milk proteins- Week 8

Question 1

what are the 3 different phases of milk & what do each contain

Answer 1

1)stable emulsion (containing fat)
2)Colloidal suspension (containing all proteins: whey & casein)
3)true solution(contanning rest of the nutrients, e.g. lactose, minerals, water)

Question 2

what is casein

Answer 2

casein is composed of alpha, beta (are phosphoproteins) and k-casein proteins (are glycoproteins which are more hydrophobic)

Question 3

explain what casein micelles is

Answer 3

what is the name of when casein self-assemble into protein packets

Question 4

what gives milk its white colour

Answer 4

alpha and beta caseins are held together by hydrophobic interactions & k-caseins remain at the surface- this provides a REPULSIVE STERIC FORCE between individual micelles

Question 5

what are the importance of caseins in the food industry

Answer 5

-it dispenses in water & carries a large amount of calcium
-dairy industry has the capability of separating these proteins which gives us other ingredients

Question 6

what are the casein-based ingredients (6)

Answer 6

-Skimmed milk powder
-Acid casein
-Rennet casein
-Caseinate
-Milk protein concentrates
-Phosphocasein
(All products are obtained as powder)

Question 7

what is the benefit of all the casein-based ingredients being powder

Answer 7

-they are dry so will be preserved for a longer time

Question 8

what is skimmed milk powder (SMP) uses and applications

Answer 8

SMP is soluble following reconstitution (with water they reconstitute and can be used for any other product) & can be used for further processing like UHT
-RECOMBNED MILK PRODUCTS- due to stability at high temp
-CHOCOLATE- milk chocolate may be composed of SMP and whey proteins
-BAKERY- SMP and whole milk powders are used

Question 9

what is Acid casein uses and applications

Answer 9

it’s the preliminary step in the production of yogurt
-acid gels (yogurts and cream cheese)

Question 10

what is the difference between skimmed milk powder and acidic casein

Answer 10

SMP has the whey proteins and casein whereas acid casein only has casein proteins

Question 11

what is the uses/applications of Rennet casein

Answer 11

-preliminary step in production of cheese
-CHEESE ANALOUGE

Question 12

what is the method to obtain phosphocasein as a caseinate-based ingredient

Answer 12

its the concentration of casein by using microfiltration

Question 13

what is the method to obtain Milk protein concentrates (MPC) as a caseinate-based ingredient

Answer 13

concentration of casein by membrane technology

Question 14

what is the method to obtain Caseinate as a caseinate based ingredient

Answer 14

neutralisation of acid/rennet casein through addition of alkali

Question 15

what are the uses/applications of caseinate

Answer 15

for sodium and calcium caseinate the use/application is ACID GELS
-FOOD EMULSIONS (both types of emulsions, oil-in-water emulsions like mayonnaise and ice-cream & water-in-oil emulsions like table spreads)

Question 16

what are the uses/applications of Phosphocasein

Answer 16

ACID GELS(like cream cheese and yogurt)

Question 17

what is whey

Answer 17

its a by-product of the manufacture of dairy products, particularly cheese

Question 18

what are the 3 most important whey proteins

Answer 18

Beta-lactoglobulin
alpha-lactalbumin
Glycomacropeptides

Question 19

what are the whey protein-based ingredients

Answer 19

-whey protein concentrates
-whey protein isolates
-whey hydrolysis

Question 20

how are whey protein concentrates obtained

Answer 20

ULTRAFILTRATION to remove water, lactose and minerals

Question 21

how are whey protein isolated obtained

Answer 21

ION EXCHANGE SEPARATION- washes out the lactose, minerals & caseinomacropeptide

Question 22

how are whey proteins hydrolysed

Answer 22

proteins are exposed to hydrolysis by incubating proteolytic enzymes at elevated temperatures

Question 23

what are the functional properties of the whey protein ingredients (4)

Answer 23

1)SOLUBILIZERS
2)GELATION: formation of gels when heated at conc above 10%
3)FOAMING; formation of aerated foods
4)EMULSIFICATION: oil-in-water emulsions

Question 24

what are the nutritional properties of whey proteins & explain each one (2)

Answer 24

1)INFANT FORMULATIONS: hydrolysis breaks down possible allergenic proteins
2)SPORTS NUTRION: high levels of branches amino acid chains which are preferably metabolised by muscle rather than liver & sport drinks & nutrition bars