Effect of household cooking on aflatoxin B 1 migration in black beans: insights from bio-accessibility and intestinal transport

Household cooking is widely considered an effective strategy to reduce mycotoxin contamination in legumes; however, its impact on gastro-intestinal fate and actual dietary exposure remains unclear. This study evaluated the impact of domestic cooking on aflatoxin B1 (AFB1) levels in black beans (a cultivar of the common bean, Phaseolus vulgaris L.), integrating bio-accessibility and intestinal transport to assess potential exposure. Naturally contaminated beans were subjected to soaking and pressure cooking under conditions defined by a 22 Central Composite Rotational Design. Cooking reduced AFB1 levels by 80-93% with optimal conditions for 50 g beans soaked for 8 h and then cooked with 841 mL water. Estimated daily exposure ranged from 0.186 to 0.541 ng kg−1 body weight day−1, based on consumption of cooked grain. Bio-accessibility was low when calculated relative to raw beans (6.9–35.1%) but exceeded 100% relative to cooked samples, indicating the release of matrix-associated or previously non-extractable toxin during digestion. However, only 30.4% of the bio-accessible fraction permeated the membrane, indicating limited potential for absorption. These findings demonstrate that reductions observed after processing may not reflect actual exposure, highlighting the importance of integrating gastrointestinal fate into mycotoxin risk assessment.