Why was the work done: Hop creep remains a challenge for breweries producing dry hopped beers, as it leads to secondary fermentation that affects both beer quality and safety. Therefore, it is valuable to analyse hop creep across hop product types, growing regions, varieties, and concentrations to establish baseline metrics that reduce batch-to-batch uncertainty for brewers. How was the work done: This study investigated the role of hop product types, growing regions, varieties, and extent of hop creep in laboratory fermentations. Over 450 fermentations were performed, spanning five hop product formats (T90, Cryo, whole leaf, Noble, and enriched polyphenol aroma pellets/EPAP), six growing regions, and 19 hop varieties. Hops were added at 1 g or 2 g per 100 mL (1 or 2 kg/hL) of beer, reflecting industry usage. Samples were analysed in R with multi-way ANOVA and Tukey post-hoc analysis. What are the main findings: Significant (p < 0.05) differences were observed between hop varieties, origins, and product types, highlighting their role in hop creep. However, no significant difference was found with the amount of hops added. Widely used hop varieties, product types, and growing regions showed similar levels of hop creep. Why is the work important: While the phenomenon of hop creep requires further investigation, these results provide insight to anticipate hop creep by hop variety, product type, and origin. This will help improve the consistency, beer quality, and safety of dry-hopped styles.

Beer has over 600 flavor compounds and creates a positive tasting experience with acceptable sensory properties, which are essential for the best consumer experience. Spontaneous and mixed-culture fermentation beers, generally classified as sour beers, are gaining popularity compared to typical lager or ale styles, which have dominated in the USA for the last few decades. Unique and acceptable flavor compounds characterize sour beers, but some unfavorable aspects appear in conjunction. One such unfavorable flavor is called "mousy". This description is usually labeled as an unpleasant odor, identifying spoilage of fermented food and beverages. It is related as having the odor of mouse urine, cereal, corn tortilla chips, or freshly baked sour bread. The main compounds responsible for it are N-heterocyclic compounds: 2-acetyltetrahydropyridine, 2-acetyl-1-pyrroline, and 2-ethyltetrahydropyridine. The most common beverages associated with mousy off-flavor are identified in wines, sour beers, other grain-based beverages, and kombucha, which may contain heterofermentative lactic acid bacteria, acetic acid bacteria, and/or yeast/fungus cultures. In particular, the fungal species Brettanomyces bruxellensis are associated with mousy-off flavor occurrence in fermented beverages matrices. However, many factors for N-heterocycle formation are not well-understood. Currently, the research and development of mixed-cultured beer and non/low alcohol beverages (NABLAB) has increased to obtain the highest quality, sensory, functionality, and most notably safety standards, and also to meet consumers' demand for a balanced sourness in these beverages. This paper introduces mousy off-flavor expression in beers and beverages, which occurs in spontaneous or mixed-culture fermentations, with a focus on sour beers due to common inconsistency aspects in fermentation. We discuss and suggest possible pathways of mousy off-flavor development in the beer matrix, which also apply to other fermented beverages, including non/low alcohol drinks, e.g., kombucha and low/nonalcohol beers. Some precautions and modifications may prevent the occurrence of these off-flavor compounds in the beverage matrix: improving raw material quality, adjusting brewing processes, and using specific strains of yeast and bacteria that are less likely to produce the off-flavor. Conceivably, it is clear that spontaneous and mixed culture fermentation is gaining popularity in industrial, craft, and home brewing. The review discusses important elements to identify and understand metabolic pathways, following the prevention of spoilage targeted to off-flavor compounds development in beers and NABLABs.

BACKGROUND:Starch is the most abundant constituent (dry weight) in the barley endosperm, followed by protein. Variability of compositional and potentially related physical traits due to genotype and environment can have important implications for the malting and brewing industry. This was the first study to assess the effects of genotype, environment, and their interaction (G × E) on endosperm texture, protein content, and starch traits corresponding to granule size, gelatinization, content, and composition, using a multi-environment variety trial in California, USA. RESULTS:Overall, environment explained the largest variance for all traits (ranging from 23.2% to 76.5%), except the endosperm texture traits wherein the G × E term explained the largest variance (45.0-86.5%). Our unique method to quantify the proportion of fine and coarse milled barley particles using laser diffraction showed a binomial distribution of endosperm texture. The number of small starch granules varied significantly (P-value < 0.05) across genotypes and environments. We observed negative correlations between total protein content and each of enthalpy (-0.70), total starch content (-0.54), and difference between offset and onset gelatinization temperature (-0.52). Furthermore, amylose to amylopectin ratio was positively correlated to volume of small starch granules (0.36). CONCLUSION:Our findings indicate that environment played a larger role in influencing the majority of starch-related physical and compositional traits. In contrast, variance in endosperm texture was largely explained by G × E. Maltsters would benefit from accounting for environmental contributions in addition to solely genotype when making sourcing decisions, especially with regards to total protein, total starch, enthalpy, and difference between offset and onset gelatinization temperature. © 2024 Society of Chemical Industry.

There is growing interest in the potential of probiotics and other commensal dietary microbes to improve human health. This review will examine beer as a microbe-containing food and the considerations needed when using beer for probiotic and other live microbe delivery to the digestive tract. Although most beers harbor low numbers of live microbes after brewing is complete and the final product is an environmentally stressful environment which impairs long-term microbial survival, commercially-produced Lambic and sour beers can contain live microbes. Recent studies have also tested the viability and impacts of probiotic strains of Saccharomyces and lactobacilli strains in beer. The findings show there remains the need to adjust strain use and production practices to enable microbial growth and survival throughout the intended shelf-life. We discuss opportunities to increase microbial survival overall, as well as for strains that confer specific health benefits.

Proteomics can be used to assess individual protein abundances, which could reflect genotypic and environmental effects and potentially predict grain/malt quality. In this study, 79 barley grain samples (genotype-location-year combinations) from Californian multi-environment trials (2017-2022) were assessed using liquid chromatography-mass spectrometry. In total, 3104 proteins were identified across all of the samples. Location, genotype, and year explained 26.7, 17.1, and 14.3% of the variance in the relative abundance of individual proteins, respectively. Sixteen proteins with storage, DNA/RNA binding, or enzymatic functions were significantly higher/lower in abundance (compared to the overall mean) in the Yolo 3 and Imperial Valley locations, Butta 12 and LCS Odyssey genotypes, and the 2017-18 and 2021-22 years. Individual protein abundances were reasonably predictive (RMSECV = 1.25-2.04%) for total, alcohol-soluble, and malt protein content and malt fine extract. This study illustrates the role of the environment in the barley proteome and the utility of proteomics and machine learning to predict grain/malt quality.

Mousy off-flavor describes N-heterocycles compounds related to spoilage in the brewing industry. It has also been identified in sour beers through sensory analysis. Therefore, preventing spoilage N-heterocycles development is essential to preserve end-products and obviate economic losses. To this day, no methods or protocols have been reported to identifying mousy off-flavor compounds in a beer matrix. The main objective of this work was to develop a standardized quantification method for 2-acetyl-3,4,5,6-tetrahydropyridine (ATHP) in beer matrix, by Liquid Chromatography Mass Spectrometry with Electrospray Ionization (LC-MS-ESI). Extraction of ATHP in the samples was performed using QuEChERS (quick, easy, cheap, effective, rugged, and safe) technique. Over a dozen different potentially mousy cask-aged sour beers including other spontaneously fermented beverages were provided, based on sensory analysis, to determine the variation in ATHP levels. Results indicated ATHP was found in all the samples, ranging from 1.64 ± 0.06 to 57.96 ± 2.15 µg L-1. Herein, we described our detection method of mousy-off flavor compounds which enables future research to mitigate the occurrence of such defects in fermented beverages matrix.•ATHP content in samples varied from 1.64 ± 0.06 to 57.96 ± 2.15 µg L-1.•The recovery range of ATHP using LC-MS-ESI varied from 71% to 97%.•Basified QuEChERS salting-out procedure is applicable for ATHP extraction from beer and other fermented beverages matrices.

BACKGROUND:Hop creep continues to present an unresolved issue for the brewing industry, specifically stemming from those hops added to beer during fermentation. Hops have been found to contain four dextrin-degrading enzymes: alpha amylase, beta amylase, limit dextrinase, and an amyloglucosidase. One recent hypothesis predicts that these dextrin-degrading enzymes could originate from microbes rather than the hop plant itself.SCOPE AND APPROACH:This review begins by describing how hops are processed and used in the brewing industry. It will then discuss hop creep's origins with a new beer style, antimicrobial factors from hops and resistance mechanisms that bacteria use to counter them, and finally microbial communities that inhabit hops, focusing on whether they can produce the starch degrading enzymes which drive hop creep. After initial identification, microbes with possible links to hop creep were then run through several databases to search the genomes (if available) and for those specific enzymes.KEY FINDINGS AND CONCLUSIONS:Several bacteria and fungi contain alpha amylase as well as unspecified glycosyl hydrolases, but only one contains beta amylase. Finally, this paper closes with a short summary of how abundant these organisms typically are in other flowers.

Hops were traditionally used in brewing for the addition of isomerized alpha acids that balance the sugary wort with bitterness, though modern breweries are dry-hopping to add complex and unique aromas to their beers. An unintended consequence of high amounts of dry-hopping is the phenomenon known as hop creep, causing an increase in alcohol, carbonation, and diacetyl concentrations. The amount of diacetyl in a beer can be directly correlated to yeast health and vitality, controlled by the amount of free amino nitrogen (FAN) available to the yeast. In this study, both diacetyl and amino acid concentrations were measured prior to and 24 h after dry-hopping, at terminal gravity, and at the start of fermentation. These values were compared across twelve yeasts that are commonly used in dry-hopped beer or offer unique characteristics to fermentation. Experimental yeasts BY881, WLP518, K-97, and CK S102 all exhibited diacetyl concentrations below the aroma threshold for beer. The addition of dry-hops added a significant (p < 0.05) increase in FAN content to the fermenting beers, with most of the increases in serine, arginine, glutamate/glutamine, alanine, and glycine. These increases did not parallel the amino acid content measured in the grist or hops, where asparagine/aspartic acid, proline, and glutamate/glutamine were most prominent. Correlations between total FAN content and diacetyl concentration were calculated, as diacetyl is a precursor in the biosynthesis pathway of the amino acids valine and leucine. However, in this experiment, no correlation of amino acid and diacetyl concentration was observed between dry-hopped and traditional fermentations.

High wort beta-glucan may contribute to brewery processing problems such as poor run-off, slow filtration, and unwanted haze. To investigate how beta-glucanase impacts wort beta-glucan throughout mashing, 10 different mashes were considered with varied temperature profiles, malt bills, and levels of malt modification. The European Brewing Congress (EBC) and Institute of Brewing (IoB) mashes were employed to compare the effects of mash conditions on enzyme activity and beta-glucan content. Mashes were sampled periodically and evaluated for beta-glucan concentration and beta-glucanase activity using Megazyme kits adapted to the Gallery (TM) Plus BeerMaster Discrete Analyzer (Gallery). Enzyme activity quickly decayed in modified IoB mashes (average half-life 12.4 min) accompanied by logarithmic accumulation of wort beta-glucan. IoB beta-glucan percent extract ranged from 30.3% to 99.5%. In EBC mashes, a slow decay in enzyme activity was followed by an increased rate of decay after 30 min. The beta-glucan concentration in well-modified samples remained steady while enzyme activity was appreciable, though it increased after 40 min. As a result, beta-glucan percent extract remained relatively low, ranging from 11.9% to 34.3%. The beta-glucanase activity at lower temperatures compensates for high malt beta-glucan. Measuring wort beta-glucan in an EBC mash is insufficient in predicting malt performance in other mash styles. Methods for beta-glucan and beta-glucanase analysis adapted for the Gallery autoanalyzer increased throughput, enabling analysis of the enzyme and substrate throughout mashing.

The size and complexity of datasets resulting from comparative research experiments in the agricultural domain is constantly increasing. Often the number of variables measured in an experiment exceeds the number of experimental units composing the experiment. When there is a necessity to model the covariance relationships that exist between variables in these experiments, estimation difficulties can arise due to the resulting covariance structure being of reduced rank. A statistical method, based in a linear mixed model framework, is presented for the analysis of designed experiments where datasets are characterised by a greater number of variables than experimental units, and for which the modelling of complex covariance structures between variables is desired. Aided by a clustering algorithm, the method enables the estimation of covariance through the introduction of covariance clusters as random effects into the modelling framework, providing an extension of the traditional variance components model for building covariance structures. The method was applied to a multi-phase mass spectrometry-based proteomics experiment, with the aim of exploring changes in the proteome of barley grain over time during the malting process. The modelling approach provides a new linear mixed model-based method for the estimation of covariance structures between variables measured from designed experiments, when there are a small number of experimental units, or observations, informing covariance parameter estimates.

A novel data fusion method based on the use of visible/near-infrared (VNIR) and shortwave infrared (SWIR) imaging sensors, to distinguish between pregerminated and ungerminated barley grain is proposed. Spectral imaging was used to fingerprint germinated and ungerminated barley grain from a total of 5640 average spectra representing single barley kernels varying with respect to germination time. Chemometric approaches utilising partial least squares-discriminant analysis (PLS-DA) and multiblock sequential and orthogonalized partial least squares-linear discriminant analysis (SO-PLS-LDA) and sequential and orthogonalized covariance selection-linear discriminant analysis (SO-CovSel-LDA) were used to build classification models. SO-PLS-LDA achieved a total classification rate of 99.88%, while SO-CovSel-LDA resulted in a classification accuracy of 97.46% when a maximum of 8 variables were selected from each data block (VNIR and SWIR) - models were validated on an independent test set. The use of multiblock approaches led to increased prediction accuracy, compared to PLS-DA, and a viable solution to address the industry problem to detect pregerminated malting barley in a rapid, non-destructive manner. This represents a significant advance with respect to the current dated methods which are hindered by time-consuming wet chemistry techniques and human subjective bias. The potential of the proposed new technique also has the further advantage of moving toward multispectral systems which can be used to detect pre-harvest germinated barley using an even more computationally rapid and affordable online sorting machine incorporating the wavebands of importance selected by SO-CovSel-LDA. The study highlights how sequential and orthogonalised data fusion approaches, in the food and agricultural sector, are powerful solutions to real world problems.

Brewing is possibly the oldest fermentation process. Around 12,000 years ago, people fermented a mix of grains and other plants to produce a sweet liquid that they found made them happy and relaxed, and helped build communities. The controlled process of germination and drying grain (malting) followed a short time later, allowing these early brewers to have more control over the process. Over the subsequent millennia, the malting and brewing processes have become more precise with the use of predominantly barley as a source of color, fermentable sugars, and flavor; hops for bitterness and aroma and yeast to produce alcohol, CO2, and some additional flavors. Also, over the many centuries, different beer styles have evolved based on different grains or plants, alternative processing, and diverse yeasts. Today, the global brewing industry is worth over $500B and contributes to 1 in every 110 jobs. Maltsters and brewers have in-depth knowledge of the hundreds of biochemical reactions that occur in malting, brewing, and fermentation. This chapter will cover the historical foundations of malting and brewing and discuss key factors that influence processing, flavor, aroma, and other aspects of quality.

Malting barley productivity and grain quality are of critical importance to the malting and brewing industry. In this study, we analyzed two experiments: a multi-environment variety trial and a nitrogen management trial. In the first experiment, we analyzed 12 malting barley genotypes across eight locations in California and three years (2017-18, 2018-19 and 2020-21). The effects of genotype (G), location (L), year (Y) and their interactions were assessed on grain yield (kg ha-1), grain protein content (GPC; %), individual-grain weight, grain size (plump and thin; %), onset gelatinization temperature (GT), peak GT, offset GT, difference between onset and peak GT and difference between peak and offset GT. L, Y and their interaction explained the largest variance for all traits except peak GT and difference between onset and peak GT, for which G explained the largest variance. The 2020-21 samples formed partially distinct clusters in principal component analysis, mainly discriminated by high percentage of thin grains and high onset GT. In the second experiment, we analyzed a dataset with two genotypes across three locations (with varying nitrogen fertilizer levels) from the 2016-17 season to assess the effect of added nitrogen on the same traits. Added nitrogen at tillering explained 18% of variance in the difference between onset and peak GT, and 5% of the variance in GPC, but was minimal for all other traits, with the largest variance explained by location and genotype. These findings illustrate the key roles of G, L and Y in determining malting barley productivity and quality.

Sorghum (Sorghum bicolor), a grass native to Africa, is a popular alternative to barley for brewing beer. The importance of sorghum to beer brewing is increasing because it is a naturally gluten-free cereal, and climate change is expected to cause a reduction in the production of barley over the coming decades. However, there are challenges associated with the use of sorghum instead of barley in beer brewing. Here, we used proteomics and metabolomics to gain insights into the sorghum brewing process to advise processes for efficient beer production from sorghum. We found that during malting, sorghum synthesizes the amylases and proteases necessary for brewing. Proteomics revealed that mashing with sorghum malt required higher temperatures than barley malt for efficient protein solubilization. Both α- and β-amylase were considerably less abundant in sorghum wort than in barley wort, correlating with lower maltose concentrations in sorghum wort. However, metabolomics revealed higher glucose concentrations in sorghum wort than in barley wort, consistent with the presence of an abundant α-glucosidase detected by proteomics in sorghum malt. Our results indicate that sorghum can be a viable grain for industrial fermented beverage production, but that its use requires careful process optimization for efficient production of fermentable wort and high-quality beer.

Although proline is the most or second most abundant amino acid in wort and grape must, it is not fully consumed by the yeast Saccharomyces cerevisiae during alcoholic fermentation, unlike other amino acids. Our previous studies showed that arginine, the third most abundant amino acid in wort, inhibits the utilization of proline in most strains of S. cerevisiae. Furthermore, we found that some non-Saccharomyces yeasts utilized proline in a specific artificial medium with arginine and proline as the only nitrogen source, but these yeasts were not suitable for beer fermentation due to their low alcohol productivity. For yeasts to be useful for brewing, they need to utilize proline and produce alcohol during fermentation. In this study, 11 S. cerevisiae strains and 10 non-Saccharomyces yeast strains in the Phaff Yeast Culture Collection were identified that utilize proline effectively. Notably, two of these S. cerevisiae strains, UCDFST 40-144 and 68-44, utilize proline and produce sufficient alcohol in the beer fermentation model used. These strains have the potential to create distinctive beer products that are specifically alcoholic but with a reduction in proline in the finished beer.

Cereal grains have been domesticated largely from food grains to feed and malting grains. Barley (Hordeum vulgare L.) remains unparalleled in its success as a primary brewing grain. However, there is renewed interest in “alternative” grains for brewing (and distilling) due to attention being placed on flavor, quality, and health (i.e., gluten issues) aspects that they may offer. This review covers basic and general information on “alternative grains” for malting and brewing, as well as an in-depth look at several major biochemical aspects of these grains including starch, protein, polyphenols, and lipids. These traits are described in terms of their effects on processing and flavor, as well as the prospects for improvement through breeding. These aspects have been studied extensively in barley, but little is known about the functional properties in other crops for malting and brewing. In addition, the complex nature of malting and brewing produces a large number of brewing targets but requires extensive processing, laboratory analysis, and accompanying sensory analysis. However, if a better understanding of the potential of alternative crops that can be used in malting and brewing is needed, then significantly more research is required.

Proline contributes to the taste and flavor of foods. The yeast Saccharomyces cerevisiae poorly assimilates proline during fermentation processes, resulting in the accumulation of proline in fermentative products. We performed here a screening of in total 1138 yeasts to obtain strains that better utilize proline. Our results suggest that proline utilization occurs in the genera of Zygoascus, Galactomyces, and Magnusiomyces.

Assessing the health and wellbeing of animals in their natural habitats is a critical yet difficult aspect of species management and conservation. Non- and minimally invasive techniques are increasingly being sought by people working with animals so they can easily monitor the health and wellbeing of the animals without causing them distress. One noninvasive technique that has been in this space is infrared (IR) spectroscopy, which measures the interaction of IR radiation with matter. The ability of IR spectroscopy, especially near-infrared (NIR) and mid infrared (MIR) spectroscopy, to evaluate and monitor animal nutrition, as well as to discriminate physiological attributes of animals (e.g., stress, reproductive status), has been demonstrated by several studies with livestock and wildlife species. However, the use of IR spectroscopy techniques is laden with several challenges, including sample preparation and stability, reliability, and transferability of prediction models. This paper reviews research on the analysis of fecal samples using IR spectroscopy as a proxy in animal health and wellbeing studies. The main challenges of using IR spectroscopy as a portable technology for in-field analysis are also discussed while highlighting key aspects to be considered for in-field applications of NIR and MIR spectroscopy in animal health and wellbeing studies.

Malted barley (Hordeum vulgare) is a crucial component of beer, and it has been established that barley genotype has an effect on malting quality and beer flavor. This study extends this exploration by evaluating the effects of genotype, environment, and management on malting quality. Five fall-planted malting barley lines were grown in three locations, each representing a distinct growing environment in the Pacific Northwest (United States), and under nitrogen (N) treatments: control (N1) and N application at heading in addition to the control (N2). Genotype x location interactions were observed for all agronomic (yield, test weight) and grain quality metrics (grain protein, plumpness), and N treatment x genotype interactions were observed for grain protein and plumpness. Overall, N2 increased grain protein, without exceeding specifications, by almost 1% point. Based on random forest analysis, the major driver of all-malt index score was grain protein, followed by peak gelatinization temperature, germination energy, and water sensitivity. Still, over 70% of variation in all-malt index score was unexplained, which is likely due to genotype and location differences, as indicated by principal component analysis. This research confirms the agronomic potential of fall-planted malting barley in the Pacific Northwest and, although micromalted samples did not meet industry specifications, trends were identified that indicate the potential for these varieties at these locations. This research also demonstrates the potential of N management to fine-tune malting quality through grain protein, and that malting quality is influenced by genotype and environment, though many of the specific drivers remain unknown.

As the environmental impacts of beer are of increasing concern to maltsters, brewers, and consumers, perennial cereal crops can offer a more sustainable solution. One new cereal species of interest to the brewing industry is intermediate wheatgrass (Thinopyrum intermedium subsp. intermedium), developed by The Land Institute, in Salina, Kansas, U.S.A., under the branded name Kernza (R). It has been touted as a more sustainable alternative to barley and wheat in its requirements for less water and nutrient additions and reduced tilling of agricultural fields. To date, no published research has been performed to assess the potential for this grain for the malt and beer industries as a barley replacement. Here, the "M5" variety Kernza grain was micromalted and the finished malt was compared with both the raw grain and to a reference raw and malted barley (Hordeum vulgare L. var. Copeland). All samples were analyzed for starch gelatinization temperatures via differential scanning calorimetry, amino acid composition, alpha-amylase, diastatic power (DP), total and soluble nitrogen and protein, Kolbach Index (KI), extract, wort free alpha-amino nitrogen (FAN), wort beta-glucan, wort color, pH, and clarity. The Kernza malt produced sufficient extract and FAN for typical fermentations with low beta-glucan content. However, extract and FAN in the Kernza malts were lower than in the barley reference, and the Kernza worts exhibited higher levels of undesirable soluble protein and haze. Interestingly, the DP for both the raw and malted Kernza were similarly high, indicating that both of the raw grains exhibit high enzymatic activity, which malting did not increase substantially. Results support that Kernza could be an acceptable candidate for malting and subsequent wort production; however, specific techniques may be required to utilize this malt most effectively. Supplemental data for this article is available online at https://doi.org/10.1080/03610470.2022.2026662 .