Influence of β-casein genotype on physicochemical properties and functionality of bovine milk

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 A₁ and A₂, for which cows may be homozygous or heterozygous. In this study, several physicochemical properties of milk with β-casein variants A₁A₁, A₁A₂, and A₂A₂ from 3 collection occasions were analyzed. Higher manganese content and lower pH were found to be associated with the A₁A₁ variant compared with the other 2 genotypes. Better rennet and acid coagulation were found in A₁A₁ milk compared with A₁A₂ and A₂A₂ milk (although P > 0.05), whereas A₂A₂ 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 A₁A₁ genotype could be preferable for cheese making, while that with A₂A₂ variant can be used in formulations requiring good stability against creaming, and for example, yogurt making, where the softer yogurt texture may be easier to digest.