milk Flashcards
What are the major constituents of milk and their approximate mass percentages?
Water (~87%)
Fat (~3.5%)
Protein (~3.4%)
Lactose (~4.8%)
Minerals (~0.7%).
Name two key types of nutrients found in milk.
Macronutrients: Proteins, Fats, Carbohydrates (Lactose).
Micronutrients: Vitamins (A, D, E, K, B-complex, C) and Minerals (Calcium, Potassium).
What is the chemical structure of lactose?
β-D-Galactopyranosyl (1→4) β-D-Glucopyranose.
What is mutarotation in lactose?
The interconversion between α-lactose and β-lactose in solution.
Which form of lactose is more soluble: α or β?
β-lactose is more soluble than α-lactose.
Why is lactose classified as a reducing sugar?
Because its aldehyde/carbonyl group participates in reducing reactions like the Maillard Reaction.
What are the major lipids in milk?
Triacylglycerols (96-98%)
Phospholipids
Cholesterol
Free Fatty Acids.
What is the typical size range of milk fat globules in raw, unhomogenized milk?
2-10 µm in diameter.
How is milk fat dispersed in milk?
As an oil-in-water emulsion stabilized by amphiphilic lipids and protein coats.
What are the three sources of fatty acids in milk?
Diet.
Microbial activity in the rumen.
Mammary gland enzymes (synthase and desaturase).
What are the typical chain lengths of fatty acids in milk?
Short (C4-C10).
Medium (C12-C14).
Long (C16-C18).
What is the melting range of milk fat influenced by?
The composition of fatty acids.
What are the two main categories of milk proteins?
Casein (~80%).
Whey Proteins (~20%).
What are the major components of casein in cow’s milk?
αS1, αS2, β, γ, and κ-caseins.
What stabilizes casein micelles in milk?
lectrostatic repulsion (negative charge).
Steric repulsion from κ-casein on the micelle surface.
