Release of β-casomorphin-7 from bovine milk of different β-casein variants after ex vivo gastrointestinal digestion

The release of β-casomorphin-7 (BCM-7) in bovine milk with β-casein genetic variants A1, A2, F and I was assessed. An ex vivo gastrointestinal (GI) digestion model was applied and multiple reaction monitoring method for quantification of BCM-7 was set up using Triple-Q LC-ESI-MS specifically for the BCM-7 peptide. BCM-7 was released after digestion of milk of all variants, although with large differences in concentration between variants. Higher amounts of BCM-7 were found from milk samples of the A1 family (A1 and F) with 1.85-3.28 mg g−1 β-CN digested, whereas the A2 family (A2 and I) only released 0.01-0.06 mg g−1 β-CN digested. Compared with earlier findings on digestion of purified β-CN, this study showed larger differences in quantified BCM-7 between different milk types, potentially due to the different matrixes of the milk. However, all β-CN variants A1, A2, F and I released BCM-7 after GI digestion.