Contents of agonistic and antagonistic opioid peptides in different cheese varieties

Two opioid peptides with agonistic (β-casomorphin-5 and β-casomorphin-7) and three with antagonistic (casoxin-6, casoxin-C and lactoferroxin A) activity were determined in three semi-hard cheeses (Edamski, Gouda and Kasztelan) and in two ripening mould cheeses (Brie and Rokpol). β-Casomorphins (BCMs) were found at a higher level in the mould cheeses, whereas the opioid peptides with antagonistic activity were identified at a higher level in the semi-hard cheeses. The opioid activities of the peptide extracts from the cheeses were confirmed using isolated rabbit ileum.