Effects of Processing and NaCl on Angiotensin I-Converting Enzyme Inhibitory Activity and γ-Aminobutyric Acid Content During Sufu Manufacturing

Abstract

In the present study, sufu, the cheese-like, traditional fermented soybean food from China, was prepared by solid-state fungal fermentation and ripened in dressing mixtures with different NaCl content. The angiotensin I-converting enzyme (ACE) inhibitory activity and γ-aminobutyric acid (GABA) content were determined during sufu manufacturing. The influence of NaCl on ACE inhibitory activity and GABA content was also investigated. The ACE inhibitory activity and GABA content of sufu were significantly affected by processing and NaCl content. During fermentation, the ACE inhibitory activity percentage increased from 11.55 to 37.61 %, whereas the GABA content increased from 32.64 to 133.13 mg/100 g dry matter. The salting process caused a decrease in both. Generally, the ACE inhibitory activity and GABA content increased during ripening. The ACE inhibitory activity at the same ripening interval was inhibited by NaCl. After ripening for 8 weeks, the sufu samples with 5 % NaCl had the highest ACE inhibitory activity, with an IC50 of 0.79 mg/mL, whereas the samples with 8 % NaCl had the highest GABA content at 193.5 mg/100 g dry matter. A significant correlation was found between ACE inhibitory activity and peptide content. These results indicated that sufu could be useful in alleviating hypertension because it contained ACE inhibitors and GABA as antihypertensive substances. Low NaCl content could increase the antihypertensive activity.