Angiotensin-converting enzyme inhibitory activity of water-soluble extracts of Asiago d'allevo cheese

The angiotensin-converting enzyme (ACE) inhibitory activity of water-soluble extracts (WSE) from Asiago cheeses was assayed in two cheese production systems and with different ripening times. The WSE were ultrafiltered through 10 kDa and 3 kDa cut-off membranes to evaluate the ACE inhibitory activity of long and short peptides, respectively. The cheese production systems had no significant effect on the ACE inhibitory activity, whereas 6-month-old cheeses had higher inhibitory potency than the more ripened ones. Moreover, the fraction containing peptides smaller than 3 kDa made a more considerable contribution to ACE inhibitory activity than the fraction smaller than 10 kDa, suggesting an inhibitory effect due to short peptides. The peptidic fraction was characterized using RP-HPLC coupled to mass spectrometric detection. Simulated gastrointestinal digestion was carried out to evaluate the effects of digestive enzymes on the generation of bioactive peptides, but this did not significantly affect the inhibitory activity.