Changes in Angiotensin I-Converting Enzyme Inhibitory Activities During the Ripening of Douchi (a Chinese Traditional Soybean Product) Fermented by Various Starter Cultures

Angiotensin I-converting enzyme (ACE) inhibitory activities of commercial douchi were determined, and salt-fermented samples were found exhibiting higher activities than dandouchi. Douchi was prepared in laboratory scale by pure culture fermentation. Results showed that ACE inhibitory activity in bacteria-type douchi decreased during maturation, while it increased in fungi-type douchi, with the highest activity observed in Aspergillus oryzae fermented douchi after ripening for 30 days. These suggested that the type of starters affected significantly the generation of ACE inhibitors during douchi ripening. Sensory evaluation showed that A. oryzae produced more organoleptically acceptable douchi than other cultures used in this study.