Mycotoxins reduction in dawadawa (an African fermented condiment) produced from Bambara groundnut (Vigna subterranea)

Abstract

Fermentation has been recognized as a viable food technique that contributes to food safety, enhances nutritional composition and health promoting properties of food. In this study, fermentation time (48–120 h) and temperature (25–45 °C) were optimized during the production of unhulled and dehulled dawadawa from Bambara groundnut, and mycotoxin reduction therein was investigated. Results showed that increasing fermentation conditions (time and temperature) led to an increase in pH and titratable acidity, which slightly decreased after prolonged fermentation period. Liquid chromatography-tandem mass spectrometry analysis of mycotoxins showed a significant (p ≤ 0.05) reduction of mycotoxins after fermentation. A 100% reduction in aflatoxin B1 (AFB1), aflatoxin G1 (AFG1), fumonisin B1 (FB1), fumonisin B2 (FB2), ochratoxin A (OTA), T2-toxin (T2), alpha-zearalenol (α-ZOL) and beta-zearalenol (β-ZOL) was achieved in dehulled samples. An increase in fermentation time and temperature was also observed to have led to greater mycotoxin reduction. This reduction was much higher in dehulled dawadawa compared to unhulled dawadawa samples. In conclusion, the selected optimal fermentation conditions (120 h 35 °C for UHD and 84 h 35 °C for DD) for dawadawa production were obtained from higher values for pH and TTA while this comparably corresponds with mycotoxin reduction. This study demonstrates that dehulling Bambara groundnut together with fermentation to produce dawadawa can effectively reduce mycotoxins, ensuring the safety of this frequently used condiment.