The Brewers Forum 2022

Session Chair:
Sandra Stelma (Process capacity, Agility and Futures Manager- Beer and Spirits, Diageo, IE)

Production of low alcohol beer – a review of methods
By Alejo Giron Gonzalez, Grupo Mahou-San Miguel
Beer sales in Spain reveal a unique characteristic of the Spanish market. In 2020, non-alcoholic beer represented 13% of beer consumed in Spain. Recent NABLAB product releases signal the interest of consumers in this product category. Low alcohol and non-alcoholic beer has become a worldwide trend in recent years and it is forecasted to increase up to 20% of sales volume in certain markets. Consumers demand healthier options and are increasingly looking for better tasting alternatives to regular beer.  As the market leader in Spain, Mahou S.A. has produced non-alcoholic beer for over 25 years and has developed an insight knowledge of NABLAB production and development.  This presentation will review several approaches to brewing non-alcoholic beers including traditional cold fermentation, the use of novel alternative microorganisms and physical removal of alcohol.  It will cover the challenges and advantages of each method and strategies to optimize the production and flavor profile of NABLAB products.

Oxidation risk emerges as the main weakness of NABLABs beers, much more than the absence of wort aldehyde reduction
By Margaux Simon and Sonia Collin, UC Louvain
A growing interest for non-alcoholic (NAB, ≤ 0.5% ABV) and low-alcoholic beers (LAB, 0.5-1.2 % ABV) emerged in the last decade. Two main types of processes are currently used to produce NABLABs: physical (dealcoholization or membrane systems) and biological methods (cold contact or use of « maltose-maltotriose negative » yeasts). The aim of the present work was to assess the quality of eleven commercial NABLABs available on the Belgian market, issued from different technological processes. Surprisingly, most of them already exhibited when fresh the usual staling defects of a six-months lager beer (dimethyltrisulfide, bêta-damascenone, methional, sotolon, oxidized flavan-3-ols,…). In absence of ethanol, strong degradations were also noticed for isohumulones and flavan-3-ols, leading to unpleasant bitterness, more color and colloidal instability through storage. In conclusion, as oxidation risk emerges as the main weakness of NABLABs beers, efficient antioxidants are needed to improve their acceptability.

A new approach to produce a non-alcoholic beer (≤0,0% abv) by a dual stage process: limited fermentation and vacuum evaporation.
By Paulo Magalhães, Superbock Group
Despite the increasing demand, the production of non-alcoholic beers is still limited by unsatisfactory or artificial flavour and taste. In this study, a new approach to producing non-alcoholic beer (≤0,0% abv) is presented, in which the main alcohol-reducing techniques, limited fermentation and vacuum evaporation by the Spinning Cone Column (SCC) technology were combined. The process was optimized by the variation of the main technological parameters to determine the effect of different operating conditions on the quality and organoleptic properties of the dealcoholized beer.Some important beer quality parameters were determined, as well as the volatile composition by gas chromatography and the organoleptic characteristics by a trained panel and consumers. The findings indicated that the dual stage method in an appropriate process to produce 0,0% abv beer. The content of aldehydes and other esters compounds were lower in the beer produced by dual stage process. On the other hand, the report of the panel showed that there was preference by the 0,0% abv prototype since it denoted a more standard beer profile and with fewer off flavours, such as mercaptans and sulfur compounds.

How low can you go? – development of a biological strategy for 0.0% ABV beer production
By Brian Gibson et al., TU Berlin
Fermentation with maltose-negative yeasts is a viable option for low-alcohol beer brewing. Production of beers with 0.0% ABV is however still carried out via ‘physical’ methods of alcohol removal. Reduced production and capital expenditure costs would be expected if such beer could be made in a ‘biological’ process with speciality yeast. Here, four yeast species – originally from sourdough cultures and known to be suitable for low alcohol (0.5% ABV) brewing – were assessed for their ability to produce beer via cold-contact fermentation. The ability to reduce wort aldehydes while producing minimal alcohol was assessed. Torulaspora delbrueckii showed the most potential, largely due to its sensitivity to cold. A selected strain had the ability to reduce aldehydes below flavour thresholds, while producing as little as 0.03% alcohol – much lower than the 0.28% ABV produced by S. pastorianus under the same conditions. Beers produced with T. delbrueckii and the reference strain could not be distinguished in sensory trials, despite the differences in alcohol. Results suggest that T. delbrueckii could be used in cold-contact fermentation to produce beers with alcohol at, or close to, 0.0%.

Session Chair:
Walter König (Director Bayerischer Brauerbund and Secretary, German Malting Barley Association e.V., DE)

Is there a “Terroir” impact of local brewing barleys on beers?
By Anne Pietercelie et al., Institut Meurice
Since 2016, the Belgian beer culture has been included in the UNESCO list of intangible heritage of humanity. However, it is clear that some of the raw materials that make up our beers, such as barley malt and hops, are rarely of Belgian origin. This research project presented here is part of a dynamic of local valorisation of malting barley by studying the influence of the barley variety and its growing conditions (geographical location, cultivation practices, etc.) on the flavour of the beer. Two approaches are envisaged: the first consists of choosing the same variety, sown in different cultivation areas in Wallonia (pedoclimatic effect), while the second aims to monitor several varieties on the same plot (varietal effect). In both cases, the barleys are harvested, stored, and malted under the same standardised conditions and are then used in an identical beer recipe that will be characterised analytically and sensorially in order to highlight a “terroir” impact on the finished product. The results of the 2021 harvest are discussed and the first trends identified.

Pythium oligandrum as a biocontrol agent against Fusarium in the malting of brewing cereals
By Carlo Antonio Ng et al., University of Chemistry and Technology Prague
The growing incidences of Fusarium head blight in wheat and barley due to changing climate conditions leading to growing food safety concerns caused by the increased production of mycotoxins. Due to this, various control methods have been proposed including chemical and physical treatments to suppress fungal growth in malting, with biological methods showing promise due to the absence of undesirable by-products. The potential of Pythium oligandrum as a novel biocontrol agent in suppressing Fusarium culmorum growth during the malting of wheat and barley was investigated through RT-PCR. The effect of fungal suppression on the production of deoxynivalenol (DON) and deoxynivalenon-3-glucoside (D3G) was determined through LC-MS/MS. Addition of P. oligandrum showed promise when added with the steeping water in the earlier stages of the malting process. Varying the treatment dosages of the biocontrol agent yielded negligible differences.  The decreases in fungal DNA resulted to decreases in the produced mycotoxins, resulting total DON reduction of up to 86% in wheat malt, and up to 37% decrease in barley malt with the application of P. oligandrum, compared to the untreated grains.

Identification of factors linked to beer gushing in order to develop a rapid test for gushing potential detection in raw material
By Julien Billard, IFBM-Qualtech

Beer gushing is an unprovoked over-foaming following the opening of a bottle. Primary gushing is highly dependent on barley growing and harvesting climatic conditions. This phenomena can have economical and reputational consequences for breweries. Current techniques, such as the modified Carlsberg test, provide information on a predictive gushing potential of malt with a high uncertainty and is time consuming. Thus, a rapid screening test on raw material to detect the gushing potential of malt could be of interest for the malting & brewing industries. The aim of this study is to identify markers of beer gushing in order to develop a method for their detection and/or quantification.
Proteins from industrial malt batches were extracted and analyzed. A bioinformatic strategy has been used to identify proteins of interest linked with gushing potential. Afterwards, recombinant target proteins were used to produce antibodies in order to develop an ELISA test against these markers on raw materials. The detailed methodology and the results will be presented and discussed.

Session Chair:
David De Schutter (Innovation & Technology Development Director Europe, AB Inbev, BE)

The use of wood alternatives for beer flavouring
By Gert De Rouck et al., KU Leuven
Wood barrel ageing of beer is very popular nowadays. However, need for space – unpredictable outcome – lots of manual work,.. are important drawbacks for up-scaled production. Chips, cubes, staves, powder, wood extracts as alternatives are available. The impact on the wood flavour is to expect although to what extent? No knowledge is present on the physico-chemical and the microbial quality of the final beer.In this study, 260 beers, brewed in our pilot brewery, varies in wood product (from chips to extract), origin (French/American), concentration, contact time, re-use, batch-to-batch difference, original extract, and yeast. Wood flavour is determined via HS-SPME-CGC-MS  and sensory profiling. The impact on colloidal stability and foam stability is measured and microbiology control was performed.French oak is more spicy/pungent compared to American Oak (malate-sweet), contact time varies from 2-3 weeks when 3g/l is used (but product depending). French oak has a positive impact on colloidal stability, but all wood is negative for foam stability. Different batches resulted in equal beers. Higher alcohol results in increased flavour extraction. More conclusions will be presented.

Lager barrel aging. Evolution of key physical-chemical parameters
By Igor Oyarbide Sangroniz and Alejo Giron Gonzalez, Grupo Mahou-San Miguel
Barrel aging of beer has become a worldwide trend in the last couple of decades among craft brewers. Apart from existing traditional Old World beer wood aging, new styles have adopted the use of oak barrels in the production process, normally using ex-spirits barrels for stronger versions of ale styles.  Yet, barrel aging of lagers still remains uncommon.  This study focuses on investigating how barrel aging affects common parameters of lager beer.  Original extract, ADF alcohol, color, pH, bitterness and VDK among others were monitored during the barrel aging process. Microbiological analyses were performed as well to determine the presence of possible yeast and bacteria contaminants. The results and techniques employed will be discussed to help brewers understand the challenges of barrel aging and how beer evolves during its maturation process.

Flavor evaluation of beer with the addition of oak during the brewing process
By Mayu Ohata et al., Sapporo Breweries Ltd.
Oak barrel is commonly used for aging and flavoring wine and whiskey. Some craft brewers have attempted to produce barrel-aged beer. Oak wood imparts a specific flavor to the finished beer, such as vanilla, smoky, spicy, and roasty. However, barrel-aging method has several disadvantages because of the need for barrels and the time-consuming process and so on. In this study, we investigated the process of beer making by adding oak during the brewing process. Oak addition is performed at the time of mashing, primary fermentation, secondary fermentation, and maturation. In previous studies, the oak material was sometimes added after fermentation but not before fermentation. We evaluated the finished beer by analyzing the oak-derived compounds and by sensory evaluation. The results revealed that aroma of oak was imparted to the beer, regardless of the oak addition timing and within a shorter time than that in the case of barrel aging. Some differences in flavor characteristics were confirmed between the finished beers. These results suggested that the addition of oak during the brewing process is effective in imparting the characteristic flavor and aroma to the finished beer.

Session Chair:
Aleksander Poreda (Head of Kraków School of Brewing, PL)

Binding of staling aldehydes to the beer matrix
By Carolina Maia et al., Nottingham University
Aldehyde adducts in beer include those with SO2, amino and sulfhydryl groups. Bound aldehydes are not reduced by yeast and are carried forward with the potential to be released and cause flavour change through shelf-life. Whilst this is known to be a major route to beer staling, surprisingly little is understood about the interactions between aldehydes and the beer matrix which give rise to the specific impacts of ageing on beer flavour. Here, we isolated and concentrated the beer matrix from 3 commercial lager beers by freeze drying and re-constitution. Free aldehyde concentrations were measured by HS-SPME-GC-MS in fresh beer and re-constituted matrix. Sulfite was completely lost during freeze drying, enabling independent adjustment for study of competitive binding between sulfite and other matrix components. A series of ‘challenge’ experiments were then conducted where the impacts of individual aldehyde additions on the displacement of other staling compounds were studied. Results provide new insights into the binding and displacement of aldehydes in beers as determined by the binding affinities of the individual compounds and the individual characteristics of a beer’s matrix.

Consistent detection of strict anaerobic beer spoilers including Megasphaera cerevisiae using an automate anaerobic jar system.
By Wade Begrow, Founders Brewing
Beer quality can be dramatically affected by strictly anaerobic bacteria including Megasphaera spp. In contrast to lactic acid bacteria (e.g. Lactobacillus brevis), Megasphaera can produce detrimental metabolites in beer such as hydrogen sulfide and organic acids including butyric acid and isovaleric acid. The risk of spoilage from strict anaerobes has intensified in recent decades because of advancements in low-oxygen packaging technology. Ultra-low total package oxygen values (<300 ppb) are desired to preserve beer freshness and shelf stability, but low TPO also opens the door for strict anaerobes to survive and potentially spoil beer after it has left the brewery.Traditional microbiological methods for bacterial beer spoilers may not be able to recover strict anaerobes including Megasphaera cerevisiae because of their inability to rapidly create and preserve anaerobic conditions during incubation. The inability to detect strict anaerobes can provide a false sense of security and could lead to serious product issues.The Anoxomat® III Anaerobic Culture System by Advanced Instruments is used extensively in clinical microbiology testing programs for detecting strict anaerobes.

Boosting intense natural fruity esters in beer with fermentation
By Luk Daenen et al., AB-Inbev
To explore the potential of non-Saccharomyces yeasts, a screening was performed based on flavour profile and fermentation performance by fermenting beer wort under anaerobic and aerobic conditions. Pichia kluyveri was found to produce exceptionally high quantities of esters such as isoamyl acetate, which is the main compound responsible for the pleasant banana aroma often found in beer. A further selection of P. kluyveri strains was made based on the ratio of isoamyl acetate over ethyl acetate which can impart a solvent character in high concentrations. By optimizing the conditions of brewing and fermentation, an intensely fruity beer can be produced which contains over 150 ppm isoamyl acetate which is about one hundred times the concentration typically found beer. This very fruity beer can be applied to enhance and diversify the natural fruitiness of lager beers, specialty beers, non-alcoholic beers, as well as other innovative beverages.

Entry and reduction of microplastics and microparticles in beer production lines
By Jörg Zacharias and Veronika Knöchel, Krones
Intensive debates are currently going on about the occurrence and effect of microplastics and microparticles in the environment. This also concerns producers of beverages. But research is still in its infancy and often reliable scientific data are lacking. Many studies focus on water as it allows for a simple analysis due to its homogeneous and transparent appearance compared to un-/filtered beer. But to this day no universal or standardized analytical method was established to define microplastics and microparticles quantities or limits. As a result, the focus is on the measurement of microparticles, and not in particular on microplastics. So, tests to find out where and to which extend microparticles are generated, entered and removed in beer filling plants were carried out using particle counters and fluorescence microscopy. These tests are done for various filling lines. Beverages, bottles, caps and the beer itself are measured at different stages. Bottle washer and filter systems are also considered. This leads to filling concepts with the lowest possible particle entry. First approaches of particle avoidance and removement have already been implemented and will be discussed.

Session Chair:
Goran Matic (Western Europe Supply Chain Excellence and Innovation Director, Molson Coors, UK)

Formation of Desired Key Odorants in Wheat Beer – a Comparison with the Undesired Toxicologically Relevant Styrene
By Michael Granvogl and Valerian Kalb, Universität Hohenheim
The use of wheat and barley malts for wheat beer production introduces the so-called phenolic acids. During fermentation, these acids are transferred into the corresponding vinyl aromatics by top-fermenting yeasts. For ferulic and p-coumaric acid, decarboxylation results in the formation of the two key odorants 2-methoxy-4-vinylphenol and 4-vinylphenol, responsible for the typical, well-known clove-like and slightly phenolic wheat beer aroma. Unfortunately, this formation is accompanied by the release of the undesired and toxicologically relevant styrene (classified as possibly carcinogenic to humans (class 2B) by the “International Agency for Research on Cancer”) from cinnamic acid. Therefore, the desired and undesired volatile vinyl aromatics and the corresponding phenolic acid profiles of a large number of commercially available wheat beers were analyzed via stable isotope dilution analysis (SIDA) by means of HS-SPME GCxGC-ToF-MS and LC-MS/MS, respectively. Pale, unfiltered, alcohol reduced, light, and two dark wheat beers were analyzed to get knowledge on the impact of dealcoholization process, type of yeast, and roasting degree on the vinyl aromatic and phenolic acid pattern.

New kombucha with standardized microbial consortia
By Laurence Van Nedervelde et al., Institut Meurice
Kombucha is a traditional low-alcoholic beverage made from sweet tea and transformed by a microbial consortium (SCOBY) consisting of yeasts and acid bacteria. Considered as a niche beverage for decades, kombucha is now invading grocery stores, supermarkets, and cafés as an alternative to sodas. Its success is attributable to its low sugar content, its all-natural composition and the many health claims relayed by the scientific literature. This study aims to develop a standardized microbial consortium efficient for the production of kombucha. For this, we isolated and screened for the most suitable yeast and bacterial strains. In addition to the nature of the microorganisms constituting the SCOBY, different parameters influencing the taste and final characteristics of kombucha are investigated: the initial sugar concentration, the tea type, the proportion of each microbial partner within the SCOBY, the fermentation temperature, and the fermentation time. The results highlight the main impact of bacterial species on the organic acids profile and the secondary impact of yeast metabolism on the chemical composition of kombucha, via invertase and fermentative activities.

Bottle refermentation determines the quality of gueuze beers
By Dries Bongaerts et al., Vrije Universiteit Brussel
Lambic beer can be enjoyed as such but is usually a basis for other beers. An example is gueuze, a blend of young and old lambic beers, which is refermented in the bottle. To better understand the influence of storage time on the quality of gueuze, which is of interest for both consumers and producers, bottle refermentation was followed as a function of time. This was approached through novel microbiota and metabolite analysis techniques. Culture-dependent and -independent identification mapped the microbial species diversity and community dynamics. Metabolomics unravelled substrate consumption and metabolite production. The early bottle refermentation microbiota reflected that of the maturation phase of lambic beer production. However, the species diversity decreased over time and, after three months, mainly Brettanomyces occurred. The metabolites were mostly linked with this yeast metabolism, including an increase in several alcohols, ethyl acetate, and ethyl lactate. Other compounds linked with the typical Brett flavour slightly decreased during the first months of bottle refermentation but increased again after six months. These data can be used to optimize the storage time.

Ageing beer using the Solera Method
By Luis Miguel Barrera Arbelaez, Grupo Mahou-San Miguel
Application of the solera method to beer production. A solera is essentially a series of barrels containing an identical liquid of consecutive ages. In the case of sherry wine, the method consists of extracting a quantity of wine at intervals (25 to 50%) throughout the year, and then the barrel is refreshed with wine of the same style but a little younger. This is done because the younger wine will gradually take on the character of the older wine, and after several years, the wine in the barrel becomes practically indistinguishable from what it was before. The application of this method develops a dynamic maturation system whereby the products is transferred through a system of barrels of increasing age. For this experiment, we used a highly attenuated Saison style beer, with almost 10 degrees of alcohol and a Solera system of 8 sherry barrels. The system includes the Soleras – the oldest barrel or set of barrels – and the Criaderas or nurseries. The aim is to establish a robust methodology for the production of specialty beer and present the yearly evolution results (since 2018) using microbiological, chemical, and sensory analyses.

Moderator:
Kamini Dickie, Cleverfish | cross-category beverages

Speakers:
Maureen de Wispelaere, DSM
Jens Magnus Eiken, IFF
Christophe Bellet, Brasserie Dulion
Andres Furukawa, Macken Bryggeri

This session focuses on enzymes that can facilitate brewers’ life on many fronts: making the job easier by better mastering the process, using less transformed raw materials, improving their environmental footprint by using more barley instead of malted barley, enhancing foam stability, optimizing clarity, reducing gluten content. This session will look at some concrete solutions available on the market and will balance the pros and cons, in terms of philosophy and business.

Moderator:
Maria Markus, Freelance Journalist

Speakers:
Joan Montasell, Lallemand Brewing
Roman Jove Lleixa, Peninsula Brewery
Zoran Gojkovic, Carlsberg

Building upon the 2021 Brewers Forum session on “modernizing historical and preserved beer styles”, this session will focus on the technical aspects of Kveik and how these yeast strains can be useful for brewers: heat resistance, capacity to ferment quickly and at high temperature, flavor profiles and the beer styles that can be created/imitated (i.e. “lager”) thanks to the use of Kveik yeast. Our experts will share their producers and users’ experience on these yeasts, how they work in the brewery as well as reflect whether these yeasts have a future, to what extent and if a revolution of the brewing practices is coming.

Session Chair:
Sandra Stelma (Process capacity, Agility and Futures Manager- Beer and Spirits, Diageo, IE)

Overview of biofuel fermentations – insights, parallels and contrasts with brewers’ production practices
By Zoltan Szigeti, Human Engineering
The biofuel industry is an emerging area of biotechnology, especially seen against the background of climate change. Although brewing has a much longer legacy in the field of fermentation, than the biofuel industry, the point of why this legacy should not exclude learnings from each other is a most relevant one. In this review presentation, a close look into the differences and similarities of a mainly performance oriented vs. quality-oriented processes will be provided to the audience. Of heightened interest to brewers will be a detailed comparison of fermentation kinetics in brewing vs. in biofuel fermentations, as a result of:

• Crushing and milling – particle size distribution and its yield impact;
• Mashing – fermentable to solid content process control and the potential for improving Cp and Cpk;
• Fermenting – pitching rates, enzymes, nutrition management and conversion efficiency;
• Expectations of product yield in general.

Development of a bacterial biocontrol process applicable in the barley-malt-beer industry
By Eusèbe Gnonlonfoun et al., Université de Lorraine
Pathogenic fungi represent a generic problem for cereals as they can produce a variety of mycotoxins that represent a significant concern for the malting and brewing industries, as they may affect the quality and safety of barley, malt, and beer. In order to guarantee a better hygienic and technological quality of the malt, despite the increasingly complex and variable conditions for barley production, this communication will describe the development of an innovative biocontrol process for malting facilities. It will be based on technological bacteria, isolated from infection-resistant barley cultures, that can reduce the development of spoilage fungi and the associated mycotoxin production. The experimental approach consists of: i) determining the growth kinetics of the bacterial and fungal strains by co-culturing in order to evaluate the impact of these bacteria on the fungal pathogens; ii) carrying out a micro-malting process in order to develop the aforementioned process, and iii) evaluating the technological and sanitary properties of the generated barley malts in order to validate the process developed.

The impact of long-term pitching yeast storage on viability and fermentation performance
By Carsten Zufall et al., Cervecería Polar
The purpose of this study was to evaluate which yeast storage conditions allow the pitching yeast to conserve maximum viability and fermentation performance. For that, a lager yeast cropped after a 3rd fermentation cycle was subjected to different pretreatment and storage conditions during a three-month period. Pretreatment included washing the yeast with sterile process water. Storage conditions were varied by different gassing regimes both with air or carbon dioxide. Alternatives for an activation protocol prior to fermentation were also evaluated at laboratory scale after storage. Yeast was tested weekly for viability and microbiological purity. Additionally, a laboratory scale fermentation was performed monthly to evaluate the performance of the yeast from the different trials.
Finally, the combination of the most promising pretreatment, storage conditions and re-activation technique was successfully tested on industrial scale. The availability of a large amount of pitching yeast complying with the required viability, fermentation performance and microbiological purity is a decisive advantage saving up to two weeks of run-up time after a brewery shutdown.

Archeochemistry reveals the first steps into modern industrial brewing
By Stefan Pieczonka et al., Helmholtz Institut, TUM
The molecular composition of an exceptionally well-preserved beer bottle from the German Empire era represents a unique source about the brewing culture at the end of the 19th century, when pioneer innovations laid the foundations for industrial brewing. Comprehensive analytics including metabolomics, microbiological, sensory and beer attribute analysis could certify the unprecedented good condition of the sample on a molecular level. It enabled us to decipher molecular fingerprints for technological aspects of historical beer brewing. Besides, we describe compositional changes of beer metabolites coming with long-term chemistry in such sealed complex organic mixtures (beer ageing). By the archeochemical approach, the historical production process of the beer could be traced and the ravages of time made visible.The holistic non-targeted analytical approach not only is restricted to unraveling molecular signatures and analytical marker substances for beer quality and alterations, but could highly contribute to guide modern and industrialized brewing processes such as malting (Maillard reaction), fermentation or stability during storage. (submitted as oral presentation)

Presenter:
Julieta Arevalo
Joeri De Maere

bioMérieux offers 2 solutions for the detection and monitoring of beer spoilers adapted to different sizes of breweries: VERIFLOW® for Craft and GENE-UP® BREW for Industrial. Both share the same simplicity of protocols. With these 2 technologies based on molecular biology, we make the efficiency of PCR results available to any brewery profile. Without sample enrichment or purification thanks to our patented reagents, we eliminate possible handling errors and simplify the treatment of the analysis process to the maximum. With real samples we will do a demonstration of VERIFLOW with the hop-resistant lactic acid bacteria parameter and quantitative reading of results with sensitivity of 10 cell/ml.

bioMérieux puts its technology and its experience of more than 100 years in microbiology at the service of the brewing sector.

Discover with us how easy it is to have control of your beers.

Cheers and see you soon!

Presenter:
Jesper Kailow Hejselbæk

From malt QA to digitalised fermentability consistency based on in-line mashing analysis. Having live information on the starch gelatinisation process, the development of fermentable sugars and the degree of polymerisation throughout the mashing process allows for optimisations on several parameters.

Reach RDF% consistency with suggestions on process optimisations based on machine learning.

Presenter:
Sofie Saerens

Yeast management is a crucial element of brewing good beer of consistent quality. Managing yeast to ensure certain outcomes was discovered in the late 19th century and has been utilized by the industry ever since. Having a strong, health and clean yeast is the heart of any good beer. Yet, it requires a lot of work and attention, which can be challenge in the busy breweries of today. Can this well-established practice be challenged?

Most breweries propagate yeast from slants or liquid cultures, beginning in the laboratory and growing a clean, active yeast culture in different propagation steps before pitching in the fermenters. After fermentation, the yeast is harvested from the beer and re-pitched multiple times to the next brew. This process is continued for as long as the yeast culture is determined to be healthy, clean and active.

Potential issues with this traditional propagation can be that it is time-consuming, that there might be variation in the yeast culture, leading to potential variations with the first brew as well as a risk of contamination at every additional propagation step. This results in lack of flexibility and agility in the beer production and can potentially create large bottle necks and delay of products to the market.

Therefore, Chr. Hansen has investigated how to overcome these hurdles to provide a product that: 1. Is a pure yeast culture with 2. high viability, activity and vitality of the yeast and 3. Easy to use in a flexible format. This resulted in two SmartBev™ yeast products: SmartBev™ Lager – TUM 34/70 and SmartBev™ Ale – TUM 210.

The SmartBev™ yeast have been developed in collaboration with TUM research center Weihenstephan, using some of their finest yeast and their high standards for quality insurance. The SmartBev™ yeast are designed to help the brewing industry optimize their yeast program and increase consistency in planning as well as the final beer. The product itself is delivered in a novel pouch format of frozen liquid yeast. The frozen format keeps the yeast dormant in an active state, so they are ready to start as soon as thawed. When ready to start a propagation tank, the yeast is thawed in a 30°C water bath and ready to pitch in 1 hour.

For smaller breweries where direct pitching is applied the SmartBev™ yeast can also be applied giving some of the same advantages. The main benefit reported from the craft industry is the ease of use, consistent performance, high QC standards and clean flavors in the final beer.

Therefore, the answer is yes. We believe the well-established propagation programs of yeast can be challenged and update for the benefit of the productivity, planning and the final beer quality.

Moderator:
Markus Raupach, Fotograf, Journalist, Bier-, Edelbrand- und Käsesommelier

Speakers:
Carlos Yanes, OIS&Associates
Luis Fernando Zambrano Silva, OIS&Associates
Peter Bouckaert, Purpose Brewing
Tiago Falcone, Brussels Beer Project

Beer used to ferment in and be consumed from wooden barrels until the middle of the 20th century where wooden barrels have progressively been replaced by stainless steel fermenter and kegs. However, wood – be it from the barrel or from a different form – is making a comeback in beer production. What used to be – and still is – used in wine production such as wood chips, wood dust… is now also being used in beer production which is also witnessing technical innovations that may help brewers. This session will give practical insights into the topics, with explanation by a wood product manufacturer and by the users themselves: the brewers.

Moderator:
Frits Dunnink

Speakers:
Philippe Janssens, Fermentis
Cristina Saez, B&B Brew and Spirits, S.L.
Jiri Bernat, Santa Cruz Brewery

In 2021, the Brewers Forum focused on the de-alcoholisation process to produce non-alcoholic beer. This year, the Forum looks at yeast and fermentation innovation to produce non- and low-alcoholic beers. A yeast producer will offer his expertise and how it can be applied by breweries whilst a brewer from Spain will share its success story, hopefully providing inspiration and key insights to brewers who would like to invest in that growing segment of the market.

Session Chair:
Filip Van Opstaele (Manager of the analytical centre of EFBT, KU Leuven, BE)

Application of atmospheric pressure chemical ionization gas chromatography-mass spectrometry (APGC-MS) to assess hop aromatic quality, terroir effects, and harvest maturity
By Nils Rettberg et al., VLB / TUB
From a brewers perspective minor hop volatiles (terpenoids, esters, ketones, acids, and S-compounds) appear of primary importance. They are well extracted when dry hopping, are transformed by yeast (enzymes), and impact beer flavor in very low quantities (ng/L-µg/L). The analysis of these volatiles is challenging, yet the search for analytical assays enabling effective qualification/quantification is ongoing. In the current study APGC-MS was evaluated for its use in hop volatile analysis. First, a suitable APGC-MS method was developed and the ionization parameters were optimized to yield maximum (protonated) molecular ion intensities. Successful validation was done by comparing quantitative data of 15 major hop volatiles as determined by EBC 7.12 and APGC-MS in >150 hop samples from >50 varieties. Most importantly, to evaluate the performance of APGC-MS to detect, identify, and quantify minor hop volatiles the method was applied to a unique sample set which was originally collected to study the effect of variety, maturity, and farm on hop quality metrics. By doing so, the ability of APGC-MS to enlarge the current understanding of hop chemistry is demonstrated.

Boosting release of hop-derived thiols with interspecies hybrids
By Kistoffer Krogerus et al., VTT
Interspecies hybridization has been shown to be a powerful tool for developing and improving brewing yeast in a number of industry-relevant respects. Thanks to the popularity of heavily hopped IPA-style beers, there is an increased demand from brewers for strains that can help boost hop aroma and reduce the cost impact of high hopping rates. Here, we explored whether hybridization could be used to construct strains with an enhanced ability to release hop-derived flavours through beta-lyase activity, which releases desirable volatile thiols. Wild Saccharomyces strains were shown to possess high beta-lyase activity compared to brewing strains, however, they also produced phenolic off-flavours (POF) and showed poor attenuation. To overcome these limitations, interspecies hybrids were constructed between three brewing and three wild Saccharomyces strains (S. uvarum and S. eubayanus). Hybrids were screened for fermentation ability and beta-lyase activity, and selected hybrids showed improved fermentation and formation of both volatile thiols (4MMP, 3MH and 3MH acetate) and aroma-active esters compared to the parent strains. Undesirable traits (e.g. POF) could be removed by sporulation.

Yeast and Enzymatic Release of Odorant Polyfunctional Thiols from Cysteinylated and Glutathionylated S-Conjugates
By William Donck et al., UC Louvain
In hops, 41 free polyfunctional thiols (PFTs) have been evidenced, including many sulfanylalkyl alcohols and their corresponding esters. More recently, besides the free forms, cysteinylated (Cys-) and glutathionylated (G-) adducts of PFTs have been identified in various hop cultivars at much higher concentrations. The release of PFT’s from Cys-adducts can be performed in several ways, including through primary fermentation by yeast. Incubation with apotryptophanase is also a solution to release free PFTs. Finally, chemical reactions during boiling and aging are able to release free forms of PFTs. Yet the release of PFTs from G-adducts has been less studied so far, despite their higher concentrations in hops. Two main strategies are currently investigated: either by using only selected yeasts or by incorporating exogenous enzymes. Enzymes such as gamma-glutamyl transferase are able to transform G- into Cys- adducts. In the present work, selection of efficient yeast strains (alone or mixed) and optimization of the primary and secondary fermentation parameters (wort density, temperature, duration, tank shape ..) will be investigated.

Development of thiols and thiol precursors in different hop varieties during hop harvest and their impact on beer flavor
By Christina Schönberger¸ BarthHaas
Thiols are sulfur containing aroma compounds that can exhibit, due to their very low aroma threshold, strong fruity flavors in dry hopped beers. In brewing, available scientific data is scarce. However, thiols are known to be hop variety specific. Their analysis is challenging, and the sensory importance is not unequivocal proven. We have investigated 5 different hop varieties. We have found that free thiols behave variety specific over harvest time and that the terroir effect is less important. We have also found that precursor structures decrease over harvest time with no increase in free thiols in the harvested hops. Benchtop fermentation trials and different dry hopping trials using different yeast strains show a very low impact of fermentation and dry hopping on the generation of thiols. Although both analytical and sensory data confirm the importance of the choice of a suitable combination between yeast strain and wort quality on flavor profile, sensory data shows a very low correlation with analytical data of free thiols. Further research needs to investigate the importance of wort composition to increase the potential of thiol release in brewing.

Moderator:
Jens Luckart, BierKulturHaus

Speakers:
Prof. Dr. Guido Aerts, Quality in Brewing and Distilling (QiBD)
Chris McGreger, McGregerConsulting

This practical session will be held as a one-stop-shop where brewers can come with their questions (or negative experience) around beer stability, listen to experts and then ask them the questions they are looking for an answer. It will help bring closer the science of beer stability to the day-to-day work of the brewer. Animated by two experts of the brewing process, both teaching at European universities and advising regularly small brewers, this session is the occasion to deepen your education, ask the question you never dared to ask and get answers that will really make a difference in your brewing process to improve your beers!

Session Chair:
Monica Mandrutiu (Group Head of Quality, Asahi Europe & International, RO)

Better Knowledge of Dual Hops for a Better Utilization in Late and Dry Hopping
By Cécile Chenot and Sonia Collain, UC Louvain
Over the past few decades, new dual varieties have been produced, characterised by hop cones rich in both α-acids and essential oils. Dual hops generally showed an exceptional citrus-like potential explained by either monoterpenic alcohols (such as geraniol or linalool up to 109 mg/kg) or polyfunctional thiols (41 detected up to 117 μg/kg, including the sulfanylalkyl alcohols 3SPol, 3SHol and 3S4MPol, their corresponding acetates and some aldehydes). More recently, a substantial pool of non-odorant cysteinylated (Cys-) and glutathionylated (G-) conjugates was evidenced in dual hops (G-3SHol up to 118 mg/kg and G-3S4MPol up to 4 mg/kg in Polaris, G-3SPol up to 18 mg/kg in Citra). Some of these adducts were also found in the noble hop, Saaz. In addition to seeking efficient ways to release this huge aromatic potential, identifying the S-conjugates profile of each variety will help brewers anticipate the delicate citrus/exotic flavors expected when using these cultivars. A screening of various ale and lager yeasts allowed us to identify some strains as super producers of free thiols. Lager yeasts appeared as essential to get the best of Saaz S-conjugates in premium lagers.

Deepening our Understanding of the Diastatic Power of Hops from Agronomical and Industrial Perspectives
By Thomas Shellhammer et al., Oregon State University
A prevalent topic circulating the brewing industry is the diastatic power of hops, which refer to the enzymatic activity found naturally in hop cones. Dry-hopping is the act of adding hops late in fermentation, and hop-associated enzymes may result in a dry-hop-induced refermentation of previously unfermentable beer dextrins due to the hops’ diastatic power. This study examined agronomic factors that influence hops’ enzymatic activities revealing a varietal and plant maturity dependency. Regionally, no notable changes were identified based on growing location. Hop kilning temperature (the air-on drying temperature) also influenced the hops’ enzymatic activity; with higher kilning temperatures resulting in reductions in diastatic power. Brewers have attempted to predict and prevent hop creep. We examined acidification, exogenous enzyme additions, and pasteurization as enzyme reduction strategies for the brewer, and found that pasteurizing hops had a significant impact in inhibiting hop creep. These results offer both agronomical and industrial factors that inform how we think about controlling dry-hop-induced refermentation.

Valorisation of spent hops from dry-hopping: About the potential reutilisation in the brewhouse
By Florian Schrickel et al., VLB Berlin
For many years, dry hopped beers have seen increased consumer interest and sales. The resulting spent hop material from the dry hopping process is commonly regarded as waste and hence discarded. During dry hopping, transfer rates of hop bitter acids are negligible due to the limited solubility of humulones in beer. In this study, samples of spent hop material were collected, freeze-dried and analysed for bitter acid content by HPLC. The untreated spent hops were then used as the sole source of bitter acids in the wort kettle on a 5 hl scale. Resulting worts and beers were analysed for bitter acid composition by HPLC to evaluate the formation of iso-humulone. Sensory evaluation was performed on fresh and aged beers using descriptive analysis. Humulone concentrations in the spent hops ranged from 0.9 to 10.3 % dry matter and 0.1 to 2.4 % w/w as is. Calculated retention rates of humulone in spent hops varied from 28 to 94 %. In most beer samples, the targeted bitterness was achieved. Sensory analysis gave no indication on decreased quality of beers brewed with spent hops. In conclusion, brewers can reuse spent hops as a bittering ingredient in the kettle to increase sustainability.

Impact of dry hopping on beer aroma, bitterness, color and haze: key-role and fate of terpenoids, polyfunctional thiols, esters, humulinones and flavan-3-ols in Belgian dry-hopped beers over two years of storage
By Sonia Collin and Carlos Silva Ferreira, UC Louvain
Dry hopping imparts distinct aromas, but also non-volatile compounds suspected of causing flavor and physical instability in beer. In this work, aromas, bitter compounds and flavan-3-ols, along with color and chill haze, were monitored in Belgian dry-hopped beers over 24 months of storage at 20ºC. Among the volatiles, various terpenoids, esters and polyfunctional thiols were found above their sensory thresholds in fresh samples. Unfortunately, most hop odorants were degraded after two years (only 45-57% of geraniol/linalool and 9% of polyfunctional thiols still detected). In addition, hop esterases were shown to strongly degrade fermentation esters. Humulinones were detected as important bitter compounds only in dry-hopped beers (up to 13.3 mg/L). Their poor stability through storage (73% of degradation after two years), comparable to that of trans-isohumulones, led to unpleasant compounds. Flavan-3-ol monomers, dimers and trimers were detected at high levels in dry-hopped beers (up to 6.6, 14.1 and 10.2 mg/L, respectively). While monomers from early hopping impact the color after aging, oligomers from late and dry hopping were pointed as responsible of colloidal instability.

Session Chair:
Gert De Rouck (Managing Director Pilot Malting & Brewery – EFBT, KU Leuven, BE)

Barley Varietal Impact on the Levels of Assimilable Nitrogen and Precursors for Strecker Degradation in Beer
By Xiang S. Yin et al., Rahr Malting Co.
Barley Varietal Impact on the Levels of Assimilable Nitrogen and Precursors for Strecker Degradation in Beer Xiang S Yin, Sean Tynan, Emily Del Bel, Kain Escobar, Pattie Aron Rahr Corporation, USA Based on a set of worldwide malt samples of >70 barleys from 20 plus varieties, cluster analyses demonstrated significant relationship between pattern of amino acid (AA) composition and sample origins. Substantial differences were observed in the relative content of proline (un-assimilable) between two-row (2R) and six-row (6R) varieties. In contrast to the 2R varieties, 6R samples showed a general trend of low proline and high levels of important and crucial AAs. Within 2R varieties, e.g. Metcalfe and Explorer grown in USA, the AA spectra were variety dependent. While within one variety the ratio of classes of AAs released from malt did not vary significantly with malting process, the total assimilable nitrogen varied by up to 10% depending on variety. The residual S-containing AAs impact the beer flavor profile and the Strecker Degradation AAs are key factors in the flavor stability of packaged beers, particularly all-malt brews. Impacts of heat stress on proline has been explored.

Maillard reactions in beer: 3-desoxyglucosone and flavour instability
By Melanie Kwasnicki et al., TU Dresden
During Strecker degradation, flavour active aldehydes are formed from amino acids and dicarbonyl compounds After bottling, the amount of these aldehydes increase during beer aging, thus leading to flavour instability. 3-deoxyglucosone (3-DG) is the most important dicarbonyl compound that results either from Maillard reaction or from caramelization. At beer production, malt provides a basic potential of 3-DG which increases by wort boiling. The malt modification level influences the amount of amino acids. In this study, six pale lager beers were brewed out of two barley varieties each with three different proteolytic malt modification levels. During a natural storage of nine months, precursor substances and Strecker aldehydes as well as the sensory character were analysed. It could be shown that a higher malt modification leads to higher concentrations of precursor substances like 3-DG as well as Strecker aldehydes in beer. During storage an increase of Strecker aldehydes and a decrease of 3-DG could be observed. Furthermore, de novo formation of Strecker aldehydes plays a role during ageing up to one to four months.

Untargeted metabolomic profiling of the differences between 100% malt beers and those made with unmalted barley adjunct
By David Cook et al., Nottingham University
Use of unmalted barley is an established practice in commercial brewing, which can offer cost savings, reductions in carbon and water footprints and opportunities for novel recipe development or functionality. As the proportion of unmalted barley in the grist increases, modifications to brewing protocols become necessary and the sensory properties of finished beers become distinct from those of all-malt beers. Beers brewed with 45% raw barley were characterised sensorially by a lingering bitterness and astringency. Moreover, they exhibited a lack of malty ‘fullness’ as opposed to having specific flavours imparted by raw barley. In this untargeted metabolomic study UHPLC-qTOF-MS was used to identify molecular features which differentiated unmalted barley adjunct beers from all-malt controls. This enabled identification of candidate groups of compounds which could be linked to the sensory differences between the beers, which targeted analysis of the ‘usual suspects’ (e.g. polyphenols, proanthocyanins) was not able to determine. In particular, nitrogenous fractions related to protein and purine breakdown were key differentiators and their potential sensory impacts will be discussed.

A technological measure to enhance mouthfeel in lager beers – can husk separation contribute to better beer quality?
By Jens Eiken, IFF et al.
Husk separation (also known as Kubessa process) is a well-established technique in lager beer brewing. Husk material is separated from starchy endosperm during milling and is only added back to the mash at the 72 °C rest to ensure good run-off at mash separation. This reduces the time required for polyphenols to leach into the mash. The result is an allegedly smoother and maltier beer with its bitterness originating mainly from hops, and not from any harshness imparted by the tannins or polyphenols, from the husk.  However, this technique is rarely encountered outside of Germany. The authors have investigated the reasons for adhering to such a technology both from a sensory as well as marketing point of view, based on a survey conducted among some brewers practicing husk separation. Brewing trial results conducted at Distelhäuser Brewery will be compared with a view to establishing a link between husk separation and beer polyphenol analyses. A discussion on the possible beneficial effects this technology may have on drinkability and flavour / colloidal stability will conclude the presentation.

Presenters:
Gea Van Meer
Jackie Sidhu
Jannik Munksgaard

We all know that sugar provides that great taste everyone loves so how do you answer the call for healthier beverages whilst keeping the same taste your consumers love?

Join us so we can share with you how to optimise taste thanks to our expertise in full product design for beer and beverages.

Moderator:
Laura Ulrich, Stone Brewing’s Small Batch Brewing Team / US Pink Boots Society

Speakers:
Derek Walsh, Bier Plus
Florian Schrickel, VLB Berlin

Haze can be a foe or a friend, depending on the beer styles and consumers’ expectations. This one-stop-shop session will allow brewers to hear the views of our two experts: one in beer style, another one on brewing, and better understand whether a beer must be hazy or not and then get to know how the haze can be created or avoided. The process and its impact on haze will be presented, with suggestions on how problems can be troubleshooted. Attendees will be able to ask their questions and get the answer they are looking forward. Whether haze is required for your beer or not, this session will land you with a clear and bright perspective on the topic!

Moderator:
Maurizio Maestrelli

Speakers:
Grégor Engler, Cap d’Ona
Rhodri Evans, Exponent
Julien Lefaucheux, Cap d’Ona

More and more brewers are teaming up with wine and/or spirits producers to brew beer in which spirits- or wine is added. They see that as an effort to promote the local terroir through beer, offer a new experience to consumers and further enshrine their beers in the mind of consumers. But how does it work? What should you do to produce an outstanding beer in which wine or spirits have been added? How can you market them knowing wine and spirits are heavily regulated? Our experts will share their experience in brewing such demanding products and their expertise in terms of the regulatory framework.

Session Chair:
Carsten Zufall (Head of Technology and Innovation, Cervecería Polar, VE)

Synergistic protective effects of iso-alpha-acids and xanthohumol against pathological mechanisms of liver injury
By Claus Hellerbrand and Ina Bergheim, Universität Erlangen
Iso-alpha-acids (IAA) and xanthohumol (XN) are hop derived compounds in beer. We previously demonstrated beneficial effects of IAA and XN in different models of liver disease and showed that beer causes less liver injury than pure alcohol. However, the concentrations of IAA and XN in beer are too low to fully explain the beneficial effects of moderate beer doses leading to the hypothesis that their combination may be more potent. Within the Joint ERAB EBC project grant 2018 we analyzed the combined effect IAA and xanthohumol in cell culture experiments with human liver cells called hepatic stellate cells (HSC), which play a critical role in hepatic inflammation and fibrosis, i.e. the scaring of the liver in response to injury. Low doses of IAA and XN alone showed no effects, however, the combination of the same low dosese significantly inhibited the proliferation and production of pro-inflammatory and pro-fibrogenic proteins in HSC from 12 different human donors. These data indicate a synergistic inhibitory effect IAA and XN on critical pathological mechanisms of liver injury, and thus, could be an explanation for beneficial health effect of moderate beer consumption.

Effect of xanthohumol on lipoteichoic acid-induced immune response in human peripheral mononuclear blood cells
By Ina Bergheim et al., Universität Vienna
Results of studies in rodents and in-vitro studies suggest that xanthohumol (XN), a polyphenol derived from hops, exhibits anti-inflammatory properties. Studies assessing the effect of XN in humans are limited. The aim of this placebo-controlled crossover study was to determine the effect of low doses of XN on peripheral blood mononuclear cells in humans. Subjects either randomly received orally XN or a placebo together with a standardized breakfast in a cross-over design. Before and after ingestion blood was drawn and peripheral mononuclear blood cells (PBMCs) were isolated and then stimulated with lipoteichoic acid (LTA), a bacterial toxin derived from gram positive bacteria. In the placebo group, stimulation of PBMCs with the bacterial toxin resulted in a significant increase in cytokine release. In contrast, in cells isolated after the ingestion of XN, LTA-dependent cytokine release was significantly attenuated. Taken together our data so far suggest that the intake of low doses of XN can module the LTA-induced immune response of blood cells. Acknowledgement: This project is funded within the Joint ERAB EBC project grant 2018.

Specific hop compounds inhibit the SARS-CoV-2 replication in human cells
By Sascha Venturelli et al., Universität Hohenheim
The current events in connection with the Covid 19 pandemic have made it evident that, in addition to direct vaccination protection, the targeted prevention of infectious diseases should be given a particularly high priority. Therefore, there is a search for lead structures that prevent the infection or the replication cycle of the SARS-CoV-2 virus in humans and thus impede the spread of the virus. In the investigation of natural substances, two natural constituents of hops could be identified (HI-I and HI-II), which can even be found in beer in small quantities. They minimise the replication of the SARS-CoV-2 virus in human Caco-2 cells and, for HI-I in higher concentrations, even completely prevent it. Molecular analyses were able to show an interaction of the SARS-CoV-2 virus Papain-Like Protease (PLpro) with these two hop active substances both in the computer model and in experiments with the purified enzymes. These interesting results currently serve as a basis for further investigation into the extent to which the hop constituents are suitable for the treatment of SARS-CoV-2 virus infections, either directly or as a lead structure for target specific therapeutics.

Session Chair:
Lene Bech (Senior Laboratory & Regulatory Manager, Carlsberg, DK)

Identification of key compounds affecting the property of bitterness in beer and their control
By Shunji Fujioka and Takako Inui, Suntory Japan
It is acknowledged that Bitter Units do not account for all sensory components contributing to the property of bitterness: as yet, brewing science has failed to unravel this situation. In this study, ‘Bitterness’ was deconstructed into three key components, ‘lingering’, ‘sharpness’ and ‘astringency’, and the score of ‘bitterness preference’ was negatively correlated with them by examining 14 commercial beers. Followingly, various compounds in beers, including cyclic bitter derivatives of iso -α-acid reported by Intelmann et al, were comprehensively analyzed using LC-orbitrap-MS.Then, multivariate analysis of the compounds and the sensory data was conducted. Results showed that cyclic bitter derivatives of iso -α-acid could negatively affect bitterness components. In order to control them, their behavior during wort boiling was examined. As results, their reaction kinetics were differ from those of iso -α-acid. Thus, this difference suggested that the duration of hop boiling could be used to control them. Finally, in brewing trials, shortening hop boiling indicated the decrease of those deleterious compounds: this resulted in an increase in the preferable bitterness property.

Impact of limonene degradation in beer-mix beverages on the sensory stability during shelf life
By Helmut Klein et al., Brauunion Austria
Beer-mix beverages show a different behavior during shelf life in terms of flavour stability. The staling mechanisms of beer have little relevance while the lemonade part with its strong fruity aromas is predominant. Our main interest therefore was to investigate the change of flavour substances originating from the lemonade part – especially volatile terpenes like limonene.Different types of beer-mix beverages and Radlers representing diverse flavours and alcohol levels have been investigated by multiple gas chromatographic methods as well as descriptive sensory analysis in fresh and forced aged samples. Limonene is the main aroma substance of citrus derived fruit compounds and is present in two stereoisomeric forms. During shelf life (R)-(+)-limonene shows a strong decrease whereas (S)-(-)-limonene is relatively stable. However, the (R)-(+)-limonene has a citrus like aroma whilst the (S)-(-)-limonene has a turpentine like one. In the sensory analysis of specific beer-mix beverages, we found a significant decrease of citrus-like aromas and a strong increase of soapy-turpentine flavours. This could be effected by the different stability of the limonene stereoisomers.