Fate of agrochemical residues, associated with malt and hops, during brewing

A process for predicting the potential for persistence of agrochemical resi due levels in beer has been developed. For this, we first developed analyti cal methods for determining the agrochemical residues in beer, wort, and va rious by-products during the brewing processes. Second. various types of ag rochemicals were spiked during the mashing, wort boiling, or fermentation p rocesses and the residues in the product and in the by-product were determi ned with the developed method. Agrochemicals added were representative of t he typical chemical groups of agrochemicals for which maximum residual leve ls in barley or hops are regulated by Japanese official law. Third, the pot ential for the carryover of agrochemical residues into wort and beer was in vestigated based on their chemical properties such as thermostability, chem ical reactivity, and oil/water solubility (which was expressed as log P-ow values). It was found that the carryover of agrochemical residues into wort and beer depended on their log P-ow values. The carryover percentages into wort or beer of glyphosate (organophosphorus herbicide) having the lowest log P-ow value were more than 90% of the amount added to each process. On t he other hand, most of the agrochemicals having a high log P-ow value, such as pyrethroid pesticides, were detected in the fractions of the spent grai ns and spent hops. Some amounts of the added agrochemicals were lost during the wort boiling process. On the other hand, no significant reduction was observed during the fermentation process. None of the agrochemicals spiked in the hop pellets were detected in beer because of the loss during boiling and fermentation, though the levels of the spiked agrochemicals were high enough to be detected in beer if no loss of the spiked agrochemicals had oc curred. From these results, the process for predicting the potential for th e carryover of agrochemical residues in malt or hops into beer on a laborat ory scale was proposed, in that the log P-ow values of a agrochemical was e ffectively used as the primary indicator.