Antioxidative and Angiotensin I-Converting Enzyme Inhibitory Activities of Sufu (Fermented Tofu) Extracts

Abstract

Tofuyo and sufu are fermented tofu products which are popular in Okinawa, Japan and in China, respectively. Water extracts from 4 types of tofuyo (produced in Okinawa, Japan) and one type of sufu (produced in Beijing, China) were prepared and their antioxidative activity and angiotensin I-converting enzyme (ACE) inhibitory activity were determined. The sufu extract showed higher antioxidative and ACE inhibitory activities than the 4 tofuyo extracts. There was a positive correlation between the antioxidative activity and ACE inhibitory activity of the extracts from the 5 samples. SDS-PAGE patterns of the extracts indicated that all the extracts mainly consisted of peptides whose molecular weights were less than 10 kDa. Although further investigations on the structure of the peptides in the extracts should be conducted and the relationship between the peptide structure and the 2 activities should be determined, it was shown that sufu contained highly active components and could be used as a functional food.