Winter-type gushing is a beer overfoaming phenomenon that develops gradually during storage and is strongly influenced by storage history. In this study, malt-derived factors contributing to winter-type gushing were investigated with respect to their physicochemical characteristics and contribution to gushing development. Beers brewed exclusively from the endosperm fraction of malt did not exhibit gushing, whereas reproducible gushing occurred when malt husk fractions were included, indicating that gushing-inducing components originate from minor constituents of the husk. Fractionation analyses localized gushing activity to moderately polar husk-derived fractions and demonstrated that the active components were proteinaceous, most likely low-molecular-weight peptide fragments (<= 3 kDa) present in beer. Gushing occurred only in the presence of malt-derived fractions; hop-derived catechin fractions alone did not induce overfoaming, but markedly enhanced gushing intensity when combined with malt-derived components. The dependence of gushing behavior on storage conditions and sample orientation indicates the involvement of physicochemical interactions rather than purely compositional effects. We propose that unstable aggregates formed from malt- and hop-derived components orient at the gas-liquid interface may reduce CO2 dissolution and prolong bubble lifetime, thereby inducing gushing. This study distinguishes essential malt-derived inducers from hop-derived components that enhance gushing.
The stability of hop aroma during storage is a key concern for brewers, yet the relative impact of storage, vintage, and production site on aroma composition remains unclear. This study evaluated Strata (R) hops across multiple harvest years, farms, and fields, focusing on terpene and polyfunctional thiol profiles. While noticeable variability in composition was observed between vintages and sites, particularly for major terpenes and thiols such as 3-sulfanyl-4-methylpentanol (3S4MP) and 4-sulfanyl-4-methylpentan-2-one (4SMP), leading to distinct clusters in multivariate analysis, these within-cultivar differences remained small relative to varietal differences. Storage under typical low-oxygen conditions appeared to have minimal impact on hop aroma and thiol content, whereas elevated oxygen exposure caused notable losses of monoterpenes and 4SMP. These results demonstrate that Strata (R) hops exhibit robust aroma stability during storage, and that environmental and agronomic factors, as reflected by combined farm-field effects, rather than storage duration, are the primary drivers of compositional variability.
Pot ale is a high-volume co-product of whiskey distillation with potential for valorisation. However, its composition varies depending on production processes and source, which may limit its consistent reuse. This study characterised pot ale from three Irish distilleries, analysing total protein, ash content, colour (Lab*), and FTIR spectra. Significant differences were found between sources, particularly in protein and ash levels. Discriminant analysis showed clear grouping by distillery. Biopolymer films produced using the same pot ale samples showed variation in colour and surface properties, while mechanical properties remained comparable across samples. These results highlight that pot ale composition is variable and that this diversity must be accounted for in efforts to develop consistent processing or formulation strategies.
This study investigated the microbiological quality of non-alcoholic draught beers and examined the effect of carbonation on the survival of pathogens, specifically Escherichia coli O157 and Salmonella enterica subsp. enterica serovar Enteritidis. Samples of non-alcoholic draught beers were collected from various outlets across the United Kingdom, while additional data from non-UK beers (United States, Belgium and Spain) were provided by an independent global brewery. One fully carbonated non-alcoholic beer (2.8 v/v) along with its decarbonated variants 1.9, 1.2, 1.0, 0.8 and 0.1 (v/v) were evaluated. Both carbonated and decarbonated versions were tested with and without the addition of sugars (1 g/100 mL of maltose and 0.25 g/100 mL of lactose). Beers were inoculated with three strains of E. coli O157 and Salmonella Enteritidis, and growth and survival were monitored over six months at five time points, in triplicate. Analytical results indicated that the alcohol content in four out of the 90 beers slightly exceeded the regulatory threshold of 0.5% v/v. Overall, 83% of samples tested were classified as microbiologically good or acceptable, while 17% exhibited poor quality, with total aerobic counts exceeding 10,000 CFU/mL. Challenge testing demonstrated that both E. coli and Salmonella were inactivated in fully carbonated beers but were capable of growth in decarbonated and low-carbonated beers. Furthermore, the addition of sugar enhanced survivalof the tested pathogens at specific carbonation levels but increased growth was not observed.
Calibration linearity for beta-myrcene can be the main analytical limitation in HS-SPME-GC-MS (EI-SIM) quantification of selected hop-derived monoterpenes in beer. This study, therefore, evaluated whether extraction temperature could improve simultaneous quantification of beta-myrcene, linalool, geraniol, and beta-citronellol under a single practical workflow. Matrix-matched five-point calibrations were prepared in beer (beta-myrcene and linalool: 0-200 & micro;g/L; geraniol: 0-80 & micro;g/L; beta-citronellol: 0-40 & micro;g/L). After 10-fold dilution and salting-out, analytes were measured at 60, 70, and 80 degrees C by HS-SPME-GC-MS using a 65 & micro;m PDMS/DVB fiber, a DB-WAX UI capillary column, and beta-damascone as the internal standard. Linalool, geraniol, and beta-citronellol remained linear across 60-80 degrees C (R-2 = 0.9920-0.9997), whereas beta-myrcene showed poor linearity at 60-70 degrees C (R-2 = 0.9385-0.9415) but became highly linear at 80 degrees C (R-2 = 0.9992). LOQs (S/N = 10) at 80 degrees C were 0.13 & micro;g/L for beta-myrcene, 0.65 & micro;g/L for linalool, 0.69 & micro;g/L for geraniol, and 0.71 & micro;g/L for beta-citronellol. At 80 degrees C, point-by-point calibration residuals were small, and spike recoveries at 80 degrees C ranged from 96.3% to 101.7%. In 56 commercial beers, all analytes were quantified above LOQ at 80 degrees C; temperature dependence averaged 3-4% (three-point CV) for the oxygenated monoterpenes but 38.2% for beta-myrcene, with average shifts of -37% at 60 degrees C and +40% at 70 degrees C relative to 80 degrees C. These results indicate that, among the tested temperatures, 80 degrees C is the most suitable HS-SPME extraction temperature for routine simultaneous quantification of beta-myrcene, linalool, geraniol, and beta-citronellol in beer under the present workflow.
Accelerating genetic gains in malting barley requires efficient and accurate evaluation of malt quality traits early in the breeding process. However, traditional micro-malting is limited by its high resource demand and large sample requirements. This study assessed the reliability of a low-cost benchtop malting method for determining malt quality metrics on a diverse panel of 45 two-row barley breeding lines and compared the results to those from traditional micro-malting. Significant genotypic variation was observed for all quality parameters. Strong correlations between benchtop and micro-malting methods were found for diastatic power (r = 0.82), total malt protein (r = 0.86), and malt extract (r = 0.77). Free amino nitrogen (r = 0.64), beta-glucan (r = 0.65), and alpha-amylase (r = 0.61) exhibited moderate correlations. Suspecting that some correlations initially scored as "moderate" may have resulted from differences in post-malting analytical protocols rather than the malting methods themselves, a subset of 15 genotypes was reanalyzed using identical post-malting protocols. Increased correlation strength between benchtop and micro-malted was observed for all malt quality parameters. Overall, the benchtop malting system, coupled with plate-reader-based analytical methods, is cost-effective, scalable, and well-suited for early-generation screening of both contemporary and experimental/non-traditional grains, enabling earlier data-driven selection decisions in malting barley breeding pipelines.
Koji has long been used in Japan to supply enzymes, flavors, and nutrients for traditional fermented food and beverages. Its application to brewing offers a unique, versatile, and innovative alternative to specialty malts. This study assessed the brewing suitability of kilned barley koji produced with a barley-koji strain of Aspergillus oryzae-here termed barley koji malts (BKM)-by evaluating the effects of steeping times (6, 7, and 8 h) and solid-state fermentation (SSF) durations (40, 44, and 48 h) on malt quality and metabolomic profiles. BKM exhibited desirable malting quality parameters, including extract levels comparable to standard base malts, rapid production times, and high color formation under a base malt kilning profile. Shorter steeping times yielded improved enzymatic and technological performance, while variation in SSF duration produced distinct color development. This study demonstrates the potential of BKM as a versatile and innovative alternative for specialty malts in craft brewing applications.
Although foam is an important quality parameter of beer, the foam of non-alcoholic beers (NABs) often fails to meet consumer expectations. Because scientific insight into the topic is lacking, this study investigated the differences in foaming properties between NABs and corresponding alcoholic beers (ABs), focusing on the underlying destabilisation mechanisms and associated physicochemical properties. The foam properties of 16 commercial beers were investigated using four foaming methods, including a novel method that allows for foam replenishment. By generating foams with varying (initial) volume, liquid content and lifespan, each test highlighted distinct destabilisation mechanisms and, when combined, offered a more complete understanding of foaming properties. The results confirm that NABs produced by dealcoholisation exhibit significantly reduced foam capacity and stability, resulting in a coarser foam structure compared to ABs. This instability was primarily attributed to a higher rate of coalescence, potentially driven by lower alcohol content and higher surface tension. NABs produced using alternative fermentation exhibited significantly better foam stability than those produced by dealcoholisation, highlighting the possible influence of the NAB production technique. This work provides fundamental knowledge necessary for brewers to create targeted strategies aimed at improving the foam quality of NABs.
Wildfire smoke exposure has emerged as a growing quality concern for hops, yet its impact on beer aroma remains poorly defined. This study evaluated the influence of smoke-related volatile phenols (VPs) on beer quality using sensory thresholds, descriptive analysis, chemical quantification, and brewing trials. Orthonasal detection thresholds for five key VPs (guaiacol, 4-methyl guaiacol, and o-, m-, and p-cresol) ranged from 11 to 140 & micro;g/L, while rejection thresholds varied widely. Cresols were rejected near detection thresholds, whereas guaiacol and 4-methyl guaiacol were tolerated at higher concentrations, indicating compound-specific sensory responses. Descriptive analysis showed guaiacol and 4-methyl guaiacol contributed smoky, woody, and occasionally pleasant attributes (e.g., sweet/vanilla, spice/clove, smoked meat, and BBQ), while cresols were associated with undesirable notes such as medicinal, chemical, Band-Aid, plastic, barnyard, and urine. Brewing trials using smoke-affected and non-affected Citra (R) and Mosaic (R) hops demonstrated that smoke-affected Mosaic (R) produced higher VP concentrations and stronger smoke-related sensory attributes than Citra (R). Although smoke exposure to these hops was not controlled, compositional differences were sufficient to drive clear sensory outcomes. Notably, perceptible smoke aroma occurred even when individual odor activity values were below unity, highlighting limitations of OAV-based predictions. Extraction-rate analysis suggested brewing variables, including hopping regime and yeast, influence VP transfer and expression. Together, these results establish a foundational framework for interpreting smoke-derived volatile phenols in hops and beer and provide actionable insight for evaluating and managing wildfire smoke impacts in brewing applications.
Butyric acid contamination, typically characterized by distinct cheesy or sewage-like odor notes, is a common quality defect in beer. However, the flavor-active compounds causing this defect, their sources and dynamic changes, have not been fully elucidated. In this study, sensory evaluation, gas chromatography-mass spectrometry analysis, and high-throughput genomic sequencing were integrated to provide a comprehensive characterization of the compounds contributing to butyric acid off-flavor in beer and to identify their sources. The results revealed that butyric acid, isovaleric acid, and acetic acid were the primary flavor-active compounds. Clostridium and Bacillus were identified as the dominant bacterial genera, and notably, Clostridium_sensu_stricto was detected for the first time in wort filtration systems and syrup tank rinse water. The wort filtration system, syrup tank, and associated piping networks were determined to be critical control points for butyric acid contamination. Consequently, rigorous sanitation measures and enhanced microbial monitoring in these high-risk areas should be implemented. This study provides a robust theoretical foundation for tracing and preventing butyric acid contamination in the beer industry.
Regional identity is an important factor in hop production, particularly in the Pacific Northwest, where growing environment can impart economically valuable quality traits. Previous studies have documented regional effects on hop chemistry and aroma, but most have been limited to single harvest years, making it difficult to separate persistent regional signals from annual variability. Chemical and sensory properties of Cascade and Mosaic (R) hops grown at 35 locations across Oregon and Washington were evaluated over two consecutive harvest years (2020-2021). A total of 29 chemical and 14 sensory parameters were analyzed using multivariate and univariate statistics. For both varieties, chemical composition showed stronger and more consistent regional structuring than sensory aroma. Harvest year strongly influenced oxygenated terpenes, esters, and related sensory attributes, particularly in Cascade hops, resulting in substantial year-to-year variability within locations. Mosaic (R) hops exhibited greater chemical stability across years, with persistent regional differences primarily associated with hydrocarbon terpenes, total oil content, and hop storage index. Sensory differences were smaller and more variable than chemical differences. Overall, regional identity in hops persists across years but is modulated by annual environmental variation in a variety-dependent manner.
To ensure a high conversion of starch to fermentable sugars and dextrin during mashing, brewers must cope with inherent variability in barley malt properties. In this work, the impact of barley malt starch gelatinization behavior, amylose content, small starch granule volumes, alpha-amylase activity, beta-amylase activity, and limit-dextrinase activity on the starch conversion yield is studied. Forty-two malts (N = 21*2) were characterized and mashed on laboratory scale. Large variations in the starch properties and amylolytic enzyme activities were observed between the malt samples. After mashing, the fermentable sugar yield ranged between 73.5% and 91.3% and the dextrin yield between 8.3% and 20.0%. Partial-least-squares regression models showed a strong negative impact of small starch granule volumes and high gelatinization temperatures on the fermentable sugar yield and maltose production. On the contrary, high amylolytic enzyme activities and amylose contents positively benefited the conversion of starch to fermentable sugars. Opposite effects were observed in the model for dextrin yield. The results suggest considering small starch granule proportions and starch gelatinization behavior when selecting malt for brewing purposes to ensure high fermentable sugar yield after mashing.
Microorganisms were isolated and identified from the artisanal fermented beverages Boj and Suchiles made in Guatemala. The identification of these microorganisms contributes to the character of these local beverages. Bacteria and yeasts were first isolated in specific media and then analyzed using rDNA sequencing and MALDI-TOF MS. The following species were identified in Boj: Saccharomyces cerevisiae, Lacticaseibacillus casei, Lc. paracasei, Lentilactobacillus diolivorans, Schleiferilactobacillus harbinensis, Staphylococcus epidermidis, and Paenibacillus sp., and in Suchiles, the isolated strains were identified as S. cerevisiae, Saccharomycodes ludwigii, Lc. paracasei, Pichia cactophila, Dekkera bruxellensis, D. anomala, Bacillus clausii, B. safensis, Ln. diolorivans, Sch. harbinensis, Ln. parafarraginis, and Acetobacter aceti. The information provided in this study contributes to a deeper understanding of the artisanal beverages Boj and Suchiles. It could serve as a supporting step to the controlled reproduction of these beverages.
Global persimmon production exceeds 5.75 million tons annually. However, the fruit's high moisture content and susceptibility to spoilage present significant economic challenges. This study evaluates the effects of six fining agents-albumin, bentonite, casein, carrageenan, gelatin, and polyvinylpolypyrrolidone (PVPP)-on the quality of persimmon wine. The impacts on clarity, colorimetric properties, soluble protein content, antioxidant activity, and volatile composition were assessed. Albumin markedly enhanced clarity, achieving transmittance levels of 93%-98% after 14 days, whereas PVPP caused the greatest reduction in total phenolic content (27%-34%). PVPP also decreased antioxidant activity by up to 50%, whereas carrageenan preserved or even enhanced antioxidant activity. Volatile analysis showed that bentonite resulted in the largest reduction in total volatile content (up to 22.4%), with significant effects on esters and alcohols. In contrast, albumin increased the total volatile content by 36.6%, primarily due to the increased presence of alcohols and acids. Carrageenan had minimal impact on the volatile profile. These findings suggest that the selective use of fining agents can optimize persimmon wine, enhancing clarity, sensory characteristics, and nutritional value, thus offering a viable strategy for utilizing non-marketable persimmons.
During storage, the quality evolution of strong-flavor baijiu daqu fundamentally shapes the flavor framework of the base baijiu. However, the mechanisms by which daqu storage affects the subsequent fermentation quality remain unclear. To address this, this study integrates physicochemical analysis, flavoromics, and statistical modeling to elucidate the transmission of flavor quality in strong-flavor baijiu. Results showed that during a 1-to-6-month static storage period, the enzymatic activities of daqu (liquefaction, saccharification, and ethanol fermentation capacity) declined. Despite this enzymatic decline, the subsequent solid-state fermentation resulted in flavor enrichment: 17 key esters increased 2- to 3-fold, total esters increased by 35%, and total acidity was regulated to 2.69 g/L. Statistical modeling further revealed that this flavor variation was driven by selective regulatory patterns: initial starch content and acidity were identified as the primary positive drivers for the accumulation of complex long-chain esters, whereas ammonium nitrogen and hydrolytic enzyme activities were more closely associated with the formation of short-chain esters. This research provides a scientific foundation for the baijiu industry to strategically manage daqu storage and optimize ester aroma profiles.
Two wild strains of Torulaspora delbrueckii were isolated from the bark of a native White Oak (Quercus alba) tree near the North Carolina Arboretum in Asheville. Yeasts from the genus T. delbrueckii have been previously reported colonizing a wide variety of habitats; however, despite the relative abundance of this species, there is still no consensus on its fermentation behavior and suitability for the production of a palatable beer. Typically, T. delbrueckii strains are not capable of utilizing maltose efficiently and cannot complete fermentation to elevated levels of alcohol. However, in beer fermentation, T. delbrueckii can influence aromatic profiles in the brewing process, transforming hop aroma terpenoids and increasing the levels of ethyl hexanoate and ethyl octanoate. Two new wild strains, collected in western North Carolina and designated as C2B1 and HLB1, demonstrated outstanding fermentation performance on simple glucose media, achieving in excess of 5% ABV, but performed poorly in malt extract media, achieving only 1-2% ABV. Based on a preliminary evaluation, taste panel results indicate these wild strains could be used in the production of acceptable low-alcohol beers from an all-malt wort.
This article presents an approach based on deep learning (DL) algorithms, including artificial neural network (ANN) and convolutional neural network (CNN), in a simultaneous quantitative analysis of ethanol and methanol mixtures using Raman spectra. These models were optimized by a Bayesian algorithm in training and evaluation phases using 6,800 Raman spectra from both binary samples of ethanol/methanol-water and ternary mixture of ethanol, methanol, and water. Then, they were tested with 1,200 Raman spectra from commercial distilled alcoholic beverages spiked with methanol. The performance of ANN and CNN models was compared with principal component regression (PCR) and partial least squares regression (PLSR) based on three criteria: accuracy, precision, and limit of detection (LOD). The results show that both ANN and CNN models outperform PCR and PLSR regressions for quantifying ethanol and methanol concentrations in both binary and ternary samples. The results demonstrate that both ANN and CNN models outperform PCR and PLSR in the simultaneous quantification of ethanol and methanol across both binary and ternary mixture systems. In terms of accuracy, the mean absolute error (MAE) decreased at least twofold in methanol detection by both ANN and CNN models. Regarding precision, the standard deviation (STD) improved by a factor of two for both DL models. The ANN and CNN models achieved LODs of 0.9% (v/v) and 0.6% (v/v), respectively, both below the maximum tolerable concentration (MTC) of 2% (v/v) methanol allowed in distilled alcoholic beverages, whereas this performance could not be achieved using PCR or PLSR in this study.
