β-Casein variants differently affect bulk milk mineral content, protein composition, and technological traits

Detailed milk protein composition has strong influence on milk quality. This study quantitatively investigated the effect of β-casein variants A1, A2 and B on composition, and technological traits of bulk milk. A total of 171 commercial herds located in northern and central Italy were visited, and 299 bulk milk samples were collected. Traditional milk quality traits, major minerals, milk coagulation properties were assessed. Detailed milk protein composition and β-casein genetic variants were determined by reversed-phase HPLC. Effects of β-casein variants were estimated by fitting a mixed model with variants concentration as a covariate. Results demonstrated that greater concentration of β-casein B is linked with greater protein, casein, and fat content. Likewise, greater concentration of variants A1 and B of β-casein had a significant positive effect on rennet coagulation time and curd firmness, and was linked to a greater amount of Ca and P content than was the A2 variant.