Novel process may enhance the flavor and quality of soy sauce, say scientists

Chinese researchers report that a novel two-step inoculation process with Candida etchellsii may increase the level of soy sauce flavor compounds by as much as 180%.

Writing in the International Journal of Food Science & Technology, researchers from Jiangnan University report that their two-step process could “elevate the special flavor and quality of the soy sauce”.

“This [simple, reproducible and optimized] process described in our study has been proven to be a feasible reproducible process for industrial application for the improvement of the flavor and quality of soy sauce production,” they wrote.

There are numerous types of soy sauce varieties with many Asian countries producing their own version of the condiment.

According to background information in the new paper, the conventional production method for soy sauce involves an initial fermentation of soybeans by Aspergillus species followed by a brine fermentation process’ with salt-tolerant lactic-acid bacteria (Tetragenococcus halophila) and yeasts such as Zygosaccharomyces rouxii and Candida versatilis.

In an attempt to improve the flavor and quality of soy sauce the Jiangnan University researchers investigated the potential of a two-step process with different levels of C. etchellsii yeast.

The first-stage was inoculation with a 5% culture of the yeast for 30 days, and the second phase was 20% culture inoculum added after 60 days.

Analysis of the resulting soy sauce revealed that levels of the typical soy sauce flavor compounds 4-ethyl-guaiacyl phenol and 4-hydroxy-2 (or 5)-ethyl-5 (or 2)-methyl-3 (2H)-furanone (HEMF) increased by 176% and 161%, respectively.

Source: International Journal of Food Science & Technology
October 2012, Volume 47, Issue 10, pages 2072–2078, DOI: 10.1111/j.1365-2621.2012.03071.x
“A two-step inoculation of Candida etchellsii to enhance soy sauce flavour and quality”
Authors: J. Feng, X-B. Zhan, Z-Y. Zheng, D. Wang, L-M. Zhang, C-C. Lin