Slide 8: Milk Overview Flashcards
Define milk
“A white or yellowish liquid consisting of small fat globules suspended in a water solution, secreted by the mammary gland for the nutrition of the newborn”
What are the components of milk?
Ø Water Ø Carbohydrates Ø Fat Ø Protein Ø Minerals & vitamins
What are the solids that make up milk?
Fat + Protein + carbohydrate + Min. & Vit. + enzymes
What are the solid-non-fat (SNF) components of milk?
Protein + carbohydrate + minerals & vitamins + enzymes
What are the components of skim milk?
Ø Skim milk (plasma): Milk - fat
Ø Whey (serum):
Skim milk - casein micelles
What are the proteins of milk?
casein, whey protein, MUN
What is the CHO component of milk?
lactose
A physical definition of milk:
“An emulsion of fat globules and a suspension of casein micelles all suspended in an aqueous milk serum phase”
How are fat globules found in milk?
Fat globules suspended in a relatively stable plasma phase
How are casein micelles found in milk?
Casein micelles in a colloidal suspension in milk serum phase
Strong negative correlation exists between lactose and:
Ø Milk fat
Ø Milk protein;
Protein (%) = 20 - 2.8 lactose (%)
Strong positive correlation exists between ______
milk protein & milk fat
Protein (%) = 1.05 + 0.57 fat (%)
How is milk osmolallity maintained?
Milk osmolality is maintained by lactose and diffusible ions. Therefore a negative relationship exists between lactose concentration and the sum of Na & K
A ______ relationship exists between lactose concentration and the sum of Na & K
negative
In milks where casein micelles are formed, a _______ correlation exists between casein concentration and Ca- P concentrations
positive
There is an ______ relationship between milk nutrient concentrations and suckling frequency
inverse
Species with precocious young secrete milk with _____ protein concentration than those with altricial young
lower
Compare the water content of milk in different mammals
donkey > cow > pig > rat > whale > seal
Variation in water content of milk among various cattle breeds
Holstein > Guernsey > Zebu = Jersey
What are the three groups of salts found in milk and their functions?
1- Ionic form: Na, K, Cl (diffusible). Maintain
osmotic equilibrium of milk with blood
2- Colloidal (nondiffusible) form: Ca, Mg, P, citrate (associated with casein micelles)
3- Diffusible salts of Ca, Mg, HPO–4 . Contribute to overall acid-base balance of milk.
Explain the milk fat’s general features?
Ø The most variable milk component in both concentration & composition
Ø Milks of some species contain little or no fat (e.g. black rhinoceros) while those of aquatic species (e.g. seals) contain > 50% fat
Ø Excellent source of energy (2.25 > protein & CHO)
Ø Adipose tissue (subcutaneous fat) protects the young in cold environment
What are the variations in milk fat among mammals?
Donkey < Human < Cow < Rat < Reideer > Whale < Seal
What are the variations in milk fat in cattle breeds?
Holstein < Brown Swiss < Ayrshire < Zebu < Guernsey < Jersey
What is the physical structure of milk fat?
Most of milk fat is in the form of fat globule