Eggs pt 2

Question 1

describe the chalazae

Answer 1

thick, strand-like material that extends from the egg membrane to the junction of the thin and thick albumin layers; keeps egg yolk in place within the egg

Question 2

describe the egg yolk

Answer 2

• yellow part located centrally in a healthy egg
• yellowness may vary based on the animal’s diet
• dense
• surrounded by vitelline membrane
• spherical when healthy
• contains a seminal disc

Question 3

what’s a seminal disc?

Answer 3

flat disk on the yolk where the sperm entered the egg for fertilization

Question 4

how much moisture is in the egg yolk?

Answer 4

48-50%; present as bound and free water

• bound to proteins by hydrogen bonds
• loosely dispersed through the yolk

Question 5

what percentage of the egg yolk is protein?

Answer 5

~16%

Question 6

what types of proteins are there in an egg yolk?

Answer 6

• lipoproteins
• lipid-free globular proteins
• phosphoproteins
• minor proteins

Question 7

what lipoproteins are there?

Answer 7

LDLP: density <0.98
HDLP: density > 1.0

Question 8

what are the LDLPs comprised of?

Answer 8

• triglycerides 65-70%
• phospholipids 28-30%
• cholesterol 5%

Question 9

what are the HDLPs comprised of?

Answer 9

phospholipids - 60%

TGA - 40%

Question 10

describe the lipid-free globular proteins

Answer 10

• lack any fat, only protein
• tend to be water soluble
• exhibit immune properties
• participate in heat-induced gelation

Question 11

describe phosphoproteins

Answer 11

• rich in phosphates

- phosphorylated because of high content of OH amino acids (esp serine)

Question 12

give the main example of a phosphoprotein in the egg yolk

Answer 12

phosvitin

Question 13

properties of phosvitin?

Answer 13

able to bind metal ions like Fe2+ and Mg2+

Question 14

why are eggs good sources of P, Fe, and Mg

Answer 14

phosvitin phosphorylated binding power

Question 15

what fats are present in an egg yolk?

Answer 15

• saturated fat
• unsaturated fat
• phospholipid

Question 16

what saturated fats are present in an egg yolk?

Answer 16

palmitic, stearic

Question 17

what unsaturated fats are present in egg yolk?

Answer 17

• monounsaturated (oleic) 40-45%

- polyunsaturated (linoleic) 20-25%

Question 18

what phospholipids are present in egg yolk?

Answer 18

phosphatidylcholine, phosphatidylethanolamine, ceramide; lecithins

mostly phosphatidylcholine

Question 19

benefit of phosvitins?

Answer 19

• prevent oxidative rancidity

- nutritional value

Question 20

what essential nutrients are part of eggs?

Answer 20

• high quality proteins (2 eggs will provide humans with about 20% of the proteins required in a day)
• essential fats/oils (PUFAs)
• all minerals (except calcium)
• excellent source of C, A, and D

Question 21

what happens when an egg deteriorates?

Answer 21

• ## thick albumen layer breaks down and becomes lighter; its capacity to hold the egg yolk in place is reduced because it’s no longer thick, so the yolk expands and becomes more fragile