Identification of β-casein phenotypes (A1/A2) in the milk of the Indian Jersey crossbreed bovine using the high-resolution accurate mass spectrometer

Foodomics is an emerging probing method of phenotype investigation of the different milk proteins and their subtypes. The polymorphic nature of the beta-casein (beta-Cn) protein has shown fourteen different protein variants to date in bovines. The analysis of the beta-Cn genetic polymorphism from the milk of the crossbred dairy animals is crucial for the quality assurance of the consumers from the various health concerns, especially those linked with the A1 phenotype which yields beta-casomorphin-7 on in vivo digestion. Jersey-crossed Indian cattle have been widely utilised in dairy because of their better milk production and survival performance trait. In this investigation, an SDS-PAGE coupled with a high-resolution accurate mass spectrometry-based proteomics approach has been applied to identify the presence of specific phenotype of the beta-Cn protein in the milk of the 24 Indian crossbred (Jersey crossed) animals. Amino acid sequential analysis has been done using different search modules, as MS Amanda and Sequest HT showed 17 cows are producing A(2) beta-Cn (Pro-67) while only seven animals yielded the A(1) variant (His-67). The maximum number of Indian Jersey-crossed animals are lactating milk having A(2) beta-Cn. The A(2) milk from the crossbred animals is free from the negative impact on health caused by beta-casomorphin-7 (BCM-7) released during digestion of the A(1) phenotype. Among the molecular biology techniques, top-down proteomics has been an intriguing technique for the identification of protein genetic polymorphic products.