Milk Flashcards
What are the three ‘phases’ of milk?
Stable- fat globules
Colloidal- casein micelles and why protein
True- soluble minerals (lactose and water)
What is casein comprised of?
Alpha, beta and K-caseins in a ratio of 60:40:10
Are alpha and beta caseins phosphoproteins or glycoproteins?
Phosphoproteins
Are K-caseins phosphoproteins or glycoproteins?
glycoproteins
what makes milk white?
calcium phosphate
- caseins self assemble into casein micelles which remain in close association with calcium phosphate which makes milk white
outline the importance of casein
it is dispersed in water to carry calcium
it is the dominant protein in bovine milk
name the methods by which casein can be separated in milk
skimmed milk powder acid casein rennet casein casein ate milk protein concentrate phospchocasein
what is skimmed milk powder (SMP)?
- fat is removed via centrifugation
- milk is pasteurised, evaporated and spray dried, which produces a powder that is 35% protein
- can be used for UHT
what is acid casein?
- produces yoghurt
- changes pH from 6.7 to 4.6 using HCl, sulphuric acid and lactobacillus which concentrates caseins and eliminates lactose, whey and minerals that are soluble at a low pH
- water washing facilities casein before it is pasteurised and dried
what does acid casein produce?
yoghurt
what does rennet casein produce?
cheese
what is rennet casein?
casein- chymosin- whey and curd
what is caseinate?
the neutralisation of acid/ rennet casein through adding alkali
the alkali converts insoluble caseins into casein dispersions which can bind with water, dissolve and rehydrate
sodium hydroxide, calcium hydroxide, ammonium hydroxide and sodium carbonate all increase pH
what is milk protein concentrate (MPC)?
concentration of casein using membrane technology
what is phosphocasein?
concentration of casein using microfiltration
why are milk proteins obtained in powder form?
to prevent spoilage
to store at room temperature
to be used in a range of products
outline the uses of casein-based ingredients
acid gels
- caseinate, phospchocasein and skimmed milk powder
- for use in yoghurt and cream cheese
recombined milk proteins
- skimmed milk powder
- for use in UHT milk
food emulsions
- sodium caseinate, skimmed milk powder
- for use in oil-in-water emulsions (ice cream, mayo)
- for use in water-in-oil emulsions (table spreads)
what is whey
a by product of the manufacture of dairy products
what is beta-lactoglobulin
β-Lactoglobulin is the major whey protein of cow and sheep’s milk- about half the whey in milk
what is alpha-lactalbumin
α-Lactalbumin is a protein occurring in the milk of mammals and is especially high in concentration in human milk
what is caseinomacropeptide
a casein derived glycopeptide
what is immunoglobulin
a globular protein found in blood and mammary glands
what is serum albumin
Serum albumin is a large protein present in human and bovine milk and makes up approximately 10%–15% of total whey protein. It is a source of essential amino acids
what are lactoferrin and lactoperoxidase
milk proteins with antimicrobial activities
name 3 whey protein based ingredients
whey-protein concentrates
whey-protein isolates
whey-protein hydrolysates
how are whey-protein concentrates obtained
ultrafiltration
how are whey-protein isolates obtained
ion exchange separation
how are whey-protein hydrolysates obtained
protein hydrolysis
outline the manufacturing considerations for whey
- effects of heat treatment (e.g. denaturation)
- changes during storage of the dry powder (e.g. Maillard)
- flavour change (e.g bitter flavour)
what are the uses of whey protein
functional
- solubilisers, gelation, foaming, emulsification
nutritional
- infant formulas
- sport nutriton
what are the regulations surrounding whey
ingredients with less than 80% protein are not permitted to be imported to the UK
