EGG CHARACTERISTICS4th Revision, 12 Nopember 2010
Nugraha E. Suyatma and Joko Hermanianto
Department of Food Science and Technology
Bogor Agricultural University
1
EGGAn egg is a round or oval cell laid by the female of any number of different species, consisting of an ovum surrounded by layers of membranes and an outer casing, which acts to nourish and protect a developing embryo.
2Which came first,
the chicken or the egg?
Edible egg:
• Chicken egg• Quail egg• Duck egg• Goose egg• Ostrich egg• Turtle egg• Fish egg: roe and caviar
3
Commercial Egg:
• These are hen eggs in shell, suitable for consumption in the state, or use by food industries, excluding broken eggs and boiled eggs (CEE Regulation No. 1907/90).
• Most laying hens are White Leghorns .
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Formation of the egg
5
• The egg is formed gradually over a period of about 25 hours.
• The female chick (Hen) has up to 4000 tiny ova (reproductive cells), from some of which full-sized yolks may develop when the hen matures.
• Each yolk (ovum) is enclosed in a thin-walled sac, or follicle, attached to the ovary
• The mature yolk is released when the sac ruptures, and is received by the funnel of the left oviduct
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Section of oviduct Approximate time egg spends in this section
Functions of section of oviduct
1 Funnel (infundibulum)
15 minutes Receives yolk from ovary. If live sperm present, fertilisation occurs here (commercially produced table eggs are not fertilised)
2 Magnum 3 hours Inner and outer shell membranes are added, as are some water and mineral salts
3 Isthmus 1 hour Albumen (white) is secreted and layered around the yolk
4 Shell gland (uterus)
21 hours Initially some water is added, making the outer white thinner. Then the shell material (mainly calcium carbonate) is added. Pigments may also be added to make the shell brown
5 Vagina/cloaca less than 1 minute
The egg passes through this section beforelaying. It has no other known function in theegg’s formation
Anatomy of an Egg
1. Eggshell2. Outer membrane3. Inner membrane4. Chalaza5. Exterior albumen6. Middle albumen7. Vitelline membrane8. Nucleus of pander9. Germinal disk10.Yellow yolk11.White yolk12.Internal albumen13.Chalaza14.Air cell15.Cuticula 8
SHELL (10 %)
• calcium carbonate (CaCO3) 94-97 %, 3-6 % Organic material and Pigment
• Shell strength is depend on the content of CaCO3, Mg, P, dan vit D
• Thickness: 0.2-0.4 mm• Pores: 700 pores/cm2 = 17,000 tiny
pores• Semipermeable membrane: air and
moisture can pass through has a thin outermost coating called the bloom or cuticle that helps keep out bacteria and dust.
• Mucin : covered shell and pores12
INNER AND OUTER MEMBRANES AND AIR CELL
INNER AND OUTER MEMBRANES Lye between the eggshell and egg white, these two transparent protein membranes provide efficient defense against bacterial invasion. If you give these layers a tug, you’ll find they’re surprisingly strong. They’re made partly of keratin, a protein that’s also in human hair.
AIR CELL • An air space forms when the contents of the egg
cool and contract after the egg is laid
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ALBUMEN (60 %)• The egg white is known as
the albumen, which comes from albus, the Latin word for “white.”
• contain approximately 40 different proteins:
• OVALBUMIN, CANALBUMIN, OVOTRANSFERIN, LYSOZYM, OVOMUCIN, AVIDIN, ETC
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Consist of 4 parts: inner thick, inner thin white, outer thick white dan outer thin white.
cloudy appearance due to CO2 content.
ALBUMEN
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Albumen
Proteins Lipids Carbohydrates Ash Water
9.7-10.6%, 0.03% 0.4-0.9% 0.5-0.6%
87.9-89.4%
Composition of Albumen (Powrie 1973)
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The egg white is approximately two-thirds of the total egg's weight out of its shell with nearly 90% of that weight coming from water.
Ovalbumin 54%Conalbumin 13%Ovomucoid 11%Lysozyme 3.5%Globulins (G2, G3) 8.0 %Ovomucin 1.5%
Other protein components include, flavoprotein (0.8%), ovoglycoprotein (0.5%), ovomacroglobulin (0.5%), ovoinhibitor (0.l%) and avidin (0.05%).
MAJOR PROTEINS IN ALBUMEN OF TOTAL PROTEINS (Powrie 1973)
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Egg white contains approximately 40 different proteins:
YOLK• Less water, more protein and fat than the
white egg• Contains most of the vitamins and
minerals of the egg, including Fe, vitamin A, vitamin D, phosphorus, calcium, thiamine, and riboflavin.
• Source of lecithin (emulsifier). • Yolk color ranges from just a hint of
yellow to a magnificent deep orange, according to the feed and breed of the hen.
• Umur: kuning telur mengabsorbsi air dari albumen: ukuran kuning telur membesar , strukturnya meregang, membran vitelin rusak, bentuk lebih flat.
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CHALAZAE AND VITELIN
CHALAZAE • Opaque ropes of egg white, the chalazae
hold the yolk in the center of the egg. Like little anchors, they attach the yolk’s casing to the membrane lining the eggshell. The more prominent they are, the fresher the egg.
Vitelline Membrane• The clear casing that encloses the yolk.
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Chemical composition of eggs
Animal Water (%)
Protein (%)
Lipid (%)
CHO(%)
Ash (%)
Chicken 73,7 12,9 11,5 0,9 1
Duck 70,4 13,3 14,5 0,7 1,1
Goose 70,4 13,9 13,3 1,5
Pigeon 72,8 13,8 12 0,8 0,9
Quail 73,7 13,1 11,1 1 1,1
Ostrich 72,6 13,1 11,8 1,7 0,8
Turtle 66,7 16,5 11,6 3,3 1,9
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Composition of egg
Component (%)Telur Utuh
Putih telur
Kuning telur
Kulittelur
Water 37 87,6 51,1 -Protein 12,9 10,9 16 4Lipid 11,5 - 30 -Carbohydrate 1,1 1,1 1,1 -
Free Carbohydrate 0,3 0,4 0,2 -
Ash 1 0,7 1,7 -Mineral 11,7 1 2 96
22
VITAMINS
Component Amount per 100 g egg
Vitamin A 190 µg
Vitamin D 1,8 µg
Vitamin E 1,1 mg
Vitamin C none
Thiamin (B1) 0,09 mg
Riboflavin (B2) 0,47 mg
Niacin 0.1 mg
Vitamin B6 0.12 mg
Folate 50 µg
Vitamin B12 2,5 µg Biotin 20 µg
Panthotenic acid
1.77 µg24
Minerals
• Iodine thyroid hormone
• Phosphorus for bone health.• Zinc for wound healing, growth and fighting
infection
• Selenium an important antioxidant
• Calcium for bone and growth structure and nervous function.
• also contain significant amounts of iron, the vital ingredient of red blood cells.
25
Lipids in Yolk
• Egg lipids are found mostly in yolk, only 0,05% is contained in albumen.
• Fatty acid content: monounsaturated (46.5%) > saturated (37.5%) >
polyunsaturated (16.5%)• Highest fatty acid content: monounsaturated: oleic acid (18:1) approximately
40% from lipid total.
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Fatty acid content in 100 g of fresh yolk
Fatty Acid Gram
Saturated 1.59
Miristat (14:0) 0.02
Palmitat (16:0) 1.14
Stearat (18:0) 0.40
Monounsaturated 1.95
Palmitoleat (16:1) 0.15
Oleat (18:1) 1.78
Eicosenoat (20:1) 0.01
Polyunsaturated 0.70
Linoleat (18:2) 0.59
Linolenat (18:3) 0.02
Arakidonat (20:4) 0.07
Dokosaheksanoat (22:6) 0.02
Cholesterol 0.21
TOTAL 4.43 27
Chemical composition change:
Liquid /Dry Egg
(per100g)
Liquid*/Frozen Dried
Whole Eggs Yolk White Whole Eggs Yolk Stabilized
White
SOLIDS-g 24.80 43.20 11.0 96.3 97.3 93.5
pH-g 7.8 6.7 8.8 8.7 6.5 6.8
PROTEIN-g 12.0 15.3 9.3 48.4 33.7 84.6
LIPIDS-g 9.71 23.0 0.076 39.2 52.9 0.407
FREE GLUCOSE-g
<0.10 0.2 0.3 0.3 <0.1 0
ASH-g 0.80 1.4 0.4 3.4 3.3 3.6
MOISTURE-g 75.20 56.80 89.0 3.7 2.7 6.5
28
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Important Nutritional Value of Egg
1. One medium egg contains between 4-5 grams of fat
2. High cholesterol• ~200 mg/egg
3. High in Complete Protein (EPR=93.7%); > milk (84.5%), fish (76%), beef meat (74.3%), soy bean (72.8%), corn (60%)
4. Little to no CHO
5. High in vitamins & minerals• Vitamins ADEK, some B vitamins, selenium, iodine,
zinc, iron, copper
Energy value of eggs
Protein
• 78 kilocalories (324 kilojoules) • only around 3% of the average energy
requirement of an adult man and 4% for an adult woman.
Protein• 12.5% of the weight of the egg in both the yolk
and the albumen.• Egg protein is of high biological value as it
contains all the essential amino acids needed by the human body.
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Functional Properties of Egg
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1. Flavor, color, nutrition2. Foaming agent3. Emulsifying agent4. Aids in thickening/structure5. Binding/coating agent6. Leavening agent
FOAMING PROPERTIES
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1. Air trapped in a liquid
2. In egg foam, air trapped by protein.
3. Denatured and then coagulates
4. Heat expands protein/air• Important to souffles,
meringues, omelet, and sponge cake.
EMULSIFIER CAPACITY
Egg yolk is a source of lecithin, an emulsifier and surfactant.
Lechitin is a substance that helps an emulsion form, or helps keep an emulsion from separating
Aplication :• Mayonnaise• butter sauces• salad dressing• Stabilizer of bakery products• Whipped egg
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Properties ApplicationThickening Eggs thicken foods like custards puddings, sauces,
and creamy fillings
Leavening Souffles, sponge & butter cakes, quick breads, andpuffy omelets are leavened by eggs
Coating Meat dishes, breads, and cookies are some foodswith egg components as the base ingredients forcoatings
Binding Eggs bind other ingredients for making meat loaves,casseroles, and croquettes
Emulsifying Eggs prevent mixture separation in mayonnaise,salad dressing, and cream puff filling
Clarifying Tiny particles are coagulated in soups and coffee tocreate a clear solution
RetardingCrystallization
Crystallization of sugar is slowed in cake icings andcandies
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ANTIMICROBIAL AND ALERGEN ON ALBUMIN
• LYSOZYME• Immunoglobulin E (IgE)
memicu histamin• OVOMUCIN (hambat enzim
tripsin)• AVIDIN: mengkompleks biotin
(Avidin+Biotin komplek): Biotin tak dpt dicerna
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Daily NeededNutritional analysis of egg without its shell
For a medium egg (Av 58g)
Constituent of Egg Amount per egg
% of Reference Nutrient Intake (RNI)
Amount per 100g egg
For adult female 19-50
years
For adult male19-50
years
Weight1 51.6 - - 100.0
Water g 38.8 - - 75.1
Energy kjoules/ kcalories
324/78 4 3 627/151
Protein g 6.5 14 12 12.5
Carbohydrate g trace - - trace
Fat g 5.8 ** ** 11.2
Inc saturated f.a. g 1.7 ** ** 3.2
Monounsaturated f.a
g 2.3 ** ** 4.4
Polyunsaturated fa.t
g 0.9 ** ** 1.7
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Benefit of Egg Components• Sialic acid could prevent infection • Immunoglobulin in yolk can play a role as
antibody.• PHOSVITIN has a function as food antioxidant.• Choline: aids brain function and enhances
thinking capacity and memory. It is an important part of a neurotransmitter that helps preserve the integrity of the electrical transmission across the gaps between nerves.
• Lutein and zeaxanthin: contribute to improving eye health and protecting eyes from ultraviolet rays
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Allergen in Egg• There are 4 proteins in egg white may provoque
an allergy:- ovomucoid (11%)
- ovalbumin (54%)- ovotransferrin (12%)- lysozyme (3.5%)
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Egg Allergy Symptoms
Egg allergy is like most food allergy reactions: It usually happens within minutes to hours after eating eggs.
• the skin - in the form of red, bumpy rashes (hives), eczema, or redness and swelling around the mouth
• the gastrointestinal tract - in the form of belly cramps, diarrhea, nausea, or vomiting
• the respiratory tract - symptoms can range from a runny nose, itchy, watery eyes, and sneezing to the triggering of asthma with coughing and wheezing
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EGG QUALITY
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Egg Quality
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Exterior egg quality – shell quality based on shell cleanliness, shell soundness, shell texture, shell shape.
Interior egg quality – based on relative viscosity of the albumen, freedom from foreign matter in the albumen, shape and firmness of the yolk, and freedom from yolk defects.
Shape Index of Egg
Ideal shape (USDA)
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Shape index of egg = A/B x 100A = the biggest diameter (cm)B = The longest of length (cm)
Candling
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• Candling is the process of holding a strong light above or below the egg to observe:
• cracks, checks and weak shells• blood or meat spots.• Egg air cell• size of yolk and its movement• double yolk, yolkless, etc.• Become familiar with interior
quality.
Egg Grading
Grade
size
49
Sizing
50
Peewee: less than 42 g
Small: at least 42 g
Medium: at least 49 g
Large: at least 56 g
Extra Large: at least 64 g
Jumbo: at least 70 g
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• Sizing is not related to grading in any way.• Eggs are sold in cartons by various sizes determined by a
minimum weight for a dozen eggs in their shell.
Grading
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Grade AA Grade A Grade B Break Out Appearance
Covers a small area. Covers a moderate area.
Covers a wide area.
Albumen Appearance
White is thick and stands high; chalaza prominent.
White is reasonably thick, stands fairly high; chalaza prominent.
Small amount of thick white; chalaza small or absent. Appears weak and watery.
Yolk Appearance
Yolk is firm, round and high.
Yolk is firm and stands fairly high.
Yolk is somewhat flattened and enlarged.
Shell Appearance
Approximates usual shape; generally clean,* unbroken; ridges/rough spots that do not affect the shell strength are permitted.
Abnormal shape; some slight stained areas permitted; unbroken; pronounced ridges/thin spots permitted.
Usage Ideal for any use, but are especially desirable for poaching, frying and cooking in shell.
Ideal for any use, but are especially desirable for poaching, frying and cooking in shell.
Good for scrambling, baking, and as an ingredient in other foods.
Grading
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GRADE A: sold at retail store
yolk is round, well centred
white is thick
small air cell (less than 5 mm deep)
shell is clean, uncracked and of normal shape
GRADE B : only a small percentage sold at retail stores; most go to further processing market
yolk is slightly enlarged or flattened
white is moderately thin
shell uncracked
GRADE C: not sold at retail stores; all go to further processing market
yolk is enlarged or flattened
white is thin and watery
shell may be cracked and stained
Grade
Grade Grade AA egg covers small area and stands high; white is thick and firm; yolk is high and round.
Grade A egg covers moderate area; white is reasonably firm and stands fairly high; yolk is
high.
There are three consumer grades for eggs: U.S. Grade AA, A, and B. The grade is determined by the interior
quality of the egg and the appearance and condition of the egg shell. Eggs of any quality grade may differ in
weight (size). 55
Egg White Index
• Egg white index (EWI)
Height of thick albumen EWI =
diameter of thick albumen (longest+shortest)/2
Newlaid Egg has the value: 0.050 – 0.174
Good quality if the value: 0,090 – 0,12057
Egg Yellow Index (EYI)
height of yolk EYI =
diameter of yolk
Good quality if EYI : 0,33 – 0,50
Average value: 0.42.
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Haugh Unit• Haugh unit (HU)
HU= 100 log [h-(√G(3w0.37-100)+1,9]
100HU= Haugh unit
h = heigh of thick albumen (mm)
G= 32,2
w= whole egg weight (g)
59
Fresh egg: HU=100Good quality: HU = 75; acceptable until 50Bad quality (Spoiled egg): HU < 50
Egg Handling• Egg quality is affected by temperature and
relative humidity of storage room.• Need to preservation
Egg preservation principles:• Avoid spoilage microorganisme enter• Minimize the loss of water and gas from
egg.Aplication:• freezing, chilling, dry packaging, coating
with essential oil, dipping in various liquid.61
Commercial Egg Production and Processing
Courtesy of Ryan A. Meunier & Dr. Mickey A. Latour; Purdue University 66
Egg Production
The objective of this presentation is to provide a general overview of commercial egg production and processing.
The slides are ordered in a sequential series as they occur in the production cycle.
This particular egg production facility is considered an “in-line” operation. This means the eggs are produced and packaged for shipping to retail markets on the farm. There are also many “off-line” operations that produce eggs in one location and transport them to another location for processing.
67Courtesy of Ryan A. Meunier & Dr. Mickey A. Latour; Purdue University
On the horizon is an in-line commercial egg production facility. This facility is vertically integrated or self-contained, i.e., the company owns the feed mill, hens, buildings, egg processing facility, and transportation vehicles.
68Courtesy of Ryan A. Meunier & Dr. Mickey A. Latour; Purdue University
A
A
A
This facility represents one level of vertical integration, the feed mill. Based on demand, raw grains (from bins “A”) are mixed into designated poultry rations and augured (“B”) to the layer houses.
B
69Courtesy of Ryan A. Meunier & Dr. Mickey A. Latour; Purdue University
The auger system delivers grain into high-rise layer houses (“C”). These houses are approximately 500 feet long and may contain as many as 150,000 laying hens.
C
C
70Courtesy of Ryan A. Meunier & Dr. Mickey A. Latour; Purdue University
This is a view of the inside of a layer facility. Hens are housed on slanted wire-mesh floors. Nipple waterers (“A”) serve as the hen’s source of water and the feed is transported through the house via an auger system in feeders (“B”).
B
B
B
A
B
71Courtesy of Ryan A. Meunier & Dr. Mickey A. Latour; Purdue University
This is another view of the egg transporting mechanisms within a layer house. The use of advanced mechanical engineering has greatly reduced the occurrence of human egg handling to the point that eggs are rarely touched by human hands.
72Courtesy of Ryan A. Meunier & Dr. Mickey A. Latour; Purdue University
As the eggs reach the end of each level, automatic collectors place the eggs into plastic egg handlers (“D”). Plastic egg handlers carry the eggs directly to the egg processing facility via a large overhead belt.
DD D
73Courtesy of Ryan A. Meunier & Dr. Mickey A. Latour; Purdue University
These eggs are traveling to the egg processing/breaker facility.
74Courtesy of Ryan A. Meunier & Dr. Mickey A. Latour; Purdue University
Eggs are mechanically washed with a mild detergent and sanitized (“E”). Eggs are washed in 120oF water.
E
E
75Courtesy of Ryan A. Meunier & Dr. Mickey A. Latour; Purdue University
Here the eggs are entering the first stage in the egg grading process. The eggs are evaluated by an automated computerized detection system. Eggs are graded into categories of AA, A, B, and Loss Quality Standards.
76Courtesy of Ryan A. Meunier & Dr. Mickey A. Latour; Purdue University
Brushes transport eggs away from the egg graders to the packaging area of the plant. It is at this point that eggs will either be placed into cartons or be sent to the breakers.
77Courtesy of Ryan A. Meunier & Dr. Mickey A. Latour; Purdue University
This is a view of the entire “carton line.” Each stack of cartons (blue, white, yellow, pink) represents a different egg size.
78Courtesy of Ryan A. Meunier & Dr. Mickey A. Latour; Purdue University
Eggs are mechanically placed into cartons for shipping to the grocery market.
79Courtesy of Ryan A. Meunier & Dr. Mickey A. Latour; Purdue University
Eggs awaiting processing within the plant are placed on plastic skids. These skids are washed and sanitized on a daily basis.
80Courtesy of Ryan A. Meunier & Dr. Mickey A. Latour; Purdue University
On the left, eggs are stacked in cardboard flats for shipment to the retail market. Eggs on the right are stacked in plastic flats and are awaiting transfer to the egg further processing (breaker) room. Again, plastic is used inside the plant for sanitation and recycling purposes.
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This is an egg breaker machine. This machine cracks the egg shells and separates the yolk (yellow) from the albumen (white). The separation process works exactly like a household egg strainer. This machine will process 18,000 eggs per hour.
83Courtesy of Ryan A. Meunier & Dr. Mickey A. Latour; Purdue University
This is also egg breaker machine. However, this machine will process 500,000 eggs per hour.
84Courtesy of Ryan A. Meunier & Dr. Mickey A. Latour; Purdue University
These are bulk bins full of pasteurized egg yolks awaiting shipment. Egg pasteurization occurs at 145oF for seven minutes for 3,000 pounds of egg.
87
Processed egg products leave the facility via 1/2 gallon “milk” cartons, bagged product, and bulk semi-trailers. Processed egg products also include hard-boiled eggs.
88Courtesy of Ryan A. Meunier & Dr. Mickey A. Latour; Purdue University
Eggshells are processed in the plant. The shells have been dried and ground for use in animal feeds and other products.
89Courtesy of Ryan A. Meunier & Dr. Mickey A. Latour; Purdue University