Antifungal activity of gaseous allyl, benzyl and phenyl isothiocyanate in vitro and their use for fumonisins reduction in bread

Fumonisins (FBs) are toxins produced mainly by the molds Fusarium verticillioides (synonym Fusarium moniliforme) and Fusarium proliferatum. These mycotoxins are contaminants of wheat, maize, maize-based foods and other grains worldwide. FB1, the most abundant and toxic metabolite, is known to cause a range of species-specific toxic responses. It has been associated with a high incidence of esophageal cancer in the Transkei region of South Africa and some provinces of China. In addition, FB1 has been declared a class 2B carcinogen or “possibly carcinogenic to humans”. Isothiocyanates (ITCs) are natural compounds produced by enzymatic conversion of metabolites called glucosinolates. They are potentially useful antimicrobial compounds for food applications. In this study, the reduction of the FBs present in loaf bread contaminated with Gibberella moniliformis CECT 2987, a fumonisin producer by allyl (AITC), phenyl (PITC) and benzyl isothiocyanates (BITC) was investigated. In addition, the antifungal activity of these ITCs toward Fusarium mycotoxigenic strains was also evaluated. The ITCs employed in this study inhibited the growth of three mycotoxigenic Fusarium, reducing 2.1–89.7% of the mycelium size. The ITCs used also reacted with the FB2 produced by G. moniliformis in the bread, reducing its levels by 73–100% depending on the dose and time of exposure.