Assessment of fumonisin B2 contamination in muscadine wine and grape juice as a major risk factor to human healt

Mycotoxins are the secondary metabolites of filamentous fungi. These fungi are ubiquitous in nature and many are known to cause spoilage of agricultural commodities. Fumonisins are mycotoxins that were once thought to only be associated with the Fusarium fungal genera. Currently, Aspergillus niger has also been reported to produce fumonisin B2 (FB2), via the shared fum8 gene. A. niger is a fungal species that thrives in warmer climates and readily produces the FB2 mycotoxin. The environmental conditions that facilitate fumonisin B2 production are also the same conditions required for the growth and maturation of muscadine grapes. The occurrence of mycotoxin contamination of wine and grape beverages within the U.S. has been studied very little. Government guidelines do not address beverages, alcoholic or not, with regard to fumonisin contamination. These published guidelines are only valid for maize and corn products. This study determined that muscadine grapes can serve as a viable substrate for colonization, growth, and subsequent mycotoxin production by A. niger. The stability of this toxin within the white muscadine grape juice matrix was found to be high when stored at three different temperatures (-18, 4, 20°C) over a six month period. Unlike the toxin patulin FB2 did not degrade to concentration safe for human consumption. When surveying the FB2 contamination of commercially available muscadine wines from across the Southeastern U.S., all the sampled wines were found to be contaminated with the toxin. However, the observed toxin levels of these wines were below the provisionary maximum daily tolerable intake of 2mug/kg b.w./day for a 70kg adult set by the FAO/WHO. An assessment of the fate of fumonisin B2 during the production of Noble and Carlos muscadine wine found that juice fermentation played a secondary role in the removal of toxins from artificially contaminated wine. Toxin decontamination was found to be carried out primarily via physical means from the adsorption of the mycotoxin to spent yeast cells. Although this mechanism removed measurable quantities of the toxin, concentration levels still remained beyond the levels for safe consumption.