Chapter 10 Milk

what contaminates milk

feces

udder infection

bacteria on skin

environment

unsanitary consitions

cross contamination from workers

____ is the only way to kill many of the ___ bacteria in milk that makes people sick

pasteurization ; pathogenic 

milk composition

87% water

13% fat and milk solids non fat

milk solid non fat (MSNF)

carbs proteins and micronutrients 

lactose

can be fermented into lactic acid which adds flavor to cheese and fermented milk product

two predominate milk protiens

casein: pirmary milk protein ; solid

whey: about 18% of milk protein ; liquid

milk fat characteristics 

important for flavor and mouthfeel 

consists of triglycerides sounded by protein and phospholipid membrane 

milk vitamins

fortified with vitamin A and D (fat soluble)

contains B2 (riboflavin) that can be destroyed by UV

contains tryptophan (aa) wich is a niacin (B3) precursor

to prevent B2 (riboflavin) degradation

cardboard or opaque packaging

milk mineral

calcium 

phosphorous 

pottasium 

magnesium 

sodium 

chloride 

sulfur 

color compounds

interfere with light transmission and contribute to opaque, ivory color

contributors to milk color

Fat

Dispersed proteins

Riboflavin

Amount of fat-soluble yellow pigments (carotenoids) in plants consumed by cow (contributes yellowish tinge)

pasturization

high temp short time to clear pathogens while keeping desirable sensory properties 

ultrapastuerization

heating raw milk 275-300F 2-4 seconds then aseptically packaged ; fresh 60-90 days

homogenization

mechanical process that breaks up fat globules in milk into smaller globules that do not clump together and are permanently dispersed

four types of cows milk (fat based)

1. Whole milk: 3.25% milk fat

2. Reduced-fat: 2% milk fat

3. Low-fat milk: 1% milk fat

4. Fat-free or non-fat milk: <0.5% milk fat

• all 4 must contain 8.25% MSN

other forms of milk (7)

1. non cow milks 

2. flavored milks stabilized by carrageenan (polysacch)

3. eggnog plant milks (no spacing in name e.g soymilk, almondmilk)

4. evaporated milk: 60% water removed 

5. sweetened condensed milk: 50% water removed and then sugar’s added 

6. nonfat dried milk (NFDM): all moisture is removed from milk (water restorers it) 

7. instant milk: made by exposing NFDM to steam and then re-drying it

fermented milk products

buttermilk: lactc acid lowers pH creating sour viscous product

sour cream: light cream is fermented

yoghurt

yoghurt making

mix Lactobacillus bulgaricus + Streptococcus thermophiles

add to pastuerized milk ;

keep at warm temp to ferment

creates lactic acid and folate

probiotic vs prebiotic yoghurt 

Probiotics: live microbial food ingredients [bacteria] that promote digestive health and wellness

Prebiotics: non-digestible food ingredients [usually fibers] that support the growth of probiotics

kefir

sour carbonated slightly alcoholic beverage

to make: add yeast/ bacterial fermentation to milk

cream: definition and types

definition: a collection of fat droplets that float to the

top of non-homogenized milk (18-36 of milk fat)

types:

coffee cream is 18-30% milk fat

whipping cream is 30-36%

coagulation and precipitation methods (3)

heat: denatures whey protein that coagulates with casien; forms a skin that can trap steam causong boiling over 

acid: casien protein denatures removing repulsive negative charge and making them nuetral to coagulate 

enzymes: caused coagulation via casein hydrolysis 

• chymosin or rennin or commercial rennet is the common enzyme

storage of milk products

refrigerate traditional fluid milks

dont drink from container (introduces more bacteria)

dry and canned ,ilk should be stored slightly below room temp