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Flashcards in Exam One - Practice Test Questions Deck (13)
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Life cycle of the mammary gland

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


Stages of milk synthesis

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


Lactose synthase components

Galactosyl transferase and alpha lactalbumin


Short term and long term regulation of lactose production

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


Average milk composition

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


Creamery's ice cream base mix

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



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



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


Relevance of lactose in dairy foods

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


Batch pasteurization

145 F for 30 min


Continuous pasteurization

161 F for 15 sec


Functions of milk salts

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


Changes in milk due to mastitis

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