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

Abstract

SummaryFoodomics is an emerging probing method of phenotype investigation of the different milk proteins and their subtypes. The polymorphic nature of the β‐casein (β‐Cn) protein has shown fourteen different protein variants to date in bovines. The analysis of the β‐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 β‐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 β‐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 A2 β‐Cn (Pro~67) while only seven animals yielded the A1 variant (His~67). The maximum number of Indian Jersey‐crossed animals are lactating milk having A2 β‐Cn. The A2 milk from the crossbred animals is free from the negative impact on health caused by β‐casomorphin‐7 (BCM‐7) released during digestion of the A1 phenotype. Among the molecular biology techniques, top‐down proteomics has been an intriguing technique for the identification of protein genetic polymorphic products.