Variability in the levels of fungicide residues in final beer as they are influenced by various sequences of agrochemicals used for treatment on hops.

The fate of during brewing of pesticides (organic compounds and copper) from hops was determined to reveal linkages between various pesticide sequences applied in hop yards and the level of pesticides in beer. For this purpose, laboratory-scale brewing trials were carried out with conventional hops from four localities in which pest control spray programs varied. Pesticide residue analysis in samples of hopped wort, young beer, and beer was carried out by liquid chromatography in tandem with mass spectrometry (LC-MS/MS). Cu concentrations were determined using inductively coupled plasma mass spectrometry (ICP-MS). The transfer rates (%) of individual pesticides were calculated to demonstrate their ability to be transferred from hops to the brewed solutions. The pesticides exhibited different transfer rates correlating well with their log p values; however, the obtained transfer data were not related to their concentration in hops. The average transfer rates calculated for ametoctradin (15% ± 5%), mandipropamid (38% ± 4%), boscalid (48% ± 5%), and azoxystrobin (47% ± 2%) increased in good correlation with their descending log P values. On the contrary, the transfer rates of copper residues were related to residual concentrations of copper in hops and exhibited logarithmic dependency. The carryover of the sum of all pesticides in the four samples ranged from 36% to 49%, averaging 42% ± 6%. The data showed no substantial influence of various pesticide spray sequences on the percentages of overall pesticide residues carried over into beer.

Seasonal and geographical variations in insecticide and miticide residues in hop samples produced across three hop-growing regions in the Czech Republic during the years 2018-2020.

The aim of this study was to determine the presence of zoocide (insecticide and miticide) residues in hops collected in three hop-growing regions located in the Czech Republic, and to assess their zoocide profiles and residue levels in terms of variability in temperature and precipitation across the 2018-2020 seasons. Furthermore, the weather factors that influenced the occurrence of hop pests are described and discussed. During our 3-year survey, a total of 120 samples of whole-cone hops samples harvested in three hop-growing regions were analysed for the presence of 29 insecticides and miticides using the modified QuEChERS extraction method, followed by liquid chromatography-tandem mass spectrometry and gas chromatography-tandem mass spectrometry. A majority, 119 of 120 samples, contained a residue of at least one of the active substances surveyed in this study, and 34 analysed samples contained multiple residues with three to four zoocides presented. Concerning the most frequently detected zoocide residues, spirotetramat and/or its metabolites were found in 94.2% of the samples at levels ranging from 0.02 to 1.08 mg/kg. Of the other zoocides surveyed, residues of fenpyroximate, hexythiazox, bifenazate and lambda-cyhalothrin were routinely found in hop cone samples. Obtained data were then used for evaluating seasonal and geographical variations in the profile of zoocide residues among the hop-growing regions in the years 2018-2020, and the compliance with legal regulations concerning the use of zoocides on hops was ascertained. The results showed that (1) the profile and levels of zoocide residues found in the samples reflected seasonal prevalence of pest infestation on hop plants; (2) the strategy to control pests (especially aphids) used in most of hop yards was consistent across the seasons; and (3) a concentration of spirotetramat residues less than 1 mg/kg was typical for hops grown in the Czech Republic.

Fate and Behavior of Field-Applied Pesticides during Malting and Mashing Processes.

The present work aimed to study the fate of field-applied pesticides during malting and mashing processes. Twenty-four field-collected barley samples were subject to micromalting followed by lab-scale mashing to investigate the carryover of residual pesticides from barley to malt and then from malt to sweet wort. The citrate-buffered QuEChERS sample preparation method was adapted for simultaneous determination of 57 pesticide residues in grain, malt, spent grains, and sweet wort samples using ultra-performance liquid chromatography coupled with tandem mass spectroscopy (UPLC-MS/MS). Residues of four fungicides (fenpropimorph, pyraclostrobin, tebuconazole, and trifloxystrobin) and two insecticides (chlorpyrifos and pirimiphos-methyl), frequently found in the barley samples, were investigated in detail in this study. The carryover percentages of these pesticides to malt, against the concentration of residues in barley grain, ranged from 22% for pirimiphos-methyl up to 78% for fenpropimorph. The results confirm a general rule that residues of pesticides with log P values >2 remain on the malt, but it was found that their transfer potential is more related to its individual physical-chemical properties but does not much correlate to their log P values. In the second part of the study, a noticeable carryover from malt to sweet wort was observed for pyraclostrobin, fenpropimorph, and tebuconazole residues, and these values ranged from 2 to 15%. Moreover, the analysis of pesticide residues in spent grain after mashing revealed that the spent grain samples contain on average once as much pyraclostrobin and tebuconazole residues as the original malt. It was concluded that (1) pyraclostrobin and tebuconazole residues could be incorporated into or associated with macromolecules in barley grain to form "hidden" (bound) forms, and (2) the parent compounds are subsequently released from their hidden forms during mashing.

Tracking, Behavior and Fate of 58 Pesticides Originated from Hops during Beer Brewing.

The study presents tracking of 58 pesticide residues associated with hops to estimate their carryover into brewed beer. The pesticides were spiked onto organic hops at a concentration of 15 mg/kg, and the wort was boiled with the artificially contaminated hops and fermented on a laboratory scale. Samples were collected during the whole brewing process and pesticide residues were extracted using a method known as QuEChERS (quick, easy, cheap, effective, rugged, and safe). An HPLC-HR-MS/MS method was developed and validated to identify and quantitate pesticide residues in treated hops, spent hops, hopped wort, green beer, and beer samples. Quantitation was achieved using standard addition with isotopically labeled standards. The carryover percentages into hopped wort and the percentages of decay reduction relative to the amount spiked on hops were calculated. The relationship between the partition coefficients n-octanol-water (log P values) and the residual ratios ( RW and RB) of a pesticide were evaluated to predict their behavior during hopping of wort and fermentation. Pesticides with a high log P values (>3.75) tended to remain in spent hops. The pesticides that have a low log P value up to approximately 3 could represent the demarcation lines of appreciable transfer rate of pesticides from hops to beer. Consequently, the pesticides were divided into three categories depending upon their fate during the brewing process. The most potential risk category represents a group involving the thermostable pesticides, such as azoxystrobin, boscalid, dimethomorph, flonicamid, imidacloprid, mandipropamid, myclobutanil, and thiamethoxam, which were transferred at high rates from the pesticide enriched hops into beer during the laboratory brewing trial. These results can be used as a guideline in the application of pesticides on hop plants that would reduce the level of pesticide residues in beer and their exposure in humans.

A novel approach for identification of biologically active phenolic compounds in complex matrices using hybrid quadrupole-orbitrap mass spectrometer: A promising tool for testing antimicrobial activity of hops.

The phenolic compounds, secondary metabolites of hops represent a large family of compounds that could be subsequently divided into smaller groups based on the similarities between their chemical structures. The antibacterial, antifungal and antiviral properties of hops are well known, but there is a lack of information about antimicrobial activities of individual hop compounds. This study was carried out with an objective to identify compounds present in hops that have potential antibacterial activity. In the first stage of experiment, the active compounds with potential anti-microbial activity had to be extracted from hop cones. Therefore, minced hop cones were applied on solid growth medium inoculated with Staphylococcus aureus. The active substances that migrated into the medium created an inhibition zone. In the second stage of experiment, the inhibition zones were cut out from Petri dishes, active compounds were extracted from these zones and consequently analyzed using LC-HRMS. These complex assays were developed and optimized. The data were acquired by using a quadrupole-orbitrap hybrid mass spectrometer by targeted-MS2 experiment in both ionization modes. The MS method has been developed as a screening method with a subsequent fragmentation of compound of interest on the base of inclusion mass list. The unknown compounds extracted from inhibition zones have been identified either by searching against a database or their structure has been elucidated on the basis of their fragmentation spectra. On the basis of this experiment the list of active compounds with potential anti-microbial activities was enhanced.