Comparison of flavor profiles of Cantonese soy sauces obtained at different fermentation stages

In this study, we analyzed the differences, including organic acid, free amino acid, and volatile compound contents, in soy sauces obtained at different fermentation stages (stage A, Touyou; stage B, Eryou; stage C, Sanyou). The result showed that the content of total organic acids in Eryou (400.41 mg/kg) and Sanyou (393.95 mg/kg) was significantly higher than that in Touyou (376.52 mk/kg), even though lactic acid content showed no significant differences, which was the dominant organic acid among the three soy sauces. However, the total free amino acid content of Touyou (7.73 g/kg) was significantly higher than that of Eryou (5.82 g/kg) and Sanyou (6.44 g/kg). Moreover, the umami and bitter free amino acid contents in Touyou were significantly higher than those in Eryou (p < 0.50). Besides, Touyou and Sanyou showed the highest peak intensities of alcohols (130157.08) and acids (77943.05), respectively. PLS-DA showed that the soy sauces from different fermentation stages were well separated from each other based on the volatile compounds, and 19 volatile components were selected characteristic volatile compounds with VIP > 1. Thus, these differences in organic acid, free amino acid and volatile compound contents resulted in the variability in flavor and quality of Cantonese soy sauces at different fermentation stages.