Adsorption of aflatoxin B1 mycotoxins by raw and lyophilized bentonitic clay

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• Raw and lyophilized polycationic bentonite for AFB 1 adsorption; • AFB 1 removal capacity above 90% for all studied samples; • Optimal conditions obtained for lower temperature and longer freezing time; • Liophilization does not change the cation exchange and adsorption capacities; Aflatoxin B1 (AFB 1 ) is considered the most toxic mycotoxin with the greatest potential for contamination of animal feed. Among the most promising and practical approaches to reducing aflatoxicosis is the addition of non-nutritive adsorbent materials to contaminated food intended for animal feed, such as natural or modified bentonitic clays. The lyophilization process, when compared to other means of dehydration, maintains the product's integrity and characteristics such as contraction, loss of volatiles, thermal decomposition, enzymatic actions, and protein denaturation. The objective of this work was to evaluate the AFB 1 adsorption capacity by raw bentonite and samples submitted to different lyophilization parameters. Statistical design was applied to identify the best freezing parameter for the lyophilized sample in the adsorption of AFB 1 . Possible structural alterations were evaluated by X-ray fluorescence (FRX), X-ray diffractometry (XRD), BET analysis, moisture content, swelling and cation exchange capacity (CEC). AFB 1 adsorption was carried out applying 0.5% of the sample as anti-mycotoxin additive to gastric juice and intestinal juice by the ELISA enzyme-linked immunosorbent assay and by high-performance liquid chromatography (HPLC). The optimal treatment condition was obtained for 150 g of bentonite and 72 h of freezing for the tested temperature range (−75 °C to −90 °C). After freezing, it was observed a reduction of 46% in moisture content, 47% in surface area and 7.12% in total porosity when compared to the standard material. The removal capacity obtained in vitro assays for AFB 1 was above 90% for all samples at pH 3.0 and pH 6.0, being considered promising values for future applications of bentonite as anti-mycotoxin additive.