Optimization of Conditions for Removing Ochratoxin A from Wheat Bran by Biological Fermentation and Evaluation of Volatile Flavor Substances before and after Fermentation

A strain of Aspergillus niger FS-UV-21 with obvious removal effect on ochratoxin A (OTA) was used as a fermentation strain to ferment and detoxify wheat bran contaminated by OTA. Taking the removal rate of OTA as the index, the effects of fermentation time, temperature, inoculation amount and solid-liquid ratio on the removal effect of OTA were studied, and the solid-state fermentation conditions of wheat bran were optimized by response surface methodology. At the same time, the volatile flavor compounds of wheat bran before and after fermentation under the optimal fermentation conditions were analyzed and evaluated. The results showed that under the conditions of inoculation amount of 15%, fermentation temperature of 32 ℃, fermentation time of 5 d and feed water ratio of 1:3.3 g/mL, the highest removal rate of OTA was 60.89%. The relative error with the theoretical value was 2.65%, which showed that the optimized parameter was feasible and had practical application value. The flavor substances before and after fermentation were studied by headspace solid phase microextraction and GC-MS. It was found that volatile compounds increased significantly after fermentation, including a variety of substances with unique flavor, such as nonanol, vanillin, and so on. This study provides technical support for the safe utilization of wheat bran.