Abstract: The hardness, chewiness, elasticity, cohesiveness, color, amino acid nitrogen content and cellulose activity of naturally fermented Shuidouchi made from soybeans grown in southwestern China’s Chongqing and northeastern China were measured at different stages of the fermentation process. The relationship between amino acid nitrogen content and color parameters and hardness was determined using regression analysis. The results showed that during the fermentation process consistent changes were observed in hardness and chewiness. The largest decrease in hardness occurred during the soaking and cooking processes. The trends of cohesiveness and elasticity were consistent, both of which were only slightly changed during soaking and cooking. The elasticity decreased during post-fermentation process. The L value decreased first rapidly and then tended to be stable, and the color gradually became darker. The a and b values remarkably increased, and the color turned into yellow and red. As a result, Shuidouchi formed its unique yellow or yellowish-brown color. Regression analysis revealed that the content of amino acid nitrogen was negatively correlated with the L value but positively correlated with the a and b values. The L value was the most correlation with the content of amino acid nitrogen, and for Shuidouchi made from Chongqing-grown and northeastern China-grown soybeans, the correlations were 74.5% and 86.3%, respectively. Accordingly, it was suggested that the L and a values could be used to predict the amino acid nitrogen content of Shuidouchi. Chongqing-grown soybean was more suitable for the processing of Shuidouchi.

Key words: Shuidouchi, texture, color, changing pattern