1. Milk composition. Milk products and human health.

What are the components of milk?

water
proteins
enzymes
fats
carbohydrates
minerals
vitamins

What is the water content in milk?

Almost 90%

What is the major protein group in milk that constitutes 80% of the protein?

Casein

What are the caseins?

α31, α32, β, κ

Is casein soluble in water?

No, it is insoluble in water

What is the biological function of casein?

To carry insoluble calcium and phosphate to young mammals and form a clot in the stomach for efficient nutrition

What percentage of milk protein is whey protein?

20%

What are the whey proteins?

α-lactalbumin, β-lactoglobulin, serum albumin, Ig

Is whey protein soluble in water?

Yes, it is soluble in water

Can whey protein denature by heat?

Yes, whey protein can denature by heat

What essential amino acids are found in whey protein?

Leucine and valine

What are some minor proteins found in milk?

Enzymes, metal-binding proteins, immunoglobulins, blood serum albumin, and bioactive milk proteins

What is an example of a metal binding protein?

lactoferrin (iron-binding)

What is the function of enzymes in milk?

To catalyse reactions

When is enzymatic activity higher in milk?

In colostrum compared to mid-lactation

What are exogenous enzymes in milk?

Heat-stable enzymes produced by psychotropic bacteria, including lipase and proteinases

What are indigenous enzymes in milk?

Lipoprotein lipase, plasmin, and alkaline phosphatases

What is the minimum milk solids not fat (MSNF)?

8.25%

What is the average fat content in milk?

Around 4%, but it varies
(buffalo, sheep, yak: 7-8%; reindeer: 16-20%)

What is the minimum milk fat?

3.25%

What are the main lipids in milk?

Triglycerides

Where do fats in milk originate from?

Microbial activity in rumen or synthesis in secretory cells.

What is the main carbohydrate in milk?

Glucose-based lactose

What major elements are present in milk?

Calcium, phosphorus, sulfur, chlorine, potassium, magnesium, sodium

What trace elements are found in milk?

Cobalt, copper, fluorine, iodine, iron, manganese, molybdenum, selenium, zinc

Which vitamins are present in milk?

Water-soluble (C, B-complex) and water-insoluble/fat-soluble (A, D, E, K)

What is included in non-protein nitrogen content in milk?

Ammonia, urea, creatine, creatinine

What percentage of total milk nitrogen is non-protein nitrogen?

5-6% (200-300 mg/L)

Why is milk essential for children?

It contains major components for growth and energy

What can babies utilize in milk that is beneficial for their health?

Immunoglobulins

Why is casein advantageous in older individuals but not in infants?

Due to its slow breakdown of milk, which is not advantageous in infants

What is the main issue with the vitamin content in milk for humans?

It has too low content of Vitamin D and iron

What is lactose intolerance and its symptoms?

A condition where reduced intake of milk lowers the amount of enzymes to break lactose down, causing watery feces and bloating due to bacterial degradation of lactose

Other than lactose intolerance, what is a common allergy in infants?

milk protein allergy (β-lactoglobulin)

What is the maximum amount of lactose in lactose-free milk?

0% (must be no lactose)

How does human milk compare to cow’s milk?

human lower in protein, higher lactose (7%)