BCM-7 release from processed dairy products containing measured amounts of beta-casein variants

Beta-casomorphin-7 (BCM-7) is an exogenous opioid released during digestion of A1 beta-casein, but only in small amounts during A2-type beta-casein digestion. We characterized the BCM-7 yield from processed dairy products using a protocol based on a partitioned procedure with LC-MS/MS analysis after proteolytic digestion. Average BCM-7 concentration released from 900 μg of total protein ranged from below the quantitation limit (milk containing only the A2-type beta-casein) to 6.55 mg/g of total beta-casein (hard cheese). Per serving size, yogurt and cheese had the highest BCM-7 yields. A single serving of Lite milk containing only the A2-type beta-casein had negligible BCM-7 yields. There was a strong correlation between BCM-7 yield and A1 beta-casein content. Although the BCM-7 yields from the processed dairy products varied, only the absence or near absence of A1 beta-casein effectively negated BCM-7 release.