Comparison of Flavor Compounds in Soy Sauces Fermented by Two Aspergillus oryzae Strains

The contents of organic acids, amino acids and flavor components in soy sauce fermented by Aspergillus oryzae 3.042 were analyzed by high performance liquid chromatography (HPLC) and gas chromatography-mass spectrometry (GC-MS) in comparison to those of soy sauce fermented by A. oryzae 100-8, a mutant strain. The organic acids, amino acids and flavor components at the end of low-salt solid soy sauce fermentation by A. oryzae 3.042 and 100-8 strains were measured. The content of malic acid in soy paste fermented by A. oryzae 100-8 was increased, while citric acid and succinate were decreased. The contents of asparagic acid, glutamic acid and arginine were increased in fermented koji and soy sauce. The taste of soy sauce was also influenced by different ratios between organic acids and amino acids. The contents of alcohols, aldehydes, acids and pyrazines in soy sauce fermented by A. oryzae 100-8 were enhanced. More pyrazines were detected in soy paste fermented by A. oryzae 100-8. These results seem to provide a theoretical basis for the soy sauce industry.