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https://efsa.onlinelibrary.wiley.com/doi/pdf/10.2903/sp.efsa.2009.EN-22

Review of mycotoxin-detoxifying agents used as feed additives: mode of action, efficacy and feed/food safety

Prevalence and effects of mycotoxins on poultry health and performance, and recent development in mycotoxin counteracting strategies

Bonding mechanisms between aflatoxin B1 and smectite

Mycotoxins are toxic metabolites produced by several fungi species, with the aflatoxins, fumonisins, zearalenone, trichothecenes and ochratoxin A being the most important found in feedstuffs. The economic impact caused by mycotoxins motivated the investigation of detoxification strategies to reduce its bioavailability by enterosorption. Although there are several types of adsorbents, the efficiency of the adsorption depends on the physical and chemical characteristics of both the adsorbent and the mycotoxin. This review describes the most important types of mineral adsorbents [aluminosilicates, HSCAS, bentonites (montmorillonites), zeolites, sepiolite, diatomite and activated carbons] used in feeds, especially for poultry and pigs, and their adsorption mechanisms.

Mineral adsorbents for prevention of mycotoxins in animal feeds

The study was conducted to characterize and compare twelve different additives distributed in Mexico as mycotoxin binders utilizing: (1) equilibrium isothermal analysis for aflatoxin B(1) (AFB(1)) adsorption, (2) a variety of mineralogical probes, and (3) Hydra toxicity bioassay. The test additives Milbond-TX (MLB), Mycoad (MCA), Volclay FD181 (VOL), Fixat (FXT), Toxinor (TOX), Mexsil (MEX), Mycosil (MYC), Klinsil (KLS), Zeotek (ZEO), Duotek (DUO), Mycosorb (MSB), and Mycofix Plus 3.0 (MIX) were compared with NovaSil Plus (NSP). Isotherms for AFB(1) adsorption were conducted at pH 2 and pH 6.5, mimicking pH conditions in the stomach and small intestine. Mineralogical analysis included determination of swelling volume, X-ray diffraction analysis, and fractionation procedures. A Hydra vulgaris toxicity study was performed to evaluate the potential safety of the additives. Computer-generated isotherm data were fit using the Langmuir model, and parameters of Q(max) and K(d) were estimated. The most effective additives for AFB(1) at both pH conditions were NSP, MLB, MCA and VOL, while the least effective was MSB. The amounts of sand, silt and clay fractions varied among the additives. Nine of the additives showed the presence of smectite. Most of the additives were found to be non-toxic to Hydra except for the organoclays (ZEO, DUO) and MSB. In general, NSP demonstrated the highest sorption capacity in the bulk material and the different fractions. Studies to characterize these binding additives further and to evaluate their multiple mycotoxin sorption claims are ongoing.

In vitro and in vivo characterization of mycotoxin-binding additives used for animal feeds in Mexico

Smectite clay has been shown to sorb aflatoxin B1 (AfB1) in animal feed 2) and thereby reduce its toxic influence on animals and its entrance to the human food chain. In an effort to find effective adsorbents, 39 samples proposed to adsorb aflatoxin were analyzed and classified into four groups based on their properties: coefficient of linear extensibility (COLE), pH, cation exchange capacity (CEC), organic carbon, microbial content and x-ray diffraction (XRD) spacings. A subset of 20 bentonite samples from commercial sources and reference minerals from 6 US-states and 2 sites in Mexico was selected for sorption determinations. A 10-fold difference in sorption based on the Langmuir equation was observed. Yet clay properties were mostly clustered and it is not clear which properties influence this variation. The basal spacing of AfB1 saturated smectites exhibited greater resistance to collapse on heating than untreated smectites indicating that AfB1 entered the interlayer galleries of the smectites. After heating the mycotoxin-clay complex the desorbed mycotoxin was altered indicating a reaction of the molecules with the clay surface. The most effective sorbent smectite samples were from three US-states (MS, ID, TX).

Ines Kannewischer

Papers

Smectite Clays as Adsorbents of Aflatoxin B1: Initial Steps