Dairy Chemistry And Biochemistry

4 Milk proteins

4.1 Introduction

Normal bovine milk contains about 3.5% protein. The concentration

changes significantly during lactation, especially during the first few days

post-partum (Figure 4.1); the greatest change occurs in the whey protein

fraction (Figure 4.2). The natural function of milk proteins is to supply

young mammals with the essential amino acids required for the develop-

ment of muscular and other protein-containing tissues, and with a number

of biologically active proteins, e.g. immunoglobulins, vitamin-binding,

metal-binding proteins and various protein hormones. The young of differ-

ent species are born at very different states of maturity, and, consequently,

have different nutritional and physiological requirements. These differences

are reflected in the protein content of the milk of the species, which ranges

6

d5

2

8

4

3

0 10 20 30 40 50

Weeks of lactation

Figure 4.1 Changes in the concentrations of lactose (O), fat (0) and protein (0) in bovine
milk during lactation.