Impact of in vitro static digestion method on the release of β-casomorphin-7 from bovine milk and cheeses with A1 or A2 β-casein phenotypes

Abstract

Beta-casomorphin-7 (BCM7) represents the fragment Val⁶⁰-Ile⁶⁶ of bovine β-casein (β-CN), and there is evidence that it is more easily released during gastrointestinal digestion (GID) of A1 β-CN variant, in comparison to the A2 variant. This study aimed at investigating the effect of type of enzymes and the protease/protein (P/S) ratio on BCM7 release during the intestinal step of in vitro static GID of bovine milk and cheeses with A1 or A2 β-CN phenotypes. BCM7 occurred in digests of both A1 and A2 samples, being the release more marked for A1 counterparts. Nonetheless, the BCM7 release depended on both the type of GID enzymes and the P/S ratio. These findings highlight the importance of GID conditions which may affect the outcomes for possible differences between A1 and A2 milk based on BCM7 release during in vitro GID.

Keywords: A1 and A2 bovine β-casein; Cheese; In vitro static gastrointestinal digestion; Milk; β-Casomorphin-7.