Comparison of aflatoxins and ochratoxin A contaminated in homemade and commercial doenjang manufactured by traditional and modified methods

Doenjang, a soybean-based fermented food that is traditionally consumed in Korea, is vulnerable to contamination by mycotoxins, such as aflatoxins (AFs) and ochratoxin A (OTA), during the fermentation process. In this study, a novel accurate high-performance liquid chromatography with fluorescence detector (HPLC-FLD) method was validated for rapid and simultaneous detection of AFs and OTA levels in doenjang. The HPLC-FLD method performs well in terms of sensitivity, selectivity, accuracy, and precision, with detection range of 0.03–0.13 μg/kg and quantification range of 0.10–0.40 μg/kg for AFs and OTA. The validated method was applied to 134 homemade and 157 commercial doenjang samples manufactured in Korea using both traditional (spontaneous fermentation-based) and modified (starter culture-based) methods. AFs and OTA were detected in 13.1% (0.16–273.35 μg/kg) and 28.5% (0.56–46.29 μg/kg) of the doenjang samples, respectively. There were no significant differences in the contamination rate or mean concentration between the homemade and commercial doenjang. By contrast, doenjang manufactured using the modified method exhibited significantly (p < 0.05) lower contamination rates and levels of AFs and OTA compared with those produced using traditional methods. The risk of exposure to AFs and OTA through consumption of doenjang manufactured by different methods was estimated by the margin of exposure approach and revealed that the health risk for Korean was lower in doenjang manufactured by modified method, regardless of homemade or commercial products. Thus, the use of selected fermentation starters for the modified method can reduce contamination by AFs and OTA in doenjang, whether manufactured at domestic or industry level. These findings are expected to improve the safety management of mycotoxin contamination in doenjang and similar soybean-based fermented foods.