Dairy products and milk-based food ingredients - Natural Food Additives, Ingredients and Flavourings - page 416

Table 17.2 Fatty acid profi le of milkfat in bovine milk

Fatty acid Weight (%) Common name

4:0 3.32 Butyric acid

6:0 2.34 Caproic acid

8:0 1.19 Caprylic acid

10:0 2.81 Capric acid

12:0 3.39 Lauric acid

14:0 11.41 Myristic acid

14:1 2.63 Myristoleic acid

16:0 29.53 Palmitic acid

16:1 3.38 Palmitoleic acid

18:0 9.84 Stearic acid

18:1 27.39 Oleic acid

18:2 2.78 Linoleic acid

18:3 0.59 Linoleic acid

Source: Kailasapathy (2008).

Table 17.3 Proteins in bovine milk

Component Weight (g/kg)

Total protein 35.1

Total casein 28.6

α s1-casein 11.5

α s2-casein 3.0

β -casein 9.5

κ -casein 3.4

γ -casein 1.2

Whey protein 6.1

α -Lactalbumin 1.2

β -Lactoglobulin 3.1

Proteose-peptones 1.0

Immunoglobulins 0.8

￿ ￿ ￿ ￿ ￿

Serum albumin 0.4

Source: Kailasapathy (2008).

β casein are calcium-sensitive and tend to aggregate at the centre of the casein
micelle. The calcium insensitive κ -casein is found at the surface of micelles,
thereby protecting the other caseins against the precipitating effects of soluble
calcium (Ca 2+ ) ions. Dalgleish (1993) states that the κ -casein peptide sequence
has two distinct regions: the hydrophobic para - κ -casein (amino acid residues
1-105) and the hydrophilic glycomacropeptide (residues 106-169). The
proteolytic enzyme chymosin (commonly termed rennet) used to make cheese
cleaves bovine κ -casein at the Phe 105 -Met 106 junction between para - κ -casein and
the glycomacropeptide, allowing casein to precipitate to form a curd. The
glycomacropeptide is released into the cheese whey.