Abstract: A comparison was performed of the flavor characteristics of three raw sauces fermented from rice dregs by pure and mixed starter cultures and raw soy sauce fermented by a pure starter culture in order to clarify the effects of cofermentation of Aspergillus oryzae with Zygosaccharomyces rouxii or Lactobacillus plantarum on sauce flavor. The results showed that the free amino acid content, taste active value (TAV), and the number and amount of volatile flavor components in raw soy sauce and raw rice dreg sauce fermented with mixed starter cultures were significantly higher than those of rice dreg sauce fermented with pure Aspergillus oryzae culture. Especially, the relative content of 4-vinylguaiacol in rice dreg sauce co-fermented with Aspergillus oryzae and Z. rouxii reached 9.71%. The results of electronic tongue showed that the principal components of four kinds of raw sauce differed obviously. The flavor of rice dreg sauce co-fermented with Z. rouxii was similar to that of soy sauce, both of which had good umami and weak sourness. Rice dreg sauce co-fermented with L. plantarum had a well-balanced taste and the best overall sensory quality. There were differences in overall flavor between rice dreg sauce and soybean sauce, but the optimized mixed culture fermentation significantly enhanced the flavor of rice dreg sauce.

Key words: rice dreg, soybean, raw sauce, electronic tongue, flavor