a b s t r a c tNumerous studies have focused on the effects of food-processing techniques on pesticide residues. However, it remains a challenge to ensure high-quality processing and effective pesticide removal from foods. Triadimefon (TF) is a broad-spectrum fungicide that is widely used in barley crop, and its residues are detected in its products, including beer. In this study, we investigated the dissipation kinetics of TF during fermentation mediated by two different yeast strains, Saccharomyces cerevisiae IAPPST 1401 (Y1) and CICC 1202 (Y2), and found that Y2 promoted the degradation of TF. Response surface methodology was used to optimize fermentation process variables, in order to achieve the maximum removal rate of TF and the minimum production of its corresponding metabolite, triadimenol (TN). Processing factors (PFs) were also evaluated during the optimized brewing process and were close to 1 for TF during the malting, milling, boiling, and cooling steps, but not in mashing and fermentation that were 0.19 and 0.13, respectively. TF degraded to TN during brewing, and a PF value of >1 for TN was also observed in malting and fermentation. Our analysis concluded that beers produced using the yeasts and brewing methods we investigated are safe for human consumption.

Despite the fact that beer is produced on a large scale, the effects of pesticide residues on beer have been rarely investigated. In this study, we used micro-brewing settings to determine the effect of triadimefon on the growth of Saccharomyces cerevisiae and beer flavor. The yeast growth in medium was significantly inhibited (45%) at concentrations higher than 5 mg L−1, reaching 80% and 100% inhibition at 10 mg L−1 and 50 mg L−1, respectively. There were significant differences in sensory quality between beer samples fermented with and without triadimefon based on data obtained with an electronic tongue and nose. Such an effect was most likely underlain by changes in yeast fermentation activity, including decreased utilization of maltotriose and most amino acids, reduced production of isobutyl and isoamyl alcohols, and increased ethyl acetate content in the fungicide treated samples. Furthermore, yeast metabolic profiling by phenotype microarray and UPLC/TOF-MS showed that triadimefon caused significant changes in the metabolism of glutathione, phenylalanine and sphingolipids, and in sterol biosynthesis. Thus, triadimefon negatively affects beer sensory qualities by influencing the metabolic activity of S. cerevisiae during fermentation, emphasizing the necessity of stricter control over fungicide residues in brewing by the food industry.

a b s t r a c tThe behavior and fate of 3 pesticides (triadimefon, malathion, and dichlorvos) and the main metabolites (triadimenol and malaoxon) during barley storage or beer processing were assessed using a pilot-plant equipment. The residues of all products were determined using liquid chromatography coupled with tandem mass spectrometry. Field investigation of the dissipation rate kinetics for triadimefon and malathion during storage indicated that their half-life was twice as high when 5 times the recommended dosage was used. Milling had little effect on the removal of dichlorvos and malathion residues, whereas these were substantially removed when the spent grains were filtered after mashing. The calculated processing factors were all <1, indicating the residual ratios of dichlorvos and malathion were reduced during the entire process. In conclusion, storage and processing considerably reduced pesticide residue levels in barley and beer; however, greater focus needs to be paid to the toxicity of their metabolites in commercial by-products.