Module 7-what is milk?

Question 1

what is milk

Answer 1

Commercial dairy milk is the post-colostrum mammary secretion of cows (goat milk is considered to be in a separate category, as is the milk from any other species)

Question 2

what nutrient groups does milk include? how digestible is it?

Answer 2

Milk is a complete food containing all of the five major nutrient groups (carbohydrates, proteins, fatty acids, minerals, and vitamins) in sufficient amounts and in digestible forms.

Question 3

what is milk made up of

Answer 3

Milk is made up of water, lactose, fat, protein and ash (minerals)

Question 4

what is the most variable component of milk

Answer 4

The most variable component is fat

Question 5

is the major carbohydrate of milk

Answer 5

lactose

Question 6

where is lactose mostly found

Answer 6

it is found almost exclusively in milk

Question 7

what is lactose

Answer 7

Lactose is a disaccharide sugar derived from galactose and glucose; its systematic name is β-D-galactopyranosyl-(1->4)-D-glucose

Question 8

what is lactose designed for

Answer 8

Lactose is an energy source for young animals

Question 9

who cannot break down lactose

Answer 9

individuals who are lactose intolerant

Question 10

what is lactase

Answer 10

The enzyme that breaks down lactose

Question 11

where is lactase produced

Answer 11

lactase is normally produced by the small intestine

Question 12

what does lactase break lactose into? where is it absorbed?

Answer 12

it breaks lactose down into glucose and galactose which are absorbed from the small intestine

Question 13

what happens in the digestion of lactose in a lactase intolerant person

Answer 13

Lactose intolerant individuals produce insufficient lactase and intact lactose is transported to the colon where its interaction with the normal colonic microorganisms creates the symptoms of lactose intolerance

Question 14

how does lactose impact the properties of milk

Answer 14

The chemical properties of lactose impact the chemical and physical properties of milk and milk products. Specifically, lactose gives milk its sweetness, smooth texture and colour

Question 15

how much lactose is in cows milk

Answer 15

Lactose constitutes four to five percent of cow’s milk

Question 16

Lactose constitutes four to five percent of cow’s milk how does this compare to other mammals

Answer 16

it is absent or present in extremely low quantities (i.e. less than 0.1 percent) from the milk of seals, sea lions and monotremes such as the platypus while lactose makes up seven percent of the milk of humans and some primates.

Question 17

how is fat found in milk

Answer 17

Fat is present in milk in the form of membrane-enveloped fat globules
Milk is an oil-in-water emulsion where the fat is present in tiny droplets within the water phase

Question 18

what is the oil-in-water emulsion in milk stabilized by

Answer 18

The oil-in-water emulsion is stabilized by milk proteins

Question 19

how much cholesterol is found in the globular fat membrane

Answer 19

Cholesterol is a minor component of the globular membrane accounting for two percent of the membrane

Question 20

how many fatty acids are found in milk fat? where is it derived from?

Answer 20

Milk fat contains about four hundred different fatty acids derived from the animals’ feed, microbial fermentation in the rumen and de novo synthesis in the mammary gland

Question 21

what is the fat content of milk and the distribution of fatty acid types affected by

Answer 21

genetic, physiological and environmental factors including breed, stage of lactation, milking frequency, feed, season, and health status.

Individual animal variation in amounts and types of fat also exists. Ratios between different types of fats show seasonal variation, the proportion of unsaturated fatty acids is higher in the summer and, consequently, the melting point is lower.

Question 22

what properties of milk does fat affect

Answer 22

Milk fats affect the texture and flavour of dairy products; they provide the smooth oral sensation derived from drinking milk and they serve as a reservoir for other flavour compounds providing the buttery taste of milk

Question 23

what nutritional benefits do fats have

Answer 23

They are an excellent source of energy and a carrier for the fat-soluble vitamins A, D, E and K

Question 24

how much fat concentration is found in milk

Answer 24

Total fat content of cow milk can range from 1.8 to 6 percent although it typically constitutes four to five percent of the milk

Question 25

what western breeds of dairy cows have the highest and lowest concentrations of fat in their milk

Answer 25

Relative to other western dairy breeds, the Holstein cow has the lowest percentage fat in its milk and the Jersey cow has the highest

Question 26

what breed would make more fat in the milk in a lifetime jersey or holstein

Answer 26

because of its much higher milk yield, the Holstein cow actually produces more fat than the Jersey

Question 27

how much can milk fat percentage range per species

Answer 27

Differences between species show that the fat content of milk can range from less than one percent (donkey, black rhinoceros) to more than sixty percent (hooded seal)

Question 28

what two proteins are found in milk

Answer 28

particulate casein in micelles and soluble whey (serum) proteins

Question 29

how much percent of protein doe caseins make up

Answer 29

Caseins make up eighty percent of milk proteins

Question 30

what are the characteristics of the protein casein? what is the pH? what production does caseins make milk good for?

Answer 30

The caseins are heat-stable phosphoprotein particles that precipitate from milk at a pH of 4.6 or after treatment with rennin or chymosin; this property is integral to cheese-making

Question 31

what is whey protein

Answer 31

Whey proteins are dissolved in the serum phase of milk and are comprised of a variety of proteins including enzymes, antibodies and mineral binding proteins

Question 32

what are the two different types of whey protein

Answer 32

Two major whey proteins are β-lactoglobulin and α-lactoalbumin

Question 33

of the two different types of whey protein what one causes the most allergic reaction

Answer 33

both of these have been known to cause allergic reactions in persons consuming whey proteins. Of the two, β-lactoglobulin is the more allergenic

Question 34

how can whey be denatured

Answer 34

The whey proteins are easily denatured by heat.

Question 35

what does the mineral component of milk include

Answer 35

milk includes ash (potassium, sodium, calcium, magnesium and phosphorus) and milk salts (calcium, magnesium, sodium and potassium salts of phosphate, citrate, acetate, chloride and carbonate)

Question 36

what form can milk salts be found in

Answer 36

Milk salts may be present in both soluble and insoluble forms

Question 37

how many minerals are found in milk

Answer 37

All 22 essential minerals for humans are present in raw milk.

Question 38

what vitamins are found in raw milk

Answer 38

Vitamins found in raw milk include the fat-soluble vitamins A, D, E and K and the water-soluble B vitamins and vitamin C

Question 39

why is Vitamin fortification of drinking milk is mandatory

Answer 39

because vitamins present in raw milk are lost during fat separation

Question 40

how can milk from other species be consumed

Answer 40

they may be consumed as liquid milk or used to manufacture specialty cheeses

Question 41

what are some other species used to produce milk

Answer 41

Some of the other species used to produce milk for human consumption are water buffalo, goats, sheep, horses, camels, reindeer, and moose

Question 42

what criteria do milking animals need to meet

Answer 42

Milking animals need to be tame enough to not be a danger to milk and produce sufficient milk to make milking them worthwhile

Question 43

why would moose milk be so expensive

Answer 43

Moose milk is an expensive commodity, perhaps because of the dangers associated with milking a moose

Question 44

how much of the worlds milk comes from cows

Answer 44

Cows are the source of more than eighty percent of the world’s milk

Question 45

how much of the worlds milk comes from water buffalo

Answer 45

about fifteen percent of milk production comes from water buffalos

Question 46

how much of the world’s milk comes from goats and sheep

Answer 46

goats and sheep produce three percent

Question 47

where does most milk come from in developing countries

Answer 47

Almost a third of the milk in developing countries comes from water buffalos, goats, sheep, and camels

Question 48

where does most of the milk come from in developed countries

Answer 48

practically all of the milk in developed countries comes from cattle

Question 49

how can milk from different species differ

Answer 49

Milks from different species differ significantly in fat, protein and lactose content

Question 50

what are most of the milk consumed in north america

Answer 50

The majority of milk consumed in North America is cow’s milk. Goat’s milk occupies a relatively small niche market although goat milk cheeses are fairly common, There are also some specialty sheep milk cheeses available. More specialized and expensive cheeses have been made from moose milk, donkey milk and pig milk.

Question 51

how is milk different then other foods

Answer 51

Milk is the one product we consume that is designed only to be a food

Question 52

how much protein does a 250ml glass of milk contain

Answer 52

A single 250 ml glass of milk will supply almost half of the protein requirements of a five- to six-year-old child. It has great potential to balance dietary requirements of low income people