biochemical composition of milk

Question 1

factors that affect milk production and composition (5)

Answer 1

breed and species
feed/pasture
season/ temp
point of milking (fore/hind milk)
stage of lactation

Question 2

whta % of milk is milk solids

Answer 2

13%

Question 3

what are milk solids comprised of

Answer 3

fat
protein
enzymes
carbohydrates
minerals
vitamins

Question 4

what % of milk solids is fat

Answer 4

4%

Question 5

what % of milk solids consist of protein, carbs, minerals, vitamin, enzymes and organic acids

Answer 5

9%

Question 6

what % of milk is water

Answer 6

85-87%

Question 7

what properties does water give to milk

Answer 7

medium for milk solids
medium for dispersion of insoluble milk proteins
physical properties (conductivity)
affects shelf life

Question 8

what % of milk fats are triglycerides

Answer 8

98%

Question 9

what is the most variable component of milk

Answer 9

milk fats

Question 10

role of fat in milk

Answer 10

yellow colour from beta carotene
smooth mouth feel
calories
nutrients
flavour

Question 11

distribution of milk proteins

Answer 11

whey 18%
casein 80%
other proteins/ non-nitrogen protein 2%

Question 12

% composition of caseins

Answer 12

alpha s-1 - 32.4%
alpha s-2 - 8.5%
kappa - 9.4%
beta - 26.1
gamma - 2.4

Question 13

what is meant by casein proteins being conjugated

Answer 13

bound to Ca phosphate and aggregated into micelles

Question 14

why cant casein micelles be denatured by heat

Answer 14

disordered secondary structure

Question 15

% composition of cow milk whey

Answer 15

beta-lactoglobulin 9.8%
alpha-lactalbumin 3.6%
immunoglobulin 2.4%
bovine serum albumin 1.2%
protease peptone 2.4
miscellaneous 1.8

Question 16

why does casein have a disorganised secondary structure

Answer 16

high levels of proline cause bending

Question 17

role of alpha lactalbumin

Answer 17

controls lactose synthesis

Question 18

why does casein have a disorganized secondary structure

Answer 18

high levels of proline cause bending

Question 19

role of alpha lactalbumin

Answer 19

controls lactose synthesis

Question 20

role of beta lactoglobulin

Answer 20

no known biological function (not in human milk)

Question 21

role of bovine serum albumin

Answer 21

biochemical assay

Question 22

what does the cleavage of B-casein form

Answer 22

gamma-casein(hydrophobic) +proteose peptones (hydrophillic)

Question 23

indigenous enzymes in raw milk

Answer 23

lipases, lysoszymes, esterase, proteinases, catalases, lactoperoxidases, xanthin oxidase, phophatase

Question 24

role of lipases

Answer 24

rancidity in milk

Question 25

esterases role

Answer 25

cheese ripening

Question 26

proteinases (plasmin)

Answer 26

reduced storage stability of UHT milk
bitterness when pasteurised

Question 27

role of catalase

Answer 27

pro-oxidant-> index of mastitis

Question 28

role of lysozyme

Answer 28

bacterial agent

Question 29

lactoperoxidase

Answer 29

pro-oxidant: flavour development of cheese

Question 30

phophatase

Answer 30

index of pastuerisation

Question 31

what are lactose levels controlled by

Answer 31

alpha lactalbumin

Question 32

what enzyme is usedto make lactose free milk

Answer 32

beta-galactosidase

Question 33

what are human milk oligosaccharides

Answer 33

conjugated glycans

Question 34

health function of HMO

Answer 34

prebiotics
adhesive antimicrobials
intestinal epitheilial cell modulators
immune modulaters
brain development
modulators of key leukocytes

Question 35

water soluable vitamins in milk

Answer 35

thiamin, riboflavin, niacin, pantothenic acid, pyridoxine, cyanocobalamin
-B1, 2, 3, 5, 6, 12

Question 36

fat soluable vitamins in milk

Answer 36

ADEK

Question 37

minerals in milk (free ions0

Answer 37

NA
K
Cl

Question 38

mineral in milk (colliodial ions)

Answer 38

Ca
Mg
P
citrate
carbonates

Question 39

minerals in milk (diffusable salts)

Answer 39

salts of Ca, Mg, citrate carbonates, phosphate, sulfate