Impact of heat-treated Lactobacillus helveticus on bioactive peptides in low-fat, semi-hard cheese.

Lactobacillus helveticus cultures are used to accelerate ripening of cheddar and semi-hard cheese varieties, and an important effect is increased peptide breakdown. This work was made to investigate the impact on bioactive peptides in low-fat, semi-hard cheese of heat treated Lb. helveticus CNRZ 303. The dominating HPLC peaks of the peptide profiles representing mainly histidine rich, basic and potentially antioxidative peptides from the amino end of α S1 -casein were hydrolysed by Lb. helveticus enzymes. Phosphopeptides, which may have a role in mineral uptake in human nutrition, were also hydrolysed by Lb. helveticus enzymes into smaller phosphopeptides, however, all the groups of serine-P were still intact, and no change in content of inorganic P occurred during two months of ripening. Potential antihypertensive activity because of ACE inhibiting peptides increased during ripening, however, there was no further effect of adding Lb. helveticus. By simulation of gastrointestinal proteolysis of cheese by using commercial enzymes, ACE inhibition of the soluble fractions increased significantly and much more than it did during ripening.