Comparison of Functional Components and Antioxidant Activities of Soy Sauces Brewed with Different Raw Materials

Using black bean, soybean and soybean meal as raw materials, soy sauce was prepared by high-salt dilution method. The quality indexes, functional components and antioxidant activities of the three soy sauce were detected by conventional methods and liquid chromatography-mass spectrometry (LC-MS/MS), and the correlation between antioxidant activities and functional components was analyzed. Partial least squares discriminant analysis (PLS-DA) was performed based on the functional components of soy sauce. The results showed that the sensory and physicochemical indexes of the three kinds of soy sauce all met the requirements of the first grade soy sauce in national standard GB 18186-2000 "Brewing Soy Sauce". The functional components of the three kinds of soy sauce (total phenols, total flavonoids, melanoid, total free polyphenols, total free flavonoids, total free amino acids) were 4.78~7.14 mgGAE/mL, 2.75~4.34 mgRE/mL, 1.25%~1.70%, 25.54~35.08 μg/mL, 11.37~20.20 μg/mL, 42.36~48.61 mg/mL, respectively. The antioxidant indexes (total antioxidant capacity, ABTS⁺ and DPPH free radical scavenging rate) were 24.27~605.57 U/mL, 6.43~8.57 mgVCE/mL and 3.53~5.30 mgVCE/mL, respectively. Except for free amino acids, the functional components contents and antioxidant activities of the three kinds of soy sauce were black soy sauce>soybean meal soy sauce>soybean soy sauce, and there were significant differences in antioxidant indexes among the three soy sauce (P<0.05). The correlation results showed that the antioxidant activity of soy sauce was significantly positively correlated with the contents of total polyphenols, total flavonoids and melanoid (P<0.05). PLS-DA results showed that the soy sauce brewed with different raw materials could be distinguished by functional components. In conclusion, the antioxidant activities of soy sauce brewed with different raw materials of different composition and contents of functional components were different, and the functional health effects of soy sauce could be improved by the selection of raw material and enhancement of certain active ingredients.