Thesis (BS Food Technology) -- University of the Philippines Mindanao, 2009

The ACE inhibitory activities of amahong, dayok and sisi hydrolysates were investigated. The specific ACE inhibitory activity of amahong was 27.12%; sisi's activity was 23.39% and dayok's activity was 17.57%. Specific ACE inhibitory activities of amahong and sisi were not significantly different from each other. From these samples, sisi was chosen for monitoring peptide inhibitory activity during the stages of fermentation. During fermentation of sisi, peptide content and ACE inhibitory activity generally increased. Degree of hydrolysis correlated with the ACE inhibitory activity. ACE inhibitory activity of the heat-treated oyster extract also exhibited ACE inhibitory activity of 8.87% per mg peptide. However, the activity is still lower than that of the fermented oyster. Further, the hydrolysates from oyster were subjected to in vitro hydrolysis by gastrointestinal proteases to investigate their inhibitory activity during gastric digestion. It was found out that their inhibitory activities increased after these were treated with proteases indicating liberation of stronger ACE inhibitory peptides from these hydrolysates during gastric digestion. Moreover, the specific ACE inhibitory activity of the heat-treated oyster residue was the highest among the three. This means that in vitro gastrointestinal digestion and not fermentation was the predominant factor controlling the formation of ACE inhibitory activity.