2 Mammalian Nutrition Flashcards
(27 cards)
What are the major constituents of milk?
Water (~87%), fat (~3–4%), proteins (~3.3%), lactose (~4.8%), minerals (~0.7%), and vitamins (trace).
What is the definition of milk in terms of structure?
An aqueous solution of proteins, lactose, minerals, and vitamins with emulsified fat globules and colloidal casein micelles.
What are the major macronutrients in milk?
Proteins, fats, and carbohydrates (mainly lactose).
Name three fat-soluble vitamins in milk.
Vitamins A, D, and E.
What is the primary carbohydrate in milk?
Lactose.
What is the structure of lactose?
β-D-Galactopyranosyl-(1→4)-β-D-Glucopyranose.
What is mutarotation?
The interconversion between α- and β-anomers of lactose in solution.
Which form of lactose is more soluble?
β-lactose.
Why is lactose considered a reducing sugar?
It has a free aldehyde/carbonyl group that participates in reactions like the Maillard Reaction.
What role does lactose play in food chemistry?
It contributes to browning and flavor via the Maillard Reaction.
What is the major lipid in milk?
Triacylglycerol (TAG), making up 96–98% of milk fat
List two surface lipids found on the milk fat globule membrane.
Phospholipids and cholesterol.
What are the typical sizes of milk fat globules in raw milk?
2–10 µm in diameter.
Name two minor lipids in milk.
Sphingomyelin and gangliosides.
What makes milk an oil-in-water emulsion?
Fat globules dispersed in a continuous water phase.
What is the structure of a triacylglycerol?
Glycerol backbone with three fatty acid chains.
What is the melting range of milk fat?
Broad range due to varied chain lengths and saturation of fatty acids.
What are the sources of fatty acids in milk fat?
iet, rumen microbes, and mammary gland enzymes.
What process in the rumen modifies dietary C18 fatty acids?
Biohydrogenation.
What are the two main types of milk protein?
Casein (~80%) and whey (~20%).
Name the major whey proteins.
β-lactoglobulin (65%), α-lactalbumin (25%), BSA (8%), others (2%).
What is the isoelectric point of casein?
pH 4.6.
What are the structural features of κ-casein?
Contains trisaccharide side chains that aid steric stabilization.
What stabilizes casein micelles in milk?
Electrostatic and steric repulsion (κ-casein “hairy” layer).
