Inactivation Mechanisms of Different Mycotoxins

Abstract

Mycotoxins can be inhibited at three strategic phases. During synthesis: by inhibiting the growth of producer strains and inhibiting the synthesis of mycotoxins. During processing: by physical separation, chemical inactivation and biological inactivation. During consumption: by alteration of bioavailability and modification of toxicity. Unquestionably, prevention of mycotoxin production is the best method for controlling mycotoxin contamination. Should the contamination occur, the hazard associated with the toxin must be removed if the product is to be used for food or feed purposes. Mycotoxins often occur in crops in the field prior to harvest. Physical separation on the field is the best choice to decrease the level of contamination. Enzymatic inactivation of fungal toxins is a beneficial strategy for the decontamination of agricultural commodities and for the protection of crops from phytotoxic effects of fungal metabolites. Natural compounds like ajowan, garlic and turmeric all have decreasing activity of mycotoxins. Microbial metabolites like aflastatin A (AsA), produced by A.parasiticus a novel inhibitor of aflatoxin production on melanin biosynthesis of Colletotrichum lage-narium was reported. Some toxin-producing fungi are able to degrade or transform their own products to non toxic forms under suitable conditions. Studies suggest that certain fungi, including A. parasitic us, degrade aflatoxins, possibly through fungal peroxidases. Fermentation with yeasts has also been effective in destroying patulin and rubratoxin B. Many of the studies have involved Lactobacillus strains, and physical binding has been proposed as one mechanism of mutagen removal. Sulfhydryl (thiol) compounds such as cysteine, N-acetylcysteine, reduced glutathione, and mercaptopropionylglycine interact with disulfide bonds of plant protease inhibitors and lectins via: sulfhydryl-disulfide interchange and oxidation-reduction reactions. Studies have shown that the major reaction product formed from the reaction of aflatoxin B-1 with ammonium hydroxide at elevated temperature and pressure has lacked the lactone group characteristics of aflatoxin B1 which has no toxic activity.