Occurrence and biotransformation of ochratoxin a during pepper sauce fermentation

Gochujang, a savory and pungent fermented sauce, is a Korean ethnic food composed primarily of fermented soybean cake, red pepper powder, glutinous rice, and salt. Industrial gochujang is fermented following inoculation with Aspergillus oryzae and Bacillus subtilis as starter microorganisms. In contrast, a wide variety of natural fungi and bacteria are used in fermentation and aging of artisanal gochujang, the aging period of which is longer than 6 months. We monitored ochratoxin A (OTA) contamination of red pepper and gochujang available in the Korean retail market and explored the possibility that microorganisms in gochujang might degrade OTA present in contaminated red pepper during soybean fermentation and aging. We report here that OTA can be easily biotransformed serially to several products by B. Subtilis (KTCT 1021) under the conditions of our experiments. The dynamic microbial activity in gochujang might contribute to the low occurrence of ochratoxin A in this product despite the use of highly contaminated pepper powder, one of the main ingredients of gochujang. At the same time, however, an inappropriate fermentation process and the long aging period are assumed to be sources of contamination. Studies to identify critical control points and to prevent fungal spoilage by the development of high quality starters should be followed up to enable the artisan to produce OTAfree gochujang.