Module 7-what is milk? Flashcards
what is milk
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)
what nutrient groups does milk include? how digestible is it?
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.
what is milk made up of
Milk is made up of water, lactose, fat, protein and ash (minerals)
what is the most variable component of milk
The most variable component is fat
is the major carbohydrate of milk
lactose
where is lactose mostly found
it is found almost exclusively in milk
what is lactose
Lactose is a disaccharide sugar derived from galactose and glucose; its systematic name is β-D-galactopyranosyl-(1->4)-D-glucose
what is lactose designed for
Lactose is an energy source for young animals
who cannot break down lactose
individuals who are lactose intolerant
what is lactase
The enzyme that breaks down lactose
where is lactase produced
lactase is normally produced by the small intestine
what does lactase break lactose into? where is it absorbed?
it breaks lactose down into glucose and galactose which are absorbed from the small intestine
what happens in the digestion of lactose in a lactase intolerant person
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
how does lactose impact the properties of milk
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
how much lactose is in cows milk
Lactose constitutes four to five percent of cow’s milk
Lactose constitutes four to five percent of cow’s milk how does this compare to other mammals
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.
how is fat found in milk
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
what is the oil-in-water emulsion in milk stabilized by
The oil-in-water emulsion is stabilized by milk proteins
how much cholesterol is found in the globular fat membrane
Cholesterol is a minor component of the globular membrane accounting for two percent of the membrane
how many fatty acids are found in milk fat? where is it derived from?
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
what is the fat content of milk and the distribution of fatty acid types affected by
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.
what properties of milk does fat affect
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
what nutritional benefits do fats have
They are an excellent source of energy and a carrier for the fat-soluble vitamins A, D, E and K
how much fat concentration is found in milk
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
what western breeds of dairy cows have the highest and lowest concentrations of fat in their milk
Relative to other western dairy breeds, the Holstein cow has the lowest percentage fat in its milk and the Jersey cow has the highest
what breed would make more fat in the milk in a lifetime jersey or holstein
because of its much higher milk yield, the Holstein cow actually produces more fat than the Jersey
how much can milk fat percentage range per species
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)
what two proteins are found in milk
particulate casein in micelles and soluble whey (serum) proteins
how much percent of protein doe caseins make up
Caseins make up eighty percent of milk proteins
what are the characteristics of the protein casein? what is the pH? what production does caseins make milk good for?
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
what is whey protein
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
what are the two different types of whey protein
Two major whey proteins are β-lactoglobulin and α-lactoalbumin
of the two different types of whey protein what one causes the most allergic reaction
both of these have been known to cause allergic reactions in persons consuming whey proteins. Of the two, β-lactoglobulin is the more allergenic
how can whey be denatured
The whey proteins are easily denatured by heat.
what does the mineral component of milk include
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)
what form can milk salts be found in
Milk salts may be present in both soluble and insoluble forms
how many minerals are found in milk
All 22 essential minerals for humans are present in raw milk.
what vitamins are found in raw milk
Vitamins found in raw milk include the fat-soluble vitamins A, D, E and K and the water-soluble B vitamins and vitamin C
why is Vitamin fortification of drinking milk is mandatory
because vitamins present in raw milk are lost during fat separation
how can milk from other species be consumed
they may be consumed as liquid milk or used to manufacture specialty cheeses
what are some other species used to produce milk
Some of the other species used to produce milk for human consumption are water buffalo, goats, sheep, horses, camels, reindeer, and moose
what criteria do milking animals need to meet
Milking animals need to be tame enough to not be a danger to milk and produce sufficient milk to make milking them worthwhile
why would moose milk be so expensive
Moose milk is an expensive commodity, perhaps because of the dangers associated with milking a moose
how much of the worlds milk comes from cows
Cows are the source of more than eighty percent of the world’s milk
how much of the worlds milk comes from water buffalo
about fifteen percent of milk production comes from water buffalos
how much of the world’s milk comes from goats and sheep
goats and sheep produce three percent
where does most milk come from in developing countries
Almost a third of the milk in developing countries comes from water buffalos, goats, sheep, and camels
where does most of the milk come from in developed countries
practically all of the milk in developed countries comes from cattle
how can milk from different species differ
Milks from different species differ significantly in fat, protein and lactose content
what are most of the milk consumed in north america
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.
how is milk different then other foods
Milk is the one product we consume that is designed only to be a food
how much protein does a 250ml glass of milk contain
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
