Fermentation of wort containing added ochratoxin A and fumonisins B1 and B2.

Ochratoxin A (OA), fumonisin B1 (FB1) and fumonisin B2 (FB2) were added to wort at levels of 0.19, 0.95 and 0.95 micrograms/ml, respectively, and fermented for up to 8 days by three strains of Saccharomyces cerevisiae. Decreases of OA in the beer over this period were estimated from straight line slopes to be 2-13%. Losses of FB1 and FB2 were estimated to be 3-28% and 9-17% respectively. Some OA was taken up by the yeast, up to 21% in a detailed study with one strain. In contrast, uptake of fumonisins by yeast was negligible (< 1% FB1 and < 2% FB2). In control experiments, OA, FB1 and FB2 were found to be stable when added to yeast-free wort and kept for up to 8 days at 25 degrees C. In addition, spiking experiments with blank day 0-8 fermenting wort samples showed method recoveries averaging 87-91%. None of the mycotoxins was detected in control fermentations where they were not added to the wort.