The toxicity and decreased concentration of aflatoxin B<inf>1</inf> in natural lactic acid fermented maize meal

Aims: Aflatoxin B1 (AFB1) is a mycotoxin which is known to frequently contaminate poorly stored food products destined for human consumption. This study was carried out to investigate the potential activity of lactic acid fermentation in reducing AFB1 level in fermented maize meal products. Methods and Results: Maize meal was spiked with 60 μg g -1 AFB1 and fermented, with or without starter culture, for 4 days at 25°C. Unbound AFB1 in solution and the pH of the media were monitored daily. A significant decrease (P < 0.05) in the level of unbound AFB1 was observed (75% in the fourth day). Simultaneously, a progressive decrease in the pH of the media from 6.5 to 3.1 was also observed. AFB1 was below the detection limit in commercial fermented porridge (amahewu) samples. Cytotoxicity tests on AFB1-spiked fermented extracts showed that those with a starter culture were comparatively less toxic (30-36%) than those with no added starter culture (24-30%). However, this difference was not significant (P > 0.05). Conclusions: These results indicate that lactic acid fermentation can significantly reduce the concentration of AFB1 in maize to trace levels. However, the safety of fermented products has not been well studied, as the mechanism of AFB 1 removal is not well understood. Significance and Impact of the Study: Natural fermentation may potentially reduce exposure to natural toxins occurring in food. © 2006 The Society for Applied Microbiology.