Preliminary assessment of bioaccessibility of aflatoxin B1 in fish

Bioaccessibility of aflatoxin B-1 (AFB(1)) found in contaminated peanut meal was assessed by an in vitro system that simulated conditions of Nile tilapia (Oreochromis niloticus) intestine. Peanut meal containing 17.1 mu g kg(-1) AFB(1) was used as substrate. Reference assays were carried out with intestinal enzyme extracts from adult tilapia under realistic physiological conditions of enzyme/substrate ratio (0.21 U mg(-1)), pH (8.2), and temperature (25 degrees C). Different factors that could potentially affect bioaccessibility of AFB(1) were evaluated: total digestion time (3 to 6 h), relative amount of substrate (250 to 750 mg), and amount of rice husk used as adsorbent (1:1 and 1:2, peanut meal/rice husk). AFB(1) released after digestive hydrolysis was extracted by QuEChERS and quantified by a multi-reader. Bioaccessibility of AFB(1) increased with digestion time (from 36 after 3 h to 100% after 6 h) and with the amount of substrate. In contrast, rice husk reduced bioaccessibility of AFB(1) by 28 and 20% in ratios of 1:1 and 1:2, respectively. Therefore, this study suggests not only that in vitro assays may be used as prospective assays to evaluate bioaccessibility of AFB(1) under species-specific digestive conditions, but also that inclusion of rice rusk in feed may be a promising tool to reduce mycotoxin bioaccessibility.