Influences of fermentation and ripening temperatures on the enzymatic activity and physicochemical and sensory properties of salted egg white sufu

Abstract

This study developed a novel form of sufu. Salted egg white sufu (SEWS) was produced by fermenting steamed salted egg white with douchi koji and ripening at 25°C, 35°C, or 45°C for 19 days. The results show that the protease activity of the koji reduced pronouncedly during fermentation, whereas the one in the SEWS initially increased but subsequently decreased. The total nitrogen and amino nitrogen contents and degree of protein hydrolysis increased during fermentation and decreased during preripening. SEWS, particularly processed at 35°C, contained more free amino acids, notably glutamic acid and leucine, than steamed salted egg white did. After processing, SEWS had darker colors, particularly when manufactured at higher temperatures, and hardness and springiness decreased. The 35°C and 45°C SEWS had higher sensory acceptability. In conclusion, ripening at 35°C for 19 days is recommended for producing this novel animal protein-based sufu.