Bioactive peptides and lactic fermentations

Milk proteins contain regions within their primary structures that encrypt for many latent biological activities. The beneficial health effects associated with some fermented dairy products may, in part, be attributed to the release of bioactive peptide sequences during the fermentation process. Peptides displaying opioid, mineral binding, cytomodulatory and hypotensive activities, for example, have been identified in cheese and yogurt. Much effort has to date concentrated on the release of angiotensin-converting enzyme (ACE) inhibitory peptides due to their potential to act as hypotensive agents. Peptide fractions obtained by hydrophobic interaction chromatography of different cheese varieties (Blue, Camembert, Edam, Emmental, Gouda and Havarti) were reported to give systolic blood pressure (SBP) decreases in spontaneously hypertensive rats (SHR) ranging from 7.1 to 29.3 mm mercury (Hg). Skim milks fermented with various strains of Lactobacillus helveticus, and in one case also with Saccharomyces cerevisiae, have been reported to display SBP decreases in mildly hypertensive human volunteers ranging from 4.6 to 14.1 mmHg. These human hypotensive effects have, in part, been attributed to the release of potent casein-derived tripeptide inhibitors of ACE during fermentation. In general, the likelihood of any bioactive peptide released during fermentation mediating a physiological response is dependent on the ability of that peptide to reach an appropriate target site. Therefore, peptides may need to be resistant to further degradation by gastrointestinal and serum proteinases/peptidases following oral ingestion in order to display a functional food effect.