Influence of β-casein genotype on physicochemical properties and functionality of bovine milk
Nan Gai, T. Uniacke‐Lowe, J. O’Regan, David Goulding, Alan L. Kelly
Abstract
Several studies have been focused on the effect of milk protein genetic variants on milk physicochemical properties and functionality in recent years. β-casein, an important protein related to milk processibility, has been reported to have 2 main genetic variants A 1 and A 2, for which cows may be homozygous or heterozygous. In this study, several physicochemical properties of milk with β-casein variants A 1 A 1 , A 1 A 2 and A 2 A 2 from 3 collection occasions were analyzed. Higher manganese content and lower pH were found to be associated with the A 1 A 1 variant compared with the other 2 genotypes. Better rennet and acid coagulation were found in A 1 A 1 milk compared with A 1 A 2 and A 2 A 2 milk (although P > 0.05), while A 2 A 2 milk was more stable to creaming compared with the other 2 genotypes, which may be linked to its smaller fat globule size. Thus, milk from cows with A 1 A 1 genotype could be preferable for cheese making, while that with A 2 A 2 variant can be used in formulations requiring good stability against creaming, and for, e.g., yogurt making, where the softer yogurt texture may be easier to digest.