Bioaccessibility in daily diet and bioavailability in vitro of aflatoxins from maize after cooking

Bioavailability is not a constant percentage of a contaminant in food but is affected by many factors, such as food type, treatment, diet structure and interaction with other compounds. To evaluate these influences, we measured the bioaccessibility of aflatoxins from nine naturally polluted maize samples, collected from southeast China, using an in vitro digestion model, and analysed the intestinal transport of aflatoxins by a Caco-2 cell model. Steam cooking treatment could reduce the aflatoxin levels in maize bread. The degradation rates of aflatoxin B-1, aflatoxin B-2, aflatoxin G(1), and aflatoxin G(2) ranged from 24.9 +/- 3.2 to 33.9 +/- 3.5%, 27.0 +/- 2.0 to 39.0 +/- 1.8%, 27.9 +/- 7.9 to 34.4 +/- 8.2% and 25.6 +/- 3.6 to 37.2 +/- 6.5%, respectively. As a result, the bioaccessibility of aflatoxins determined by an in vitro digestion model (41.5-63.3%) was much lower than the previously reported 80%. Edible oil could increase the bioaccessibility of aflatoxin, whereas lettuce would decrease the exposure amount from maize. With a Caco-2 cell model, the apparent permeability coefficient exceeding 10-5 cm/s indicated that there is high absorption of aflatoxins in the human body, while the intestinal transport can be effectively restrained in the presence of chlorophyll.