In vitro assessment of the capacity of certain mycotoxin binders to adsorb some amino acids and water-soluble vitamins

The objective of this study was to evaluate the capacity of 6 mycotoxin binders (MTB) to adsorb 3 AA and 4 water-soluble vitamins (WSV). Two experiments were conducted in in vitro conditions to simulate postruminal digestion with pepsin, malic acid, citric acid, acetic acid, and lactic acid at pH 3.0 and intestinal digestion with bile salts and pancreatin extract at pH 6.5. Experiment 1 was conducted with AA, and experiment 2 was conducted with WSV. Within experiment, main factors were the MTB (bentonite, clinoptiolite, sepiolite, montmorillonite, activated carbon, and yeast cell walls), the substrate (AA: Lys, Met, and Thr; WSV: B1, B2, B3, and B6), and the incubation strategy (substrates alone or mixed). Data were analyzed for the effects of main factors and their interactions. In experiment 1, the adsorption average for AA when incubated separately was 44.3%, ranging from 62.4% for Thr by clinoptiolite to 20.0% for Thr by activated carbon. When incubated together, the average adsorption was reduced to 19.9%, suggesting competition among substrates for adsorption. Adsorption ranged from 29.8% for Thr by yeast cell walls to 5.6% for Met by clinoptiolite, but there were significant interactions among MTB and AA. In experiment 2, the average adsorption of WSV when incubated separately or together was 34.1 and 45.1%, respectively, suggesting possible synergies among substrates. When vitamins were incubated separately, adsorption ranged from 90.5% for vitamin B1 to 4.0% for vitamin B3 by montmorillonite. Vitamins B1 (except by yeast cell walls) and B6 (except by bentonite, sepiolite, and montmorillonite) were absorbed the most, and vitamin B3 was absorbed the least (except by activated carbon and yeast cell walls, which were least together with vitamin B2). When vitamins were incubated together, adsorption ranged from 97.0% for vitamin B1 by montmorillonite to 0% for vitamin B2 by activated carbon and vitamin B3 by bentonite. Vitamins B1 by all MTB and B6 by clinoptiolite, sepiolite, and yeast cell walls were the most adsorbed, and vitamin B3 (except by activated carbon and yeast cell wall) was the least absorbed. There were significant interactions among MTB and WSV. Mycotoxin binders have a high degree of adsorption of the AA and WSV tested in in vitro conditions, which may limit their bioavailability. Results also suggest that when substrates were incubated together some interactions for adsorption occurred, which were competitive among AA and synergic among vitamins.