Exam One - Practice Test Questions

Question 1

Life cycle of the mammary gland

Answer 1

Mammogenesis (pregnancy), lactogenesis (parturition), galactopoiesis (lactation), and involution (wean/dry)

Question 2

Stages of milk synthesis

Answer 2

Stage 1: differentiation of secretory epithelium occurs during the last third of pregnancy - organelles are formed and enzymes are expressed
Stage 2: completion of cellular differentiation and onset of copious milk synthesis and secretion - occurs during calving

Question 3

Lactose synthase components

Answer 3

Galactosyl transferase and alpha lactalbumin

Question 4

Short term and long term regulation of lactose production

Answer 4

Short term control by substrate: increased glucose demand can be met by an increase in mammary blood flow
Long term: expression of glucose transporters in plasma membrane and expression of alpha lactalbumin

Question 5

Average milk composition

Answer 5

Water 87
Fat 4
Protein 3.25 - casein 2.6, whey 0.6
Lactose 5
Ash 0.75
Total nonfat solids 9

Question 6

Creamery’s ice cream base mix

Answer 6

Butterfat 14
Milk solids - nonfat 10.5
Cane sugar 12.96
Dry corn syrup solids 3.7
Stabilizer/emulsifier 0.26
Total solids 41

Cocoa powder 3.5

Question 7

Stabilizer

Answer 7

Usually polysaccharides, added in small amounts, increases viscosity, produces a stable foam, melt resistance, smooth texture, slow moisture migration

Question 8

Emulsifier

Answer 8

Improve whipping quality of the mix, produces a dry and stiff ice cream, resists rapid meltdown, and promotes entrapment of air during extrusion

Question 9

Relevance of lactose in dairy foods

Answer 9

Lactose crystals: leads to caking – sandy ice cream - gritty texture
Lactose intolerance: some people cannot breakdown beta lactose - lacking the enzyme - beta galactosidase
Nonenzymatic browning: lactose is a reducing sugar - Maillard browning
Lactulose forming: strong thermal treatment leads to glucose isomerization - lactulose is sweeter than lactose - cannot be broken down by beta galactosidase

Question 10

Batch pasteurization

Answer 10

145 F for 30 min

Question 11

Continuous pasteurization

Answer 11

161 F for 15 sec

Question 12

Functions of milk salts

Answer 12

Age gelation of concentrated milk products
Feathering of coffee cream
Whipping of ice cream during freezing
Hardness and syneresis in cultured dairy products and cheeses

Question 13

Changes in milk due to mastitis

Answer 13

Decrease: lactose, casein, fat, K, milk yield
Increase: non-casein N, Cl, Na