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In vitro adsorption of aflatoxin B1, ochratoxin A, and zearalenone by micronized grape stems and olive pomace in buffer solutions

Fernandes, Jean-Michel, Calado, Thalita, Guimarães, Ana, Rodrigues, Miguel António Machado, Abrunhosa, Luís
Mycotoxin research 2019 v.35 no.3 pp. 243-252
activated carbon, adsorbents, adsorption, aflatoxin B1, bentonite, byproducts, grapes, ochratoxin A, olive pomace, pH, sorption isotherms, stems, zearalenone
This work characterizes the adsorption of aflatoxin B₁ (AFB₁), ochratoxin A (OTA), and zearalenone (ZEN) by dry micronized olive pomace (OliPom) and grape stems (GrapStem). Their performance was compared with that of three other materials, activated carbon (ActCarb), bentonite (Bent), and a commercial product (ComProd). Experiments were conducted in vitro at several pH values using buffer solutions. For OTA and ZEA, the strongest adsorbent was ActCarb, with 5 mg/mL being sufficient to bind > 99% of all the mycotoxins. For AFB₁, ComProd and Bent were the most effective adsorbents, as 0.5 mg/mL bound > 95% of this mycotoxin. Among the two agro by-products, GrapStem was the strongest binder, with 10 mg/mL being sufficient to bind at least 90% of all the mycotoxins (except OTA at pH 7). OliPom was the least efficient material, but at a concentration of 30 mg/mL, its performance was similar to GrapStem. Adsorption isotherms were calculated, and ActCarb showed the maximum adsorption capacity (Qₘₐₓ), with values that ranged from 19 to 24 μg/mg for pH 2 and from 17 to 20 μg/mg for pH 7. ComProd, Bent, and GrapStem showed more similar Qₘₐₓ between them (1.4–4.4 μg/mg for pH 2 and 0.5–4.8 μg/mg for pH 7).