Fate of Pesticide Metabolites on Malt during Brewing

Abstract

The fate of fungicidally active metabolites of triadimefon and triflumizole during brewing was studied to estimate their risk of carryover into beer. The water-solubilities of these metabolites, determined from previous studies or a high-performance liquid chromatography retention time index experiment, were greater than those of their parent compounds. This indicated a higher possibility of carryover into beer than that for their parent compounds. A highly sensitive and selective analytical method for the determination of pesticide metabolite residues in wort or beer using liquid chromatography-tandem mass spectrometry (LC-MS/MS) was developed. The metabolites of triadimefon and triflumizole were spiked onto ground malt at a concentration of 1,000 μg/kg. The malt was mashed, and the wort was boiled with hop pellets and fermented on a laboratory scale. The metabolite residues in sweet wort, boiled wort, and young beer were determined. The carryover percentages into sweet wort against the amount spiked on malt were 36% (triadimefon metabolite) and 19% (triflumizole metabolite). These carryovers were close to the calculated levels, expected from their partition coefficients between n-octanol and water (Pow values). The final residues of triadimefon and triflumizole metabolites in young beer were 30 and 7 μg/kg, respectively. These results indicated that the agrochemical metabolites, which have agrochemical activity and toxicity as strong as their parent agrochemicals, persist during brewing and that residues on malt could be carried over into beer like their parent compounds.