Barley has long been the primary grain used for malting and brewing, but projected declines in barley yield, growing demand for gluten-free products, and interest in novel fl avours are creating a market for alternative malts. Rice, a high-yielding, gluten-free crop with stable production forecasts, shows strong potential but remains underexplored at an industrial scale. This study evaluated the scale-up of malting for four rice varieties from laboratory batches (similar to 0.5 kg) to pilot-scale production (similar to 150 kg), with trials conducted across two malthouses and six breweries. Compared with barley, rice kernels exhibited distinct morphological and physiological characteristics, including a slenderer grain shape, lower germination energy, and reduced water uptake capacity. These traits created handling challenges during steeping and transport, requiring equipment modifi cations. Despite these hurdles, pilot-scale malting produced viable malt with extract yields of 38-64% and free amino nitrogen levels comparable to barley. Enzymatic activity profi les revealed lower alpha- and beta-amylase activity, but signifi cantly higher glucoamylase and limit dextrinase activity. Brewing trials demonstrated the potential of malted rice as an adjunct capable of contributing novel fl avour and colour attributes. However, adequate malt modifi cation or the use of exogenous enzymes was essential to prevent stuck mashes caused by starch gelatinization. Sensory evaluation highlighted cereal-like and nutty notes in non-pigmented malted rice, sake-like notes in aromatic varieties, and smoky characteristics in the pigmented variety, which also produced a purple-coloured wort. Overall, this work provides the fi rst industrial-scale assessment of malted rice, demonstrating its technical feasibility and its distinct enzymatic and sensory contributions to brewing. Although process adjustments are required, malted rice off ers a promising pathway to diversify brewing raw materials, expand gluten-free beer production, and reduce reliance on barley under a changing climate.
Kombucha fermentation is a complex process infl uenced by many diff erent process parameters and the dynamics of the microorganisms present. Since no universally established standards exist for large-scale production of kombucha, manufacturers still need to acquire the knowledge to establish controllable and reproducible processes. The aim of this study was to investigate the extent to which the kombucha fermentation process can be infl uenced by varying the oxygenation regime and the initial pH value. For this purpose, co-culture fermentations with the yeast Zygosaccharomyces bailii and the acetic acid bacterium Komagataeibacter hansenii were carried out under defi ned conditions, varying the type and intensity of aeration using various fixed aeration rates and controlled oxygen saturations. The pH values were varied in ranges between 4.1 and 7.5. The fermentations were comprehensively characterized via online and offl ine analytics, so that both the processes and the products could be chemically, microbiologically, and sensorially evaluated over time. By splitting the process into a suffi ciently long anaerobic phase of 4 days followed by an active aeration phase at 0.1 vvm for three to four days, a suffi cient oxygen supply was achieved under the given conditions to adequately convert the ethanol produced by the yeast into acetic acid by the bacteria. Sensory properties of the products were not negatively aff ected by oxidation reactions. Compared to reference processes conducted under traditional, static fermentation conditions, a process acceleration was achieved with equivalent sensory quality but significantly reduced alcohol concentrations (<0.08 %vol vs. 0.47 - 0.50 %vol. after 7 days). This study provides an example of how to produce a kombucha product under defi ned and accelerated conditions that includes an aerobic phase, and which can be used as basis for further production process developments.
Wort boiling is one of the most energyintensive steps in brewing and is traditionally operated at an evaporation rate of approximately 4 % to ensure suffi cient expulsion of DMS. This paper reports the first industrialscale evaluation of the retrofittable boiling system BubbleBoil, which generates bubbles via a controlled pressure drop at a ringshaped nozzle below the liquid surface, aiming to maintain wort quality at lower evaporation rates. The retrofitted boiling system delivered higher evaporation effi ciency than the reference system at similar evaporation rates, consistent with intensified stripping due to the increased gas-liquid interfacial area. Industrial operation achieved target evaporation rates as low as approximately 1.5-2.0 % while preserving wort quality, with no significant sensory differences compared to a brew produced with a conventional boiling system operating at a 4 % evaporation rate.
To determine the optimum temperature and the thermostability of enzymes in a standardized, accurate way is an elaborate, often time-consuming task. Knowledge of these characteristics of specifi c enzymes is of enormous importance for many applications, e.g. for optimizing the mashing regimes in breweries. In addition, due to ever-increasing gelatinization temperatures, cereal varieties (especially barley) are being sought and specifi cally bred whose starch-degrading enzymes exhibit increased optimal temperatures and temperature stabilities. A high-throughput method for the standardized determination of an enzyme's behavior to temperature was needed. Based on enzyme kinetic considerations, the half-life method was developed in which a small number of measuring points can provide a high density of information. This information encompasses the temperature optimum as well as the thermostability of enzymes that degrade high-molecular substrates, which applies to starch-degrading enzymes during mashing. Several cereal malts were analyzed for their betaamylase temperature optimum and thermostability. In doing so, several prerequisites were established for using the method to obtain valid and comparable results.
This study characterizes six new Czech flavor hop cultivars-Juno, Saturn, Pluto, Ceres, Eris, and Jupiter-using long-term datasets (2015-2025) that integrate chemistry, sensory profiling, and stress-resistance testing. Across cultivars, alpha acids were consistently moderate (4.6-7.2 % w/w), while total hop oils spanned 0.68-1.57 % w/w. These compact ranges, coupled with specific aroma profiles, support their suitability for dry hopping. Sensory results showed clear differentiation: Juno, Saturn, and Ceres expressed fruit-forward profiles; Pluto and Eris were citrus-driven; Jupiter exhibited a heavier woody-spicy character. Stress-tolerance assessments highlighted robust agronomic performance in several cultivars. Juno, Saturn, and Ceres combined favorable aroma with improved drought tolerance; among breeding lines tested in parallel, drought resistance frequently exceeded that of registered checks. Disease screening against downy mildew (Pseudoperonospora humuli) revealed high resistance in Saturn and very good resistance in Juno, Eris, and Ceres, whereas Pluto and Jupiter were less resistant. Overall, the new Czech flavor hops deliver modern aroma signatures with moderate alpha acids and practical advantages in drought and disease resilience. These traits have already driven adoption in Czech craft breweries and position the cultivars as versatile options for lager and top-fermented styles, particularly in dry-hopped applications.
Establishing vigorous and healthy plants is the first requisite for the future success of a new hopyard. Although hop micropropagation has been extensively studied, little information is available on subsequent ex vitro rooting and acclimatization phase. For example, materials and practices used to obtain an excellent hop plantlet ready for the field are often not referenced. The major challenge is to produce well-rooted plants without excessively boosting vegetative growth. New substrates (alternative to peat) and treatments (alternative to synthetic plant hormones) are likely required to address this issue and to increase the sustainability of the process. With this aim, we used micropropagated plantlets of cultivar Cascade and Nugget to assess the combined effect of rooting medium and biostimulant application on root and shoot development during two hardening periods: i) acclimatization in glasshouse, and ii) acclimatization in open air. Two growing media were tested: i) a standard peat-based substrate (control treatment), and ii) an experimental substrate, consisting of a mixture of the standard substrate and woodchip compost. Extracts of seaweed Codium fragile (Suringar) Hariot and Indian fig opuntia (Opuntia ficus-indica (L.) Mill.) were used as biostimulant agent. The experiments were set up in a completely randomized design with three replicates. Survival rate, shoot and root traits as well as rhizome development were determined. At the end of the study, the foliar biostimulant significantly increased root growth (21 % in length and 46 % in weight) and rhizome length (+ 46 %), while it had a moderate effect on shoot development. Hop cultivars tested in our study highlighted a very different way to allocate plant biomass during the hardening period, with Nugget having a root-to-shoot ratio twofold higher than Cascade. Finally, even though the experimental substrate did not affect plant traits during the first acclimatization period, it had a strong negative effect during the acclimatization in open air. Our findings provide practical guidance for nursery managers seeking to produce high-quality hop plantlets using sustainable materials and treatments.
The EU certification system distinguishes between seedless and seeded hops. The vast majority of hops produced within the EU belong to the category of hops without seeds, which allows a maximum seed content of 2 % (w/w). However, with increasingly restrictive herbicide regulations and the resulting growing difficulty of controlling male plants, compliance with this limit may become challenging in the future. Hop seeds are generally regarded as undesirable in brewing because of their high fat content, which promotes oxidative degradation and may impair beer foam stability. Previous studies on the influence of hop seeds on beer quality have produced contradictory results. In this work, the impact of hop seeds on beer quality was assessed through brewing trials. Lager beers were produced with additions of 50 and 70 g/hl hop seeds during wort boiling and after primary fermentation. The addition of hop seeds showed no measurable effects on foam stability or sensory properties. Even in long-term storage tests (6 months at 30 degrees C), no differences in quality were detected between beers brewed with and without seeds. The only noticeable change was a slightly increased alcohol content, likely resulting from amylolytic enzyme activity in the seeds. Seed proportions above the EU limit of 2 % therefore do not appear to negatively affect beer quality. Nevertheless, hop seeds do not contain relevant amounts of bitter compounds and thus offer no technological value in brewing. Instead, they merely contribute additional weight, increasing costs for harvest and subsequent processing steps such as pellet production. Moreover, seed formation raises the plant's nutrient demand during cultivation. Taken together, a high seed content is incompatible with economically and environmentally sustainable hop production.
In the new millennium, a lot of hop flavour cultivars with a unique "varietal aroma" have been bred and widely used for a dry hopping of beers. Seven flavour hop cultivars were also registered in the Czech Republic in recent years. Essential oils, depending on their concentrations, combinations and threshold levels, are responsible for diverse aroma and flavours of hop cultivars in dry cones and beers. In this study, we evaluated qualitative essential oils parameters and sensory aroma profiles in dry cones of 7 Czech and 23 world flavour hop cultivars by multivariate principal component analysis (PCA), which divides cultivars to quadrants. The Czech flavour cultivars Juno and Jupiter were placed in the first quadrant, influenced by higher geranyl acetate and methyl-4-8-decadienoate contents. The Kazbek, Ceres, Eris, Pluto and Saturn cultivars were grouped in the second quadrant, influenced by higher 2-MeBu-isobutyrate and geranyl isobutyrate contents, in essential oils analyses. However, in sensory aroma analyses, the Jupiter cultivar was placed in the first quadrant due to its woody aroma, whereas the Juno and Pluto cultivars were placed in the second quadrant due to their floral and grassy aromas. The Saturn cultivar was placed in the third quadrant due to a fruity aroma and the Kazbek, Ceres and Eris cultivars were grouped in the fourth quadrant due to their citrusy aroma. 7 Czech and 11 world flavour hop cultivars were also compared by sensory aroma analyses in dry hopping brewing tests. There was no correlation found between cultivar sensory aroma profiles in dry cones and beers, and differences and discrepancies in flavours for all of them. We proved that Czech hop flavour cultivars provided original sensory aroma profiles in beers and that they are useful for breweries in different beer styles.
Alcohol-free beer has become an asset even for small-scale breweries, since the consumption of low and non-alcoholic beverages is increasing steadily. Hence, the search for new, cost-effective and efficient methods of producing non-alcoholic beers that can also be realised by small breweries has also intensified. Maltose-negative yeast species play a key role in some of these low-threshold strategies to establish new and innovative alcohol-free beer products on the market. Due to this, the quest for new maltose-negative yeast species and strains becomes increasingly important. The ideal yeast species for this application shows an aroma profile with high consumers' acceptance and a low degree of attenuation, preferably accompanied by a fast fermentation rate. Since the large part of already known yeast species associated with trees, flowers and fruits are maltose-negative, fruit plantations seem the appropriate hunting grounds for viable candidates. Meadow orchards, which are extensively cultivated and traditionally tilled, promise a rich bounty of yeast species diversity. In addition, local breweries may also be able to utilise yeasts from their own region as a valuable fermentation and marketing asset to refine and to promote their own products. The meadow orchard investigated in this study harbors at least ten different microfungal species, of which three were tested in fermentation trials: Torulaspora delbrueckii, Candida peoriensis and Filobasidium wiringae. The species were inoculated and enriched in culture media, suspended in a standardized mixture (Pilsner Malt (10 % extract w/w), 20 IBU/L) and incubated for seven days at 25 degrees C and 60 % relative humidity. During the fermentation, the extract and pH-value were documented continuously. After this, afterwards the sugar utilisation of T. delbrueckii and C. peoriensis was analysed. The isolated strain of Torulaspora shows promising properties for producing alcohol-free beer, whereas C. peoriensis may be utilised in co-fermentations or in the production of fermented beverages other than beer.
Milk alternatives such as soy, almond, and oat drinks have become staples in supermarkets due to their health benefits, great taste and sustainability affects. An increasing number of breweries are entering oat drink production, as the manufacturing process closely resembles traditional brewing. This allows efficient repurposing of existing equipment such as mills, mash tuns, and storage tanks. For industrial-scale production, thermal preservation by direct heating is the preferred method to ensure microbiological stability while maintaining desirable sensory qualities and minimizing off-flavours. A key factor for cost-effective production is maximizing the operational time of the ultra-high temperature (UHT) process, minimizing interruptions for cleaning and sterilization. However, the formation of fouling layers in the high-temperature sections of the system-often within just a few hours-poses a significant limitation. The extent of fouling is strongly influenced by the upstream hydrolysis process. This study aimed to investigate the factors contributing to fouling to enable precise adjustments to equipment and process parameters, as well as to optimize cleaning procedures (CIP). Therefore, oat drink was produced in-house from oat flour via enzymatic hydrolysis and subsequently subjected to direct thermal treatment at both pilot and industrial scales. The results demonstrated a clear influence of the applied temperature profile on fouling behaviour. Sedimentation characteristics, colour development, and sensory attributes of the thermally treated oat drink were evaluated.
Beer has long been an important part of culture, with the brewing industry combining both traditional methods and modern innovation, which has helped beer's evolution over time. Today, the increasing prominence of microbreweries and their expanding market influence have led to a growing interest in identifying elements that can distinguish one beer from another. One such factor is the use of non-Saccharomyces yeast strains for fermentation. Among these, Zygosaccharomyces bailii (Z. bailii), typically known as a spoilage microorganism, presents promising potential as an unconventional yeast for brewing. This study aimed to evaluate the fermentation characteristics of Z. bailii and its potential to produce beers with desirable features. To assess its fermentative capacity, Z. bailii was tested both as a monoculture and in mixed fermentations with Saccharomyces cerevisiae (S.cerevisiae) at ratios of 1:1, 1:10, and 1:20, across two original gravities (16 degrees P and 12 degrees P) at 20 degrees C. After confirming that Z. bailii could successfully initiate and complete the fermentations, the final beer characteristics were analyzed. The results demonstrated that Z. bailii can produce an alcoholic beverage with unique attributes, including a significant decrease in the pH of the final beer. Furthermore, no issues arose during fermentation at high original gravities, and all fermentations achieved the desired ethanol levels. Notably, a strong phenolic character was detected in the final beers, though it was not considered particularly off-flavor. In conclusion, the use of Z. bailii offers the potential to create a complex and innovative beer profile that may appeal to consumers. While Z. bailii is not yet suitable for large-scale industrial applications, its distinct traits suggest that it could become a valuable yeast strain for future beer production.
Brewer's spent grain (BSG) has shown promise as a biosorbent to remove heavy metals from water. However, the adsorptive performance of native BSG is limited and modifications to enhance said performance suffer from extensive use of organic solvents. A potential solution is mechanochemical esterification, in which solid-phase reactivity is enhanced through high-energy milling. In this study, the adsorptive performance of BSG, which has been mechanochemically esterified with citric acid, was investigated (BSGE). The maximum adsorption capacities q(max) for nickel Ni(II), cadmium Cd(II), and lead Pb(II) ions were evaluated following bottle-point isotherm procedure in a buffered solution of sodium acetate, with a pH value of 4.5. The impact of the heavy metal initial concentration C-0 1 - 250 mg/L on the equilibrium capacity q(e) was studied and the data was fitted to the Langmuir and Freundlich models. The Langmuir model was best to describe data variance, as such q(max) was used to describe adsorptive performance: 65.83 mg/g for Pb(II), 24.72 mg/g for Cd(II), and 15.11 mg/g for Ni(II), with Langmuir constants K-L of 0.149 L/mg, 0.031 L/mg and 0.023 L/mg, respectively. These findings indicate that mechanochemical esterification yielded a 232.2 % Pb(II), 576.3 % Ni(II) and 164.4 % Cd(II) gain in adsorptive performance over native BSG. Based on molar comparisons, adsorptive affinities were determined as follows: BSGE (Pb > Ni approximate to Cd) and BSG (Pb > Cd > Ni).
Carrot juice is valued for its high vitamin and antioxidant content, necessitating gentle thermal processing to preserve these nutrients. Its slightly acidic pH value requires a two-step heating process, warranting optimization to enhance product quality and resource efficiency. This study investigated the impact of varying the first heating step between 100 and 130 degrees C on chemical, sensory, and microbiological parameters. While other chemical parameters remained stable, lactic acid content increased significantly from 55 to 1405 mg/L over downtimes, highlighting the influence of external factors that could not be influenced within the investigations. Lower heating temperatures compromised microbiological stability, with spore-forming bacteria (5 colony forming units per 20 mL) detected at just a 10 degrees C reduction. Sensory quality showed minimal change, with descriptive analysis identifying only 3 respectively 4 significantly different attributes out of 19 across the factors experimental parameter setting and technical repetition. The quality of raw materials had a more pronounced impact on sensory outcomes than the heating temperature. This study concludes that adjusting the first heating temperature has limited benefits for sensory quality but risks microbiological safety. Emphasis should therefore be placed on ensuring high-quality raw materials and consistent raw juice properties to maintain product quality.
Reducing primary energy consumption is a significant challenge in modern beer production. This study examines a patented boiling system that reduces this energy demand by significantly lowering the evaporation rate without negatively affecting relevant wort quality parameters compared to a state-of-the-art boiling system. The wort is heated in an external boiler and recirculated through nozzles at the bottom of the wort kettle. There, the change in pressure conditions results in the formation of bubbles. These bubbles rise, support uniform homogenization of the wort, and allow the expulsion of volatile components such as DMS-free. Trials in a 10 hL pilot plant show that primary energy consumption during wort boiling can be reduced by 23 % while maintaining MEBAK quality parameters such as TBI, DMS-free, coag. N, etc.. The results highlight the potential of this system to make a significant contribution to sustainable beer production and open up perspectives for the development of further energy concepts that were previously limited by a required minimum evaporation rate of approx. 4 %.
The Hot Steep Malt Sensory Evaluation, a method approved by the American Society of Brewing Chemists, was combined with the Check-All-That-Apply (CATA) method to assess the flavour profile of brewing malt. Ancient spring barley varieties (Hordeum vulgare L.), including Mahndorfer Hanna, Kraffts Riedgerste, and Alpine Pfauengerste, alongside a modern spring barley variety from the 2020 harvest, were malted with a standardised, small-scale malting process. Kilning was performed to produce Pilsner pale malt. The results of this study demonstrate that the Hot Steep Malt Sensory Evaluation, in conjunction with the CATA method, is an effective tool for differentiating the flavour characteristics of brewing base malt due to its simplicity and rapid execution. Both methods also proved to be suitable for detecting off-flavours in base malt. However, successful implementation requires the identification of relevant attributes and sensory training of panellists. Consequently, these methods are highly applicable for quality control within malt houses and breweries to assess malt quality. Both methods combined might improve quality control even in small-scale breweries.
Keptinis is a historical beer style from Lithuania which is brewed from a mash that is baked in parts or in total in a special oven. According to historical sources, one viable method to brew Keptinis is to mash-in with small amounts of brewing liquor at temperatures of approximately 65 degrees C and to bake the whole mash afterwards at ambient temperatures ranging from 280 to 300 degrees C in a so-called Duonkepis, a traditional bread oven. Maillard reactions, caramelisation products and eventually pyrolysis of the remaining starch can therefore be expected. The baked mash is then mashed in again in brewing liquor and lautered. The collected wort is not boiled but fermented subsequently with top-fermenting yeast strains. Available data on the brewing and fermentation characteristics of Keptinis is scarce. Hence, in a reproducible experimental design to reconstruct one method to brew this historical beer style, three brews and one control were conducted. For each experimental brew a grain bill of 6 kg Pilsener malt was mashed in at a grist-to-water ratio of 1:3 and mashed for 60 minutes at 65 degrees C. The mash of the three brews then was baked at 300 degrees C for 30, 60 and 120 minutes in a combination steamer using dry air. The mash of the control brew was not baked. The wort of all four brews was fermented with top-fermenting ale yeast at 20 degrees C. Prolonged baking time affected the pH of wort and beer, the degree of fermentation and the beer colour. The apparent degree of fermentation of the control was 91 %, whereas the prolonged baking time of the mash lowered it to 85 % (30 minutes), 84 % (60 minutes) and 82 % (120 minutes). EBC beer colour units were measured with 4 EBC in the control, 15 EBC units in the beer gained from the mash baked for 30 minutes, 35 EBC units (60 minutes) and 88 units (120 minutes) respectively. In addition, the thiobarbituric acid index (TBI) and the free amino nitrogen (FAN) of the final beers were determined.
This first investigation of beer foams using XPS enables a deeper insight than conventional analytics into the composition of beer foams as well as indications of criteria for good beer foam (NIBEM > 300 s; foam index, SKZ > 115). Due to the high sensitivity of this method, even the smallest amounts of residues can be detected in survey spectra. For an initial assessment, the total nitrogen content can be determined comparatively quick and easy, whereby a high value is obviously characteristic of good foams. The N 1s spectra can be employed to determine the quantity and size of proteins which are considered to be foam positive. A high O=C-N/C-NH2 ratio might indicate long peptide chains and seems to be foam positive, as the results reveal. Other groups can also be identified, such as polyphenols, whose influence on the foam is also assessed. Furthermore, the results indicate that appropriate reference measurements could provide a more precise determination of the proteins and influencing factors.
Hops stored at room temperature for an extended period are commonly referred to as 'aged hops'. Degradation of alpha and beta acids occurs during ageing, so the ageing process is accompanied by a significant increase in the concentration of branched-chain fatty acids (BCFAs): isobutyric acid (IBA), isovaleric acid (IVA), and 2-methylbutyric acid (2MBA). These three compounds, having rancid, cheesy, and/or sweaty flavours, are regarded as "off-flavours". It was previously reported that BCFAs contained at their threshold levels could enhance the flavour intensity of monoterpene alcohols (linalool, geraniol, and beta-citronellol; LGC) and change their aroma profiles. In this study, the behaviours of BCFAs during a 12-months ageing process were compared using five Japanese hop varieties. All BCFAs in the hops increased in all varieties during the total ageing period and a drastic increase was especially observed from 9 to 12 months. The content of linalool gradually decreased but plateaued at relatively high levels. In thiol-containing hops, 3-sulfanyl-4-methylpentan-1-ol (3S4MP) decreased drastically from 6 to 12 months, whereas 4-methyl-4-sulfanylpentan-2-one (4MSP) gradually decreased but was plateaued at relatively high levels. Next, to investigate the sensory effect of aged hops on aroma and taste profile of beer, model beers spiked with several combinations of monoterpene alcohols (LGC), 4MSP, and each BCFA were prepared. As a result, BCFAs commonly enhanced the characteristics of fruity, fullness, and maturity in the model beer spiking LGC. BCFAs also more enhanced the characteristics of tropical in coexistence with 4MSP. The sensory effect of BCFAs was expected to enhance hop-derived flavour of beer brewed with both geraniol-rich hops and 4MSP-rich hops. However, the sensory tests also showed an increase in rancid characteristics due to the presence of BCFAs. Therefore, test beers were brewed using fresh and aged 4MSP-rich hops. As a result, although the negative characteristics of rancid gradually increased depending on the dosage of aged hops, the positive characteristics of fruity, tropical, fullness, and maturity increased by mixing only 0.1 g/L of aged hops.
Certain volatile thiols are some of the most potent odour-active molecules found in food and beverages including beer. Even contents of a few mu g/kg in hops can be high enough to finally result in significant contributions to beer flavour, especially after dry hopping. Most published methods for the determination of free thiols in hops are based on gas chromatographic measurements. However, liquid chromatography in combination with tandem mass spectrometry (LC-MS/MS), as presented in this study, can also serve for their reliable quantification. This method was used to quantify 4-mercapto-4-methylpentan-2-one (4MMP), 3-mercaptohexan-1-ol (3MH), and 3-mercapto-4-methylpentan-1-ol (3M4MP) in 250 hop samples of 97 different varieties from 12 countries and 5 crop years (2019 - 2023). Thiol contents show high fluctuation ranges not only dependent on the variety but also on growing area, crop year or harvest date. Based on a large number of single results, it is suggested to create a general classification of varieties by assigning three main categories (low/medium/high) for their "thiol impact" in beer brewing.
This study focuses on the microfungal community found on hops, and because little data has been available until now, also seeks to increase the body of knowledge on these microfungal communities. Additional benefits may also be gained for brewers who use fresh hops in dry hopping and for beer styles that extensively rely on the technique of dry hopping by providing brewers with insights into which yeast species can enter the beer through hop cones, whether desired or undesired. In this context, the following considerations also come into play: Industrial production of beer requires reproducibility and consistent quality. Wild yeast species are usually undesirable and are considered contaminants. Conventional brewing uses only a few brewer's yeast strains that have been selectively bred over decades. Despite this, the so-called craft beer revolution has led to the spread of spontaneously fermented beers, for which the natural yeast diversity plays a crucial role. For brewers of such beers, the regional microbiome represents an invaluable resource. The biodiversity of the yeast microbiome that naturally occurs on brewing materials, such as hop cones, as well as its fermentation properties, can provide a competitive advantage. The identified yeast and microfungi species which were found in this study on wild hop plants were: Rhodotorula mucilaginosa, Papiliotrema flavescens, Moesziomyces aphidis, Debaryomyces hansenii, Hanseniaspora uvarum, Fusarium sporotrichioides, Meira spp., Wickerhamomyces spp. and Starmerella spp.
