Recent advances in the bovine 13-casein gene mutants on functional characteristics and nutritional health of dairy products: Status, challenges, and prospects

13-casein is the second most abundant form of casein in milk. Changes in amino acid sequence at specific positions in the primary structure of 13-casein in milk will produce gene mutations that affect the physicochemical properties of dairy products and the hydrolysis site of digestive enzymes. The screening method of 13-casein allele frequency detection in dairy products also has attracted the extensive attention of scientists and farmers. The A1 and A2 13-casein is the two usual mutation types, distinguished by histidine and proline at position 67 in the peptide chain. This paper summarizes the effects of A1 and A2 13-casein on the physicochemical properties of dairy products and evaluates the effects on human health, and the genotyping methods were also concluded. Impressively, this review presents possible future opportunities and challenges for the promising field of A2 13-casein, providing a valuable reference for the development of the functional dairy market.