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Ansc 201 > Eggs > Flashcards

Eggs Flashcards

1
Q

What is the general purpose of eggs?

A

reproduction

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2
Q

What percent of the egg is comprised of the shell/shell membranes?

A

11%

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3
Q

What percent of the egg is composed of yolk?

A

31%

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4
Q

What percent of the egg is composed of albumen?

A

58%

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5
Q

What are some differences between bird eggs and mammalian eggs?

A

They differ in nutrient availability. Bird eggs are also larger than mammalian eggs.

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6
Q

What does altricial mean?

A

Altricial means that the offspring requires a large amount of parental care after hatching.

ex. baby birds

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7
Q

What does precocial mean?

A

The offspring require little parental care after hatching, and are able to function independently.

ex. chicks

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8
Q

What is the difference in egg content between altricial and precocial birds?

A

Altricial bird eggs tend to have less yolk and higher albumin contents than precocial birds.

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9
Q

What makes up the egg shell?

A
  1. cuticle layer
  2. spongy layer
  3. mammillary layer
  4. Shell membrane (inner and outer)
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10
Q

What is the egg cuticle?

A

The outermost layer of the shell

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11
Q

Which portion of the egg shell is the thickest?

A

the spongy (calcareous) layer

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12
Q

What are the functions of the egg shell?

A
  1. Strength
  2. Permitting gaseous exchange
  3. Preventing loss of egg contents and entrance of bacteria
  4. Serve as a nutrient source
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13
Q

Describe the strength of eggs shells.

A

The thickness of an egg shell correlates directly by the weight of the bird (i.e. bigger birds have thicker shells).

Calcium carbonate play a role in maintaining the structure, while the shell also has a cross-linked geometric design to further the shell’s integrity.

The egg shell must be thick enough to be sat on without breaking, and thin enough to be pecked through.

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14
Q

How do eggs perform gas exchange?

A

Via pores on the eggshell (around 10,000 pores per egg)

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15
Q

How is the eggshell a nutrient source for the developing embryo?

A

the shell serves as a small source of minerals

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16
Q

What is the shell membrane?

A

The shell membrane is made up of tough mats of protein fibers that help give the egg its structure.

There is an outer shell membrane that is closer to the shell, and an inner layer inside of the outer shell membrane.

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17
Q

What are air cells in eggs? How do they form? Where are they located? What purpose do they serve?

A

Air cells in eggs form when the membranes separate at the blunt end. The air cell forms as the egg cools, causing the liquids of the egg to retract and leave behind the air cell between the outer and inner shell membranes.

Location: blunt end of eggs between the outer and inner shell membrane

Purpose/function: supplies air to embryo when respiration is initiated

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18
Q

What are the functions of albumen?

A
  1. insulation
  2. shock absorption
  3. nutrient source
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19
Q

What percent of albumen is the outer thin layer?

A

23%

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20
Q

What percent of albumin is firm or dense?

A

57%

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21
Q

What percent of albumin is the inner thin layer?

A

17%

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22
Q

What percent of albumen is the chalaziferous layer (thick white; closest to the yolk)?

A

3%

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23
Q

What are chalazae?

A

The two twisted membranous strips that extend into the firm albumin to stabilize the yolk’s position in the egg by joining it to the ends of the shell.

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24
Q

What is the function of egg yolk?

A

to provide nutrients for the embryo

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25
Q

What is a blastodisk?

A

the unfertilized region of the egg yolk where embryos begin to develop; appears white, circular, and opaque

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26
Q

What is the blastoderm?

A

the fertilized region where the embryo develops; is oval shaped with a transparent center and opaque margins

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27
Q

Describe the components of the egg yolk.

A

The latebra is the tube-like structure where the embryo develops. It is surrounded by a layer of nutrients that deposit on the outside of this region. The vitelline membrane holds the yolk intact.

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28
Q

What is the latebra?

A

The tube-like structure where the embryo develops

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29
Q

What is the vitelline membrane?

A

It is the membrane that surrounds and keeps the egg yolk intact

it is thin, transparent, and very elastic to allow it to expand with the yolk contents

30
Q

What are blood spots in eggs?

A

Blood spots are a non-desirable quality found that can be found in eggs. They occur when vessels rupture in the yolk follicle at the time of ovulation, leaving a spot at the yolk’s surface

31
Q

What is a double yolk and how does it occur?

A

Double yolks are the most common defect in eggs. It occurs when two yolks meet in the oviduct and are included in the same shell.

32
Q

What does germicidal mean?

A

A process or substance that kills germs (bacteria, viruses, etc)

33
Q

How does the egg shell act as a germicidal agent in eggs?

A

Egg shells are the first line of defense in an egg. The calcium carbonate component of the shell is a drying agent that can dry out and kill bacteria.

34
Q

How do shell membranes act as a germicidal agent in eggs?

A

Shell membranes can act as filters since their pores are smaller that the pores in the actual shell. This makes it difficult for bacteria to pass through.

35
Q

What is avidin?

A

Avidin is a proteinaceous chemical defense in the albumin of eggs that interferes with bacterial growth.

36
Q

What are lysozymes?

A

Lysozymes are enzymes in the albumin that dissolve (lyse) bacteria. They are also commonly found in tears, membranes, etc.

37
Q

What percent of the egg content is water?

A

74%

38
Q

What percent of the egg content is dry matter?

A

26%

39
Q

What percent of the egg content is protein?

A

13%

40
Q

What percent of the egg content is fat?

A

11%

41
Q

What percent of egg content is carbohydrates?

A

1%

42
Q

What percent of egg content is minerals?

A

1%

43
Q

What causes variation in egg composition?

A
  1. type of bird/species
  2. strain of bird/breed
  3. day to day variation
  4. weather/climate
  5. nutrition
  6. disease status
44
Q

What types of minerals are common in eggs?

A

Ca, Cl, Fe, Mg, S, K, P, Na

Ca, Mg, and P are mostly found in the shell

remember, Fe and Na are deficient in milk

45
Q

What percent of the albumin is ovalbumin (egg protein)?

A

75%

46
Q

Describe the nutritional value of eggs.

A

Eggs contain nature’s highest quality protein. Their amino acid composition most closely meets the needs of humans.

47
Q

Where are lipids most commonly found in the egg?

A

mainly in the yolk

48
Q

What percent of egg lipids are triglycerides?

A

62%

49
Q

What percent of egg lipids are phospholipids?

A

5%

50
Q

What percent of egg lipids are sterols?

A

5%

51
Q

What percent of egg fats are saturated?

A

34%

52
Q

What percent of egg fats are unsaturated?

A

66%

53
Q

Why are egg phospholipids important?

A

They help prevent freezing and crystallization in the eggs. Eggs have a higher freezing point than milk, so that explains the higher phospholipid content.

54
Q

Describe egg carbs.

A

There are very few simple sugars and they are mostly found in the albumen

55
Q

Describe egg vitamins

A

Eggs are a good source of vitamins except for Vitamin C

56
Q

What constitutes a quality egg?

A
  1. sound shells
  2. clean shells
  3. freedom from blood or meat spots
  4. freedom from off flavors (that can be absorbed via the pores)
  5. uniform size, shape, and color
  6. uniform yolk color
  7. large amount of firm albumen
57
Q

What internal factors influence egg quality?

A
  1. genetic factors
  2. physiology
  3. nutrition
58
Q

What external factors influence egg quality?

A
  1. Temperature
  2. Humidity
  3. Contamination
59
Q

When is the egg at its best quality?

A

Immediately after it is layed by the hen.

60
Q

What is shrinkage in eggs?

A

Shrinkage is a process that causes the air cell to enlarge in eggs. It happens when the egg is stored in low humidity, causing a loss of water.

61
Q

What is liquefaction in eggs?

A

Liquefaction is when the yolk absorbs water and becomes runnier. It is directly related to temperature.

It occurs by the following process:

  1. Loss of carbon dioxide from albumen into the atmosphere
  2. albumen binds less water
  3. yolk enlarges from water from the albumen, becoming runnier
62
Q

How can liquefaction be prevented?

A

adding carbon dioxide to the atmosphere the eggs inhabit

63
Q

What are the ideal storage conditions for eggs?

A
  1. Clean eggs
  2. Clean and sanitary facilities
  3. Low temperature (35-45 degrees F)
  4. High humidity (>80%)
64
Q

What is egg grading and what are the grades?

A

Grading is classifying the individual eggs according to established standards.

Grades:

AA: the eggs bought in stores, small air cells
A: are used in egg products, but typically are not bought in stores; have large air cells
B: are used in egg products, but typically are not bought in stores; have large air cells

65
Q

What internal attributes are used to assign egg grades?

A
  1. condition of yolk
  2. condition and thickness of albumen
  3. size of air cell
  4. abnormalities
66
Q

What external factors are used to assign egg grades?

A
  1. shell soundness
  2. shell cleanliness
  3. shape
67
Q

What is candling?

A

Candling is a process where a light is shone through an egg to see the size of the air cell. This helps determine egg quality and grade.

68
Q

What is considered high and low quality yolk?

A

High quality if faintly or not visible

Low quality if very visible, and has free movement

69
Q

What is considered high and low quality for albumen?

A

Firm albumen is high quality

Liquified albumen is low quality

70
Q

Describe how blood spots relate to egg quality.

A

The absence of blood spots indicate a high quality egg, while the presence of blood spots indicate low quality eggs.

71
Q

What is plating?

A

Plating is a grading test where the egg is simply put on a plate.

The factors used are:

  1. how high the yolk stands (high heigh correlates to high quality)
  2. how far the albumen spreads (low spread correlates to high quality)

Ansc 201 (14 decks)

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