Comparison of aroma compounds in naturally fermented and inoculated Chinese soybean pastes by GC-MS and GC-Olfactometry analysis

The industrial fermentation of Chinese soybean pastes has the advantages of high production efficiency and quality consistency. However, the aroma of the current industrial products (with inoculation) is often less satisfactory than the naturally fermented products. In this study, the volatile compounds of natural fermented and inoculated Chinese soybean pastes were evaluated and compared. Results showed that the natural fermented samples had higher contents of volatiles than the inoculated samples, and seven volatile compounds were identified as aroma active compounds for natural fermented sample including 4-hydroxy-2(or 5)-ethyl-5(or 2)-methyl-3(2H)-furanone, ethyl linoleate, 2,3-butanediol, acetic acid, fufural, benzene acetaldehyde and pyrazine 2,6-dimethyl. The inoculated sample had lower sensations of soy sauce, grease, yeast culture and osmanthus, and higher sensations of burning, sourness and cooked rice than the natural fermented samples. Further research is needed to elucidate the effects of raw materials, microbial community and processing conditions on the generation of aromas of fermented Chinese soybean pastes. (C) 2010 Elsevier Ltd. All rights reserved.