions. In
such case shell is generally covered with mycelium (whisker) and hyphae
penetrate the pores to reach shell membranes.

Colonization of Microorganisms on the Shell Membrane:

Once the microorganisms have an access to shell membrane, they are able
to multiply and form colonies. However, the colonization is not instant. In
the early stages, there is preferential selection of gram negative organisms
having low iron requirement from the initial population dominated by gram
positive organisms which have high iron requirement. Thus initially there is
a decline in the microbial numbers. In the later stages, multiplication of
organisms takes place at a faster rate because by this time albumen becomes
heavily infected. The pH of egg contents move towards neutrality and yolk
comes in contact with inner shell membrane.

Overpowering the Antibacterial Factors Present in the Albumen

Egg white or albumen provides an unfavorable medium for microbial
growth because of the defensive role played by many of its component
proteins which have been listed under composition of albumen. The role
played by lysozyme and conalbumen is particularly important. Lysozyme of
albumen cause lysis of mucopeptide rich cell wall of gram positive
organisms. This enzyme does not affect the complex cell wall of gram
negative bacteria having coating of lipoprotein and lipopolysaccharide over
mucopeptide.

Conalbumen which is uniformly distributed and constitutes more than
10% of albumen chelates iron and make it unavailable to the bacteria.
Conalbumen is the principal antimicrobial factor present in the egg and its
inhibitory action is more on gram positive as compared to gram negative
organisms. This inhibition definitely delays the spoilage of eggs to some
extent. However, as yolk contents migrate into albumen or gen mixed,
multiplication of organism is very fast which results in the rotting of eggs.

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29
Some general type of rots may be summarized as follows:

Type of rot Changes in egg Organisms
Green rot Albumen becomes green
Pseudomonas
Fluorescens
Black rot (Type 1)
Blackening of yolk with
“faecal odor” , Proteus sp.
Black rot (Type 2)
Green colored albumen
but yolk is black with
“cabbage odor” Pseudomonas sp.
Red rot
Albumen stained red
throughout Serratia sp.
Fungal rot
Yolk surrounded by
custard like material Pink
spots on egg contents
Black spots on contents
Yellow or green spots on
contents
Sporotrichium,
Cladosporium, Penicillium

Besides rots, eggs may develop various types of off odor due to bacteria
without any apparent signs of spoilage. These off odors may be musty or
earthy (achromobacter sp), hay like (Enterobacter sp), fishy (E.coli) or that
of cabbage water (Pseudomonas sp.)

References:
Egg Grading Manual. Agriculture Handbook No. 75, revised (1983).
Agricultural Marketing Service. Poultry Division. USDA, Washington D.C.
20402

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7. PRESERVATION AND MAINTANANCE OF
EGGS

A freshly laid egg can be assumed to have a highest quality. Since egg is full
of essential nutrients, deteriorative changes soon start taking place which
may pose a danger to the excellent sensory attributes of this nourishing and
satisfying food item. Cleanliness and soundness of shell is the first step to
assure the quality of egg to the consumers. The shell quality deficiencies
mostly relate to the production practices adopted at the farm. Proper
handling of eggs can delay the decline in the quality. Following precautions
should be taken during handling of eggs:

i. Eggs should be collected 3 to 4 times per day. This will result in less dirty
eggs and fewer breakages.
ii. After collection, eggs should be shifted to holding room maintained at a
temperature of about 150C and 70 to 80% RH at least for 12 hours.
iii. Eggs should be properly packed in filler flats with broad end up. Bulk
packing should be done in fiber board cartons.
iv. Eggs should be rapidly moved through the marketing channel so as to
reduce the period between production and consumption.

All preservation methods for shell eggs have been designed to retard one or
more of the following physic-chemical alterations which lower the quality
of egg as it ages:

i. As the surface of egg dries, the keratin cuticle shrinks and size of shell
pores increases rendering it easier for gases and microorganisms to pass in
and out of the shell.
ii. As the warm egg contents also contract, resulting in the formation of air
cell.
iii. The breakdown of carbonic acid causing loss of carbon dioxide from
the albumen is rapid during the first few hours after an egg is laid. The
alkaline pH acts on the mucin fibers to disturb the thick gel of albumen
making it thin or watery.
iv. As the egg ages, water migrates from the albumen to the yolk which may
overstretch, weaken or even rupture the vitelline membrane.

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31
Following preservation methods are employed to maintain the quality of
shell eggs:

Egg Cleaning

Earlier, it was a general practice to dry-clean dirty egg shells by abrasive
mounting on a mechanical wheel. This practice has now become obsolete
because it weakens the shell. These days washing in warm water containing
a detergent sanitizer is an effective way of cleaning the eggs with dirty
shells. A temperature difference of 10-15?C between eggs and wash water
is ideal, otherwise there may be problem of crack shells. Besides, eggs
should not be immersed in warm water for more than 3-4 minutes. After
washing, the eggs should be dried promptly. Wash water should be
changed after washing every five to six baskets of eggs. It should be
emphasized that only dirty eggs are subjected to washing. It not only
reduces the microbial load on the egg shell surface but also improves the
appearance and consumer appeal.

Oil Treatment

Oil coating spay of eggs has become very popular for short term storage of
this commodity. Coating oil forms a thin film on the surface of the shell
sealing the pores. It should be done as early as possible, preferably within
first few hours after laying of eggs because loss of CO2 is more during this
period and evaporation of moisture is also more during the first few days.
Egg coating is done by dipping the eggs in the groundnut oil whereas for oil
spray, the eggs are arranged in the filler flats with their broad end up. If the
eggs need washing, oil coating should be done after washing. It is
important to drain out excess oil before packaging. The temperature of oil
should be in range of 15 to 30?C for ideal results. Oil treatment safeguards
the quality of albumen for at least 7 days because it effectively seals the shell
pores.

Cold Storage

This method of preservation is suitable for long tern storage of clean eggs
in the main laying season and abundant availability. The temperature of
cold store is maintained at 0?C (320F) and relative humidity between 80 to
85 per cent. An anteroom with intermediate temperature is generally
provided to check condensation of water vapor on the eggs during removal.
Use of new egg packing trays are advised for cold storage. Like all other
animal products, eggs also pick up strong odor, so the same cold store

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32
cannot be used for storing onion, garlic or any other commodity with
strong odor. The quality of shell eggs can be maintained for about 6
months in a cold storage. Oil coating of eggs prior to cold storage can
further enhance their keeping quality. Such eggs could keep well at 14?C
and 90% RH for a period of 8 months.

Thermostabilization :

This preservation method involves stabilization of albumen quality by
holding the eggs in an oil bath maintained at 55?C for 15 minutes or 58?C
for 10 minutes. This process brings about coagulation of thin albumen just
below the shell membranes, thereby blocking the passage of air and
moisture. In addition, oil coating of shell pores also takes place. Thus
keeping quality of eggs is maintained for sometimes and thinning of egg
white is retarded. Alternatively, eggs are immersed in hot water at 71?C for
2 to 3 seconds. In this flash heat treatment, bacteria present on the surface
of the shell are destroyed and a thin film of albumen just below the shell
membrane is coagulated sealing the egg shell from inside.

Immersion in Liquids :

Under rural conditions, lime-water or water –glass immersion are most
useful. In lime-water treatment, a liter of boiling water is added to 1 kg of
quick lime and allowed to cool. Now 5 liters of water and 250g of table salt
are added to it. The solution is strained through a fine cloth when the
mixture settles down. Eggs are dipped in the clear fluid overnight and then
dried at room temperature. In this process, an additional thin film of
calcium carbonate is deposited on the egg shell and seals the pores. Such
eggs can be stored for a month at ambient temperature. In water-glass
treatment, one part of sodium silicate is mixed in 10 parts of water and eggs
are dipped overnight. In this process, a thin precipitate of silica is deposited
on the egg shell and partially seals the pores. It is clear from the above
discussion that eggs should be collected frequently, held initially at low
temperature and then a suitable preservation method be employed to
maintain its keeping quality for anticipated consumer acceptance.

References:

1. Li Chan E, Kim HO (2008) Structure and chemical composition of
eggs, In: Mine Y (ed) Egg Bioscience and Biotechnology. New
Jersey : John Wiley, pp. 1-65.

33

8. FUNCTIONAL PROPERTIES OF EGG

The main roles of functional properties of whole egg are stabilization of
emulsion, foamability and build up firm gels. Whole egg is also used as
colorants. These natural properties of whole egg are useful in bakery foods,
bakery mixes, mayonnaise and salad dressings, confections, ice cream,
pastas and many convenience.

The following are the functional properties of eggs:
1. Adhesion
2. Aeration/ Foaming
3. Binding
4. Browning/color
5. Clarification
6. Coagulation or thickening
7. Coating
8. Flavor
9. Stabilization
10. Leavening
11. Fortification
12. Humectant
13. Textural properties
14. pH stability
15. Whipping ability

Adhesion:

The proteins in egg products, specifically in the whites, assist with adhesion
and ingredient binding. When they are heated or exposed to acid, they
coagulate, causing the egg product to change from a liquid to a semisolid or
sold. When the proteins solidify, they function as an adhesive, connecting
ingredients or food components with each other.

Aeration:

Certain food formulations, particularly in baking, rely on aeration to
provide proper product structure. Aeration can be achieved in several ways
including biological (yeast), chemical (baking soda), mechanical (methods of
mixing certain ingredients or the batter through whipping or beating),

NAMRATHA KOLLU
34
physical (lamination or steam), or a combination of those methods. Each is
designed to introduce a gas, such as air, into a liquid or viscous solution.

When air is incorporated into a liquid or viscous solution, the solution traps
the air bubbles, forming a foam. If proteins stabilize the foam, it leavens a
food, increasing its height and reducing its density. Eggs supply aeration to
baking applications through the mechanical method, with the viscosity of all
egg products ideal for incorporating air cells during the whipping or beating
process.
As whipping or beating progresses, air bubbles decrease in size and increase
in number, surrounded by egg proteins. Liquid egg products have low air-
liquid interfacial tension, therefore when eggs are beaten or whipped, the
proteins denature, or simply, they unfold. This exposes two oppositely
charged ends of the protein molecule: the hydrophobic, or water hating
end, and the hydrophilic or water loving end. The proteins line up between
the air and water, securing the air bubbles with their hydrophilic end and
pointing the hydrophobic end in the other direction. During baking, these
proteins bond with each other, forming a delicate, yet reinforced network.
Egg whites form foams greater in volume than yolks due to the unique
proteins found in the white. In fact, even though the term foam technically
refers to any system where there are entrapped air bubbles, in the food
industry, when discussing egg products, the term tends to be exclusive to
egg white foams. This is because egg whites, unlike any other natural food
ingredient, are able to create the largest possible food foam, six to eight
times greater in volume than unwhipped, non-aerated liquid egg white.
The egg white proteins that enable such impressive foaming are ovalbumin
and ovomucin. Ovalbumin is responsible for original foam volume when
egg whites are whipped, while ovomucin holds onto the air bubbles during
heating and has elastic qualities that allow the protein to stretch as the air
bubbles enlarge.
This foaming ability of egg white finds uses in multiple baking applications,
particularly angel food cake, which relies on the aerating power of egg white
for its characteristic texture, height, appearance and cell structure. Certain
confections, such as nougat candies, rely on proper aeration for height,
appearance and texture, which can suffer when egg white is removed.
Increasing the acidity of egg whites helps stabilize the foam by loosening
the protein structure, keeping the foam elastic and stable enough to entrap
air cells, and allowing them to expand when heated, resulting in better
volume.

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35
In certain applications whole eggs and egg yolks also increase the volume of
foods through the process of aeration, including some baked goods and
dairy desserts such as ice cream and custard.
Binding:
The binding property supplied by eggs to food manufacturers proves
valuable in numerous applications ranging from appetizers through
desserts. Binding may be related to its ability to coagulate and form gels, but
in essence, it holds other ingredients together. This binding action mainly
benefits product structure, texture and mouthfeel.
In meat or fish formulations for example, egg proteins react synergistically
with these other proteins to help bind ingredients together for greater
product integrity. One reference states that the synergy between fish and
egg white proteins makes egg white powder an “indispensable ingredient”
in surimi manufacturing, binding the ingredients together through gelling or
coagulation. Egg products form gels easily within certain meat matrices to
hold together meat patties and sausages.
In surimi specifically, another study states that when testing protease
inhibitors, egg whites provide a better effect than other proteins. It went on
to say that when creating a surimi gel with egg white, the gel formed a
network with fewer cavities due to the “effective cross-linking and protein
aggregation” between the egg white and fish proteins, that the gel exhibited
good physical properties, and the egg white provided high gel strength.
In prepared foods, the binding action exhibited by egg ingredients, whether
through gelation or coagulation, prevents products from crumbing or losing
their shape, maintaining a desirable texture and form. When binding
breading to foods, research suggests that batter with protein levels of 10 to
15 percent tends to be the most effective binding agent.
In baked goods, eggs bind other ingredients together naturally, aiding with
product structure, texture, form and appearance. Proper binding also lends
baked goods a tender crumb and can contribute to a light, airy texture.

Browning/color

Egg products can contribute to product color in two ways; browning on the
product exterior in the case of baked goods, or the product itself such as
coloring mayonnaise or muffin interiors.

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The proteins within eggs can participate in the Maillard reaction when
exposed to heat, producing a desirable brown color. The Maillard reaction
is responsible for the golden crust of baked products such as yellow batter
cake, meat browning and the dark color of roasted coffee.
In addition, egg yolk contributes rich color to various foods via
xanthophyll, a carotenoid with a yellow-orange pigment that gives the yolk
its characteristic color. Egg yolks impart a rich yellow color to cakes and are
often used to fortify whole egg products within formulations to yield a
more intense color or increased emulsifying action. The pleasing color that
eggs impart to baked foods has long been accepted as a mark of superior
quality.
The beautiful yellow/orange hues of egg yolk, or the xanthophyll it
contains, add “richness in color,” which aids perceived quality and
freshness for products from mayonnaise to baking applications. The
xanthophyll content, the major pigment in egg yolk, is stable under most
conditions encountered in food processing.
While color is an important factor in food product development, it is “rare
for eggs to be used as an ingredient in food products for their color
contribution alone,” says one author, since eggs possess multiple functional
benefits beyond this coloring ability.

Clarification:

Eggs, especially whites, can clarify or clear various fluid products, including
consommé, broth and even wine. When the fluid is heated, added egg white
coagulates, capturing and holding minute particles. Depending on the size
and weight of the encased particles, the cooked whites may sink to the
bottom, allowing the clarified mixture to be carefully poured off.
Sometimes the whites may bubble to the top where they are skimmed off,
resulting in a crystal-clear product.

Coagulation or thickening:

Coagulation indicates a change from a fluid to a solid or semisolid (gel)
state. The success of many cooked foods depends on the coagulative
properties of proteins, particularly the irreversible coagulative properties of
egg proteins. The property is one of the egg’s most important functional
benefits for food formulators, as it enables eggs to bind foods together,
thicken applications, such as custards, omelets and puddings or positively
benefit the crumb and structure of baked goods, such as cakes and cookies.

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37
In cookie formulations, for example, egg proteins permeate the dough and
coagulate “contributing rigidity to the crumb and assisting the gluten to
hold the volume attained.” In a custard or pudding, this coagulative
property is responsible for the custard texture and mouthfeel. As one
source says, “Eggs are the main thickener in most custard and the yolks
make them smooth and rich.” Starch is often added to custard to slow the
process of coagulation to help prevent overcooking the mixture.
Egg proteins denature and coagulate over a wide temperature range.
Natural protein consists of complex, folded and coiled individual molecules.
Loose bonds across the folds and coils hold each protein molecule in a
tight, separate unit. These bonds can be disrupted when exposed to heat or
acid, or by physical means such as whipping, causing the protein to
denature.
Coagulation or gelation in eggs can be achieved by several different means,
including heat (protein denaturation), mechanical (beating or chipping),
sugar (raises the temperature for coagulation), acids (decrease temperature
where coagulation is achieved), alkali (high alkali can induce gelling of egg
white).
When two unfolded protein molecules with their oppositely charged ends
approach each other, the molecules unite. Essentially, millions of protein
molecules join in a three-dimensional network, or simply, they coagulate,
causing the egg product to change from a liquid to a semisolid or solid and
desserts, such as cheesecake, where a lack of eggs or substitutions can
negatively impact final product height, appearance, firmness and mouthfeel.
There are more than 40 different proteins in a whole egg, some only located
in the white and others predominantly in the yolk. These proteins influence
the rate of denaturation and coagulation. Egg white protein coagulates
between 144° F and 149° F (62.2° C and 65° C); egg yolk protein coagulates
between 149° F and 158° F (65° C and 70° C); and whole egg protein
coagulates between 144° F and 158° F (62.2° C and 70° C). However, a
number of variables influence the rate of coagulation, as well as the ability
of the proteins to remain in the three-dimensional network.

Coating:

Egg products, such as egg whites or egg yolks, supply coating, gloss or
finishing to foods within the baking category. Consumers expect a certain
appearance on the outside of baked goods, such as color or finish. Food
color overall is an indicator of quality, including the color of finished baked

NAMRATHA KOLLU
38
products. The proper coating or finish not only aids with appearance but
can also help extend shelf life by sealing in moisture.
Slightly beaten liquid egg products can serve as a coating or glaze on baked
goods, with different variations of the egg mixture according to the desired
appearance and texture of the final product. A baker might select either egg
yolk, egg white or whole eggs for varying results.
The white is the primary source of proteins in an egg. When whites alone
are used as a coating the proteins coagulate and draw moisture from the
product, with eventually evaporates, resulting in a crisp surface. An egg
wash can also give the baked product a finished, slightly glossy look.
Protein browns when exposed to heat, so the addition of an egg wash helps
give baked goods a bronzed sheen, in addition to the gloss.
Slightly beaten yolk or eggs, brushed onto surface of unbaked good helps
prevent crust from drying out and lends a glossy look. Added at a certain
stage in the baking process, the egg wash can help prevent overbrowning.
However in order to seal in moisture, yolks must be used in the egg wash.
An egg wash application is common not just for bread, but also different
types of pastries or pies, to promote browning, create a glossy shine or
both. A variety of other ingredients added in different proportions to the
selected egg product (whole egg, egg white or egg yolk), will supply
different levels of browning, shine and even texture to the crust surface.

Flavor:

Eggs when used as an ingredient contribute to the flavor of finished
products and when whole eggs or yolks are used, the lipids within enhance
the eating experience. In general, fats such as those contained in whole eggs
and egg yolk influence rheological properties and sensory characteristics
such as flavor, mouthfeel and texture.

Stabilization:

Egg products can help control crystallization in confections, frozen desserts
and prepared foods. Two of the functions eggs supply, emulsification and
foaming, contribute to their ability to aid with crystallization control. Many
confections begin with a sugar solution in water. The proteins in egg whites
slow down the crystallization process of this sugar solution, or interfere
with the action of sucrose molecules to reduce their size and to create a
smoother texture and a more pleasant mouthfeel. Beaten egg whites allow

A TECHNICAL GUIDE OF EGGS IN FOOD

39
for foam formation and incorporate air into an otherwise dense
sugar/water solution, to enhance the melting quality of the product in the
mouth.
Egg yolk in ice cream or other frozen dairy-style desserts aids with density,
hardness and texture. Egg yolks help create smaller ice crystals, prevent the
ice cream from clumping and aid with whipping properties for desired
overrun. In frozen desserts the natural lecithin in eggs increases viscosity of
the base mix and interferes with the formation of large ice crystals. Smaller
ice crystals affect product density, hardness and texture.

Leavening:
Eggs can contribute to this process of leavening in two ways. First, when
fresh, refrigerated or frozen eggs are present in a formulation or recipe they
contribute liquid, which then converts to steam as the product is heated,
with this steam a primary factor in leavening.
Secondly, egg white when whipped aerates a product or helps create the air
cells that are eventually filled by steam. As the liquids within the baked
good turn to steam or form gases with heat, the steam pushes out the walls
of the air cells and expands them. In addition, as egg proteins coagulate
they form a network with gluten. The network formed between the
combination of proteins and starches sets the walls of the air cells to hold
the product shape once it cools. Eggs, according to multiple sources, have a
great ability to leaven or puff up foods when air is beaten into them, and
that they aid in leavening overall in baking applications.
Part of this is due to the fact that egg whites are capable of expanding or
creating a foam that is six to eight times their initial volume. When air is
incorporated into the protein molecules in egg whites, the proteins unwind
and stretch to form an elastic web that encases the air bubbles.
Adding an acid, such as cream of tartar, vinegar or lemon juice, can help to
strengthen and stabilize the egg white foam. Room temperature egg whites
create the best foam volume and stability.
Whole eggs and yolks can also trap and hold air that expands during
heating, leavening cake batters and other baked goods. Popovers, eclairs
and cream puffs for example, do not use chemical leaveners but rely on
steam, coagulation and starch gelatinization for structure to create their
characteristic shapes. It is the leavening action supplied by the liquid
ingredients such as eggs that creates the airy form due to a large cavity in

NAMRATHA KOLLU
40
the center. Baking helps the proteins coagulate and properly set the
structure

Fortification:
One large egg contains a wide variety of nutrients for a relatively low calorie
count, with just 70 calories containing 6 grams of high-quality protein. For
this reason, eggs and egg products are considered “nutrient-rich” according
to the definition of the USDA ARS. Nutrient dense foods and beverages
provide vitamins, minerals and other substances that may have positive
health effects with relatively few calories. In addition, the definition states
nutrients and other beneficial substances have not been ‘diluted’ by the
addition of energy from added solid fasts, added sugars or the solid fats
naturally present in the food.
Foods formulated with egg products contain all the nutrition originally
found in the egg product, including high-quality protein, trans-fatty acid
free mono- and poly-unsaturated fats, vitamins, minerals and other highly
bioavailable nutrients with recognized health and wellness benefits.

Humectant:
Egg proteins bind water making it less available for microorganisms to
grow and cause spoilage. Overall, eggs help reduce moisture loss from the
baked product to extend shelf life by helping form proper cell structure of
the baked product. Proper cell structure traps moisture and holds it,
whereas retrogradation or staling occurs when these cell structures collapse.
Particularly in gluten-free formulating, egg products help contribute
humectancy, to help optimize moisture, not just for better shelf life, but
also for better product density and rise.

Textural properties:
Eggs help set the structure the aid with baked good texture, in fact, the
uniformly open cell structure and fine crumb of many baked goods is due
to coagulation of egg proteins during baking.
Fats in the yolk produce a tender, soft crumb in baked goods such as
muffins and cakes and retard the onset and rate of firming that occurs with
age. Egg proteins within certain food matrices can help maintain product
moisture by binding the water in the structure, to prevent it from drying

A TECHNICAL GUIDE OF EGGS IN FOOD

41
out. In doing so, there are textural benefits, such as a desired level of
chewiness that help give products an improved mouthfeel.
Egg yolk contains lecithin and other phospholipids that act as natural
emulsifiers, with this emulsification property a benefit to aspects of finished
product texture. The emulsifying action of egg yolk helps produce smooth
batters, and subsequently, contributes to volume and texture. The egg as
emulsifier interacts with gluten to strengthen the protein network to create
a desirable texture. Emulsifiers improve gas bubble stability for a light,
tender and moist product, retarding staling.
Lecithin from the egg, in addition to increasing fermentation tolerance in
bread, and allowing it to exhibit better dough machinability in commercial
baking, also produces a better crumb color, tenderizes the crust and lends
the product a smooth texture, while maintaining grain uniformity and
lengthening product shelf life.

pH stability:
Whole eggs are relatively pH neutral, egg white is one of the few food
products that is naturally alkaline, with an initial pH value that can be as low
as 7.6 at time of lay, but with increasing alkalinity as the egg ages, and can
reach pH of 9.2. Factors that can influence the pH of the egg include the
age of the hen at the time of lay. The pH of a fresh egg yolk is about 6.0
and increases to 6.4 to 6.9 during storage. Storage at refrigerated
temperatures greatly slows the pH change and helps reduce the rate of the
thick egg white from thinning. In general, the egg pH is stable and does not
disrupt food product formulations.
In terms of foaming, a key functional benefit of egg white in particular,
proteins create more stable foams at a pH that is near 7.0 and are less
functional as that number rises to 9.0. In order to help stabilize egg white
foam, a common approach is to add cream of tartar, which lowers the pH
of the egg white and shortens the time necessary to produce a foam.

Whipping ability:
Eggs and egg whites can be whipped into a foam for aeration and to
improve product texture and appearance. Egg products whippability plays a
role in baking and frozen desserts such as ice cream, in addition to certain
confections. The various types of egg products display varying levels of

NAMRATHA KOLLU
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whippability, with differences between egg white, whole egg and egg yolk.
Dried eggs also perform in a different manner than liquid or frozen in
terms of whippability.
Pasteurization, a process applied to all further processed egg products, does
not impact whippability. Egg white for example is very stable in a dried
state and its whipping properties remain unaffected unless excessively high
temperatures are applied. However the whipping properties of egg products
containing yolk do witness a loss in efficacy when in dried form, so
refrigerated and frozen are recommended for certain applications.
In angel food cake, egg whites comprise the sole egg ingredient. Dried egg
white solids if chosen for application often are reconstituted prior to use.
Proper mixing procedures help maximize foam volume. In commercial
practice, egg white solids perform well with continuous batter mixing
systems. When whipped, the proteins within the egg white unfold or
denature to form a relatively stable foam structure useful in angel food cake,
as well as sponge cake, certain confections and other baking applications.
Whippability has a bit of a different meaning when it comes to ice cream.
Whippability refers to the whipping quality of the ice cream mixture itself.
The proper emulsifier, such as egg yolk, results in reduced air cell sizes and
a homogeneous distribution of air in the ice cream. The lecithin-protein
complex in egg yolk solids improves the whippability of ice cream, also
lending it a more dry appearance, smoother body and texture and a slower
meltdown. One reference indicates eggs have a pronounced effect in
improving the body and texture, have almost no effect on the freezing
point and increase the viscosity—all positive benefits in terms of ice cream
manufacture.
There are mix calculations that help formulate ice cream and frozen dairy
desserts, to determine the percentage required of the various ingredients.
Egg yolk solids are especially desirable in mixes in which butter or
buttermilk is used as a main source of fat. Egg yolks or whole eggs improve
the rate of whipping more if they are sweetened with 10 percent sugar or
corn syrup before they are frozen or dried.
Ice cream, according to the U.S. Code of Federal Regulations (CFR) can be
called custard or “French” if the egg yolk content is at least 1.4%.
References:
1. Stadelmen WJ and Cotterill OJ. (1995). Egg Science and Technology, Fourth
Edition, Haworth Press, Inc., New York, USA
2. Belitz H, Grosch W, Shieberle P. (2009). Food Chemistry, 4th revised and extended
Edition, Springer Berling Heidelberg

A TECHNICAL GUIDE OF EGGS IN FOOD

43
3. Pyler EJ and Gorton LA. (2010). Baking Science & Technology, Fourth Edition,
Volume 1, Sosland Publishing Co., Kansas City, Missouri, USA
4. Campbell J, Marshall R. (2016). Dairy Production and Processing: The Science of
Milk and Milk Products, Waveland Press, Inc., Long Grove, Illinois, USA
5. Marshall R and Arbuckle WS, (2000) Ice Cream, Fourth Edition, Aspen Publishers,
Inc., Gaithersburg, Maryland, USA
6. https://www.uoguelph.ca/foodscience/book-page/mix-calculations-ice-cream-
and-frozen-dairy-desserts
7.http://www.milkfacts.info/Milk%20Processing/Ice%20Cream%20Production.ht
m
8. Berry D. (2014). Naturally colorful. Baking Business, Sosland Publishing, Kansas
City, online
http://www.bakingbusiness.com/Features/Formulations/2014/7/Naturally-
colorful.aspx (Accessed May 23, 2017)
9. Munday E, Werblin L and Deno K. (2017). Yellow Batter Cake Application
Research: Comparing the Functionality of Eggs to Egg Replacers in Yellow Batter
Cake Formulations, CuliNex, LLC, Seattle, USA
10. Brown A. (2011). Understanding Food: Principles and Preparation, Wadsworth
Cengage Learning, Belmont, CA
11. Stadelmen WJ and Cotterill OJ. (1995). Egg Science and Technology, Fourth
Edition, Haworth Press, Inc., New York, USA
12. Pyler EJ and Gorton LA. (2010). Baking Science & Technology, Fourth Edition,
Volume 1, Sosland Publishing Co., Kansas City, Missouri, USA
13. Smith J, Hui Y. (2008). Food Processing: Principles and Applications John Wiley
& Sons
14. American Egg Board. “Extending the Shelf Life of Baked Goods.” YouTube,
narrated by Shelly McKee, Ph.D., Associate Professor, Department of Poultry Science,
Auburn University, Auburn, AL; Feb. 29, 2012

44

9. EGG POWDER

Spray dried whole egg powder with desired functional properties are used
by many segments of the food industry especially for bakery foods, fast
food (omelet), mayonnaise and salad dressing. For these products, optimum
spray drying conditions were determined for targeting to obtain the desired
value of functional properties, i.e.; emulsion stability, gel texture, foaming
stability and color change, separately, for the area of use or specific end-
product requirement. While maximum emulsion stability and gel texture
and acceptable foaming stability and color change were objected for bakery
foods, for the fast food (omelet) minimum gel texture, foaming stability and
color change and acceptable emulsion stability were the selected goals. For
mayonnaise and salad dressing type products maximum emulsion stability,
minimum gel texture and color change and acceptable foaming stability
were targeted. At the optimization stage, the air inlet temperature (165–
195 °C), air outlet temperature (60–80 °C) and atomization pressure (196–
392 kPa) were selected as independent factors. Numerical optimization was
performed for the process parameters of spray drying to obtain the
optimum quality whole egg powder for bakery foods, fast food and
mayonnaise and salad dressing.

Process flow chart for the manufacture of egg powder:

Fresh Egg collection

Cold storage 4-5?C

Candling & Inspection at 15?C

Cleaning with disinfectant/sanitizing (2% sodium hypochlorite) solution
Water temp at 43?C for 3 min

Breaking & collection

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45
Churning & filtration

Homogenization for 5 min

Pasteurization (62.5 for 5 min) (To destroy salmonella & other Micro
organisms)

Desugaring is done by adding 0.5% yeast to prevent Maillard reaction

Fermenting at 30?C for 11.5 hrs

Repasteurization (62.5 for 3-5 min)

Cooling &churning

Drying(3 ways)

Freezing Spray drying Foam
(Blast freezer)

Drying Inlet temp is 185?C Spreading
Out let temp is 85?C( So that mc is 2-4% )

Gas packaging Vacuum packaging

Storage Storage Drying in oven

600C for 24 hrs Mc reduced
to 2-4%

Gas packaging

Storage

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Changes in Egg powders on storage:

1. Discoloration of egg powder which may be caused due to
a. Reaction b/n phospholipids & aldehydes
b. Due to oxidation of USFA
c. Destruction of naturally occurring carotenoids
d. Interaction b/n amines & aldehydes and
e. Groups of lipids also contribute to discoloration called Lipid
browning

2. Loss of Nutritive value
3. Off flavor are produced
4. Loss of solubility
5. Non-enzymatic changes.

References:
1. Munday E, Werblin L and Deno K. (2017). Yellow Batter Cake Application
Research: Comparing the Functionality of Eggs to Egg Replacers in Yellow
Batter Cake Formulations, CuliNex, LLC, Seattle, USA

47

10. FORMULATIONS
Caesar Salad Dressing (liquid eggs)
Yield: 2 cups

Ingredients Percent (%)
Egg yolk, liquid 17.60
Lemon juice 87.98
Garlic, chopped 2.43
Mustard, Dijon 1.96
Anchovy fillets,
chopped
1.17
Salt, fine 0.49
Black pepper 0.10
Olive oil 58.65
Total 100.00
Method of Production:

1. Place all ingredients, except olive oil in a blender or food processor.
Mix on high speed, until homogenous.
2. On medium speed, slowly pour in oil in a very thin, steady stream
until the dressing is emulsified.
3. Cover and refrigerate until ready to serve.

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Tomato Confit

Ingredients Percent (%)
Tomato, diced,
frozen, reduced-
moisture
46.86
Garlic puree 14.06
Tomato Paste 14.06
Salt, fine 0.47
Brown Sugar 2.81
Rosemary cracked
16, RS9232
0.19
Olive Oil 15.93
Balsamic vinegar 5.62
Total 100.00
Method of Production:
1. Combine tomatoes and garlic puree and then spread on greased
parchment lined baking sheet.
2. Bake at 325° F for 10 minutes, until roasted and browned.
3. Mix the tomatoes with the remaining ingredients together until
combined.
Packaging/Serving:
1. Store frozen in a triple-sealed, double poly bag until ready to use.
2. Allow confit to thaw until room temperature for serving.

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49
Mexican Chocolate Biscotti

Ingredients Percent (%)
Flour, all-purpose 22.55
Cocoa powder 9.00
Cinnamon, ground 0.50
Cayenne pepper, ground
40,000 SHU
0.10
Chipotle power 0.10
Sugar, granulated 26.50
Baking powder 1.25
Salt, fine 0.25
Butter, unsalted 5.00
Egg, whole, liquid 25.00
Almonds, toasted, chopped 8.00
Vanilla extract 1.75
Egg white, liquid As needed for brushing
Total 100.00

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Method of Production:
1. Blend dry ingredients together with almonds.
2. In a stand mixer fitted with a paddle attachment, cream butter and
sugar together.
3. Add the eggs and vanilla. Mix on speed 4 until combined,
approximately 2 minutes.
4. Add the dry ingredients. Mix on speed 2 until just incorporated,
approximately 1 minute.
5. Divide dough into 450g portions. On parchment-lined baking
sheets, form dough into a 2-inch wide, 3/4-inch tall logs. Brush with
liquid egg white.
6. Bake at 350° F for 20 minutes. Rotate halfway through baking,
until dough is firm, but gives slightly when pressed.
7. Let cool on a wire rack for 5-10 minutes. Lower the oven
temperature to 325° F.
8. With a serrated knife, cut logs into 1/4-inch slices on the diagonal
and arrange cut-side down on parchment-lined baking sheets.
9. Bake at 325° F for 10 minutes, rotating halfway through baking and
flipping biscotti over. Biscotti should be crisp when done.
Packaging/Serving:
1. Let cool completely on a wire rack before packaging into
cardboard-lined poly bags with a light vacuum.
2. Store at room temperature.

ASIAN TRIANGLES (liquid eggs)
Yield: 16 pieces
Part 1 – Filling
Ingredients Percent (%)
Egg, whole, liquid 75.75
Salt, fine 1.18

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51
Chili oil, hot 0.40
Pepper sauce, hot, Thai 0.19
Lemongrass, seasoning, dried 0.39
Mushroom, Shitake, chopped 12.62
Onion, green, chopped 6.31
Basil, fresh, Thai, chopped 3.16
Total 100.00
Method of Production:
1. In a large bowl, combine the whole eggs, salt, hot chili oil, Thai hot
pepper sauce and lemon grass seasoning.
2. Pour the egg mixture into spray-coated skillet and cook and stir
until soft curds form.
3. Add the mushrooms, green onions and basil leaves into the egg
mixture.
4. Continue to cook for 1-2 minutes until eggs are firm and no visible
liquid egg remains.

5. Assembly
Ingredients Percent (%)
Part 1 – Filling 70.00
Wonton wrappers, 6-inch 30.00
Oil, vegetable, as needed
Total 100.00

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Method of Production:
1. Portion a heaping tablespoon (28g) of the filling mixture onto
center of each wrapper.
2. Moisten edges with water, fold in half and press to seal edges.
3. Fry in hot oil 2-3 minutes, until golden.
4. Drain; serve immediately.
Chocolate Chip Cookie Ice Cream Sandwiches (liquid eggs)
Yield: 24 servings

Part 1 – Chocolate Chip Cookies
Ingredients Percent (%)
Sugar, light
brown
11.75
Shortening 19.00
Sugar, granulated 11.75
Whole eggs,
liquid
7.25
Salt 0.41
Vanilla extract 0.70
Flour, pastry 31.70
Baking soda 0.19
Chocolate chips 17.25
Total 100.00
Method of Production:
1. Whisk brown sugar to break up any lumps.
2. In a standing mixer fitted with a paddle attachment, add the
shortening, sugars, egg and salt.
3. Cream together for 4 minutes on medium speed.

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53
4. Add the vanilla. Continue to mix for 2 minutes on medium speed.
5. Add the flour and baking soda and mix for 2 minutes on low.
6. Add the chocolate chips and mix on low until just incorporated.
7. Form 25g balls and place on an ungreased parchment paper lined
baking sheet about 2 inches apart.
8. Bake for approximately 14 minutes at 325° F, rotating after 7
minutes.
9. Cool completely and store in an airtight container until ready to
use.

Part 2 – Vanilla Frozen Custard
Ingredients Percent (%)
Egg yolk, liquid,
sugared
7.33
Sugar, granulated 14.29
Milk, whole 39.45
Vanilla extract 0.45
Heavy cream 38.48
Total 100.00

Method of Production:
1. Combine all ingredients except vanilla, and mix with an immersion
blender until homogenous.
2. Transfer into heat-safe poly bags and seal. Pasteurize at 161° F for
20 minutes in water bath. Alternatively, heat the mixture in a non-
reactive sauce pot over medium low heat, whisking constantly, until
160° F and slightly thickened.
3. Let mixture cool to room temperature then stir in the vanilla.
4. Cover and refrigerate for at least 3-4 hours before churning.
5. Once chilled, pour into ice cream machine and churn for 50
minutes.

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6. Transfer the thickened ice cream to a freezer-safe container and
freeze for at least 4 hours to harden. Store frozen until ready for
assembly.

Part 3 – Assembly
Ingredients Percent (%)
Part 1 – Chocolate Chip
Cookies
33.33
Part 2 – Vanilla Frozen
Custard
66.67
Total 100.00
Assembly
1. Place half the cookies on a sheet tray with the bottom sides up.
2. Scoop and spread the ice cream evenly on top of the cookie to
make a ½-inch even layer (about 40g or ¼ cup)
3. Place the other half of the cookies on top of the ice cream and
gently press to create a sandwich.
4. Package in sealed poly bags and keep frozen until ready to serve.

Sponge Cakes
Yield: 1 10-inch cake/10 to 12 slices
Ingredients
? 7.5 oz (200.4 g) frozen (thawed) liquid egg white
? 3/4 tsp. (3 g) Cream of Tartar
? 1/2 tsp (2.25 g) salt
? 1/2 cup (107 g) sugar
? 3.85 oz. (109.56 g) frozen (thawed) refrigerated liquid egg yolk
? 1/2 cup (107 g) sugar
? 3 tbsp. (45 ml) water

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55
? 1 tsp. (5 ml) vanilla
? 1 cup (110 g) all-purpose flour, sifted
?
Directions
1. Using mixer at high speed, mix egg whites, Cream of Tartar and
salt for 1 minute.
2. Gradually add sugar, 2 tablespoons at a time, beating until whites
are glossy and stand in soft peaks.
3. In another mixing bowl, beat together the egg yolk, sugar, water
and vanilla for 3 to 5 minutes.
4. Sprinkle flour over beaten whites. Add beaten yolk mixture. Gently
fold mixture until well combined.
5. Pour into ungreased 10-inch/25.5 cm tube pan. Gently cut through
batter with metal spatula or knife and spread evenly.
6. Bake in preheated 325° F oven until top springs back when lightly
touched with finger and cake begins to pull away from sides of pan,
about 35 to 45 minutes.
7. Invert cake in pan and cool completely, about 1 1/2 hours.
8. With narrow spatula or knife, loosen cake from pan and gently
shake onto serving plate.

Vegetable Omelet Pita Bread Sandwich (liquid eggs)
Yield: 6 sandwiches

Part 1 – Vegetable Mix
Ingredients Percent (%)
Green bell
pepper, diced
45.68
Tomato, diced 45.68

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seeded
Red onion,
minced
8.64
Total 100.00
Method of Production:
1. In a small bowl, combine the vegetables together.
2. Set aside until use in assembly.

Assembly
Ingredients Percent (%)
Pita bread 11.50
Olive oil 2.65
Part 1 –
Vegetable Mix
30.09
Spinach, fresh,
chopped
15.04
Egg, whole,
liquid
30.10
Mozzarella
cheese, shredded
5.31
Cheddar cheese,
sharp, shredded
5.31
Total 100.00
Assembly:
1. Prepare pita breads by cutting in half. Set aside.

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57
2. In a sauté pan over medium heat, heat olive oil. When oil is
hot, add Part 1 Vegetable Mix and sauté until translucent.
3. Add the spinach to the heated mixture and cook it down
until all the moisture is evaporated.
4. Add the whole eggs and stir constantly with a heat resistant
rubber spatula until soft curds form.
5. Add the cheese mix to the center of the prepared omelet
and heat until slightly melted.
6. Portion 500 grams into each pita pocket.
7. Cut each pita into 4 triangle servings.
8. Serve sandwiches with fresh fruit cup and a small tossed
salad.

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ABOUT THE AUTHOR

(Mrs.) Namratha Kollu, Head of the Department – Quality, Modern
Foods Enterprises Private Limited, Bangalore has B- Tech in (Food
Science) from Acharya N.G. Ranga Agricultural University and M-
Tech(Food Processing Technology) from Jawaharlal Nehru
Technological University, Kakinada
She has been heading the Department of Quality at Modern Foods
Enterprises Private Limited and current interest is in Nutritious Food
for all and Functional properties of animal proteins in food
processing.