Lecture 2- Milk Flashcards
Biological definition of milk
Liquid normally secreted by female mammals for nourishment of their young
Chemical definition of milk
A colloidal suspension of organic and inorganic food substances consisting of water, fats, carbohydrates, proteins, mineral salts, some bacteria, enzymes, and vitamins.
Legal definition of milk
= lawyer wording and lots of wiggle room
% water in milk
87%
% fat in milk
3.8% (w/ genetics up to 4.2%)
% caseins in milk
2.8%
% albumins/lactalbumin/globulins in milk
.7
% lactose/sugar in milk
5.0 = leading solid component
% ash (minerals) in milk
.7%
% total solids in milk
13%
% total solids non-fat (SNF) in milk
9.2%
% Proteins in milk
3.5%
% fat in whole milk
3.2%
Fat exists in milk as a …
Temporary emulsion
Fat globules membranes contain 3 things and have a ____ charge
Phospholipids, proteins, enzymes, negative
What percent of milk liquids in triglycerides
98-99%
What percent of milk lipids in phospholipids
.2-1%, in membrane and only partially soluble in water= emulsifying agent
What percent of milk lipids is sterols? Waxes and vitamins are trace.
.25%
Triglycerides have a
3-carbon backbone
Fatty acid
R-C-OH, with =O on C
Saturated=
All single bonds between carbons
Unsaturated=
At least 1 double bond in carbon chain
What percent of fatty acids in milk are saturated
66% 2/3
What percent of fatty acids in milk are unsaturated
34% 1/3
What three fatty acids give male goats their smell?
Caproic 4, Caprylic 8, Capric 10
10 Major fatty acids in milk lipids and number of carbon atoms
Butyric 4 (smells), Caproic 6, Caprylic 8, Capric 10, Lauric 12, Myristic 14, Palmitic 16, Stearic 18, Oleic 18=, Linoleic 18==
Why does cream rise to the top? (Pyramid of 4)
Specific gravity (fat .9, water 1, whole milk 1.03, other milk solids 1.5)
Lactose (building blocks, creation, compare to sucrose)
Glucose + galactose, only made in mammary glands so milk is only natural source; lower solubility and less sweet than sucrose
Lactose exists in milk in …
True molecular solution
Proteins exist in milk in…
Colloidal dispersion
Surplus lysine in milk helps to…
Offset lysine deficiencies in cereal proteins such as corn (genetically engineered some corn to have more lysine)
Most abundant milk protein
Caseins; only from mammary tissues, contained as micelles, beta caseins (A1/A2) for health
What are the 2 whey (serum) proteins and their importance
Lactalbumin (more), lactoglobulin as immunoglobulins
Do eggs or milk have better nutritional value based on protein quality?
Eggs
Two methods of curd formation
1) enzyme (hard elastic curd) 2)acid (soft curd)
Specifics of enzyme curd formation
Rennin or pepsin hydrolysis kappa casein to paracasein; which binds with Ca2+ and clots to form calcium paracaseinate; left over= sweet whey
What are the 5 components of calcium paracaseinate?
Casein, calcium, vitamins, water, enzyme
What are the 6 components of sweet whey?
Water, lactose, minerals, albumin, globulins, vitamins.
Specifics of acid curd formation
Isoelectric point= negative. + pos. Charges combine; pH of 4.67; caseins precipitate
Ash exists in milk in …
True solution
What 8 minerals are present in milk?
K, Ca, S, P, Mg, Cl, Zn, Se
What 4 minerals is milk a bad source for?
Fe, Cu, Mn, Na
What is the most abundant mineral in milk?
K (but also in other foods, so Ca content is marketed)
Define vitamins
Organic catalysts
What makes Jersey cow milk special?
High carotenes split in 2 Vitamin A and give yellow color to milk
What to vitamins are fortified during milk processing.
A (vision) and D (absorb Ca and prevent osteoporosis)
What 4 vitamins are fat soluble in milk?
A, D, E, K (varies by diet)
What two vitamins are water soluble in milk?
B complex, C (stable composition)
What three factors influence milk composition?
Species, Breed, Stage of lactation
What 4 minor components of milk?
Vitamins, Enzymes (lipase), Somatic cells (from mammary lining), Leucocytes (white blood cells, must be low levels)
Colostrum has high % of what solid?
Albumin and globulin (12%, normal is 1%)
Is there more fat in first or late streams?
Late streams
What 5 factors influence animal performance?
Nutrition, diseases, genetics, seasons, age
3 types of flavor defects in organoleptic properties
Absorbed (transmitted), bacterial, chemical
Specifics of Absorbed (transmitted) flavor defects? (Flavor, causes, prevention)
Not dangerous, feeds/corny/barny flavor, weeds- onion or garlic, transfer from air to milk, don’t feed before milking, keep milk away from aromatic items in fridge
Specifics of microbiral flavor defects (flavors, causes, prevention)
Very dangerous (especially in raw milk), acid/putrid/malty flavor, caused by improper cooling or sanitation, at home don’t leave milk out too long
2 types of chemical flavor defects
Oxidized/ oxidative rancidity and lipolyzed/ hydrolytic rancidity
Specifics of oxidized flavor defects (flavor, causes, prevention)
Not harmful, papery/cardboardy, oxidation of fatty acids catalyzed by copper/ iron or ultraviolet light, (breaks double bond and adds oxygen), use stainless steel equipment and proper packaging
Specifics of hydolytic rancidity flavor defects (flavor, causes, prevention)
Bitter/soapy flavor, enzymatic hydrolysis of triglycerides from lipase freeing fatty acids, tons of lipase in small intestine and critical to digest fats, avoid excess agitation/stirring, pasteurization
Define pasteurization
Partial sterilization; heat up to denature proteins and kill microbes, does not effect absorbed or oxidative rancidity; juices also; purpose is to protect public health
Define standardization
Stabilize composition of commercially produced milk by adding additional skim milk to achieve desired fat content
3 types of pasteurization
LTLT (145F, 30 min.), HTST (161F, 15 sec.), UHT (280F, 2 secs.)
2 things ultra-pasteurization does to the milk?
Changes protein structures and prepares it for bad refrigeration
Homogenization
Process that involves using screens to reduce the size of fat globules.
What does the centrifuge separate?
Milk + cream
What does ultrafiltration (UF) separate?
Milk components based on molecular size
What is the purpose of reverse osmosis on milk?
To make it cheaper to transport
Grade is based on …
Conditions of farm (most US farms are grade A)
What is the % fat in skim milk?
Less than .5%
What is the % fat in reduced fat milk?
2%
What is the %fat in low fat milk?
1%
What percent of SNFs is milk fortified to?
10.25% (normal = 9.2%)
% fat in cream
10-36%
% fat in ice cream
More than 10%
% fat in butter
At least 80%
% fat in eggnog
At least 6%
Greek yogurt requires ___ times more milk to produce than conventional yogurt.
4
Cultured dairy products=
Microorganisms (from starter cultures) are used in the production of
What amt. of whole milk is used to produce 1lb of butter?
21.2lbs
What amt. of whole milk is used to produce 1lb of cottage cheese?
6.2 lbs
What amt. of whole milk is used to produce 1lb of ice cream?
12lbs
What amt. of whole milk is used to produce 1 lb of cheese?
10lbs
Imitation products are
Nutritionally inferior (made with water, corn syrup, and vegetable fats instead)
Substitute products
Have similar nutritional value to og product
Milk allergies effect
2-3% of kids younger than 3 (most grow out of it)
