Beer Flavor Research Articles

Implications of Temperature Abuse on Unpasteurized Beer Quality Using Organoleptic and Chemical Analyses.

Beer flavor and sensory quality are affected by storage time and temperature due to chemical breakdown and aging. This study aimed to investigate the organoleptic properties of temperature-abused, unpasteurized craft beer and analyze the chemical breakdown associated with the process. Sensory tests were performed using a triangle test to determine consumer identification of temperature-abused beer. The chemical tests were conducted to determine the chemical breakdown of the two beer groups: control beer (COB) and temperature-abused beer (TAB). The chemical analysis of the two beer groups showed significant changes in multiple chemical compounds such as ethyl esters, linear aldehydes, and sulphur-compounds; however, the sensory analysis results were not significant even though 39% of participants were able to detect differences. in this study, two factors identified that caused chemical reactions in the TABs were oxidation and live yeast cells. In conclusion, these results can be used by beer producers to ensure a quality product throughout the distribution chain by controlling time and temperature.

Temporal Shotgun Metagenomics Revealed the Potential Metabolic Capabilities of Specific Microorganisms During Lambic Beer Production

Lambic beer production processes are characterized by a temporal succession of well-adapted microbial species. Temporal metagenomic analysis of a Belgian, traditional, lambic beer production process, which was examined microbiologically and metabolomically before, confirmed that the microbial diversity is limited. Moreover, it allowed to link the consumption and production of certain compounds to specific microbial groups or species. Fermentation characteristics, such as the conversion of malic acid into lactic acid and acetoin production, were retrieved and could be attributed to specific microorganisms, namely Pediococcus damnosus and Acetobacter species, respectively. Traits previously ascribed to brewery-specific Dekkera bruxellensis strains were confirmed during the lambic beer production process examined multiphasically; in particular, the higher production of 4-ethylguaiacol compared to 4-ethylphenol was further shown by mass spectrometric analysis. Moreover, the absence of phenolic acid decarboxylase in Brettanomyces custersianus was shown culture-independently and could explain its late occurrence during the maturation phase. Furthermore, the potential of maltooligosaccharide degradation could be ascribed metagenomically to not only Brettanomyces species but also Saccharomyces kudriavzevii, possibly explaining their degradation early in the lambic beer production process. Also, acetic acid bacteria (AAB) seemed to be able to consume maltooligosaccharides via their conversion into trehalose. Furthermore, these AAB possessed esterase genes, potentially capable of forming ethyl acetate, which may contribute to the flavor of lambic beer. Improved knowledge on the reasons behind certain community dynamics and the role of the different microorganisms in terms of potential functionality could improve brewery practices to assure to produce more quality-stable end-products.

Acetoin Biosensor Based on Acetoin Reductase-Modified Field-Effect Sensor Applied for Acetoin Detection in Beer Samples

Introduction In food industry, the use and dosing of flavoring substances is an important aspect during fabrication processes. Acetoin and diacetyl are flavoring agents which can be found in many food products, like yogurt, cheese, milk, wine and beer [1]. In beer, acetoin/diacetyl is a critical parameter for the maturation degree of the beverage during fabrication. They are formed during the first phase of beer fermentation and getting reduced during the later phase of fermentation and the maturation. Both can have a negative effect on the beer flavor, when they are above a certain concentration. Typical acetoin concentrations in beer are in the range of 10-50 µM. Measuring the acetoin/diacetyl concentration during the production can serve as a quality control and unnecessary maturation time could be avoided [2]. Until now, the quantitative determination of the acetoin/diacetyl concentration is mostly done “off-line” by gas chromatography. Therefore, a sample has to be sent to an external laboratory, which takes time till results are achieved, or the brewery needs an own laboratory, whereby enormous costs arise and trained staff is needed. Because of that, we recently developed a biosensor for the detection of acetoin based on an enzyme-modified electrolyte-insulator-semiconductor (EIS) sensor, which was characterized in buffer solutions [3]. In this work, the novel biosensor was applied for acetoin measurements in beer samples for the first time. Materials and Methods As sensor structures, capacitive Al-p-Si-SiO2-Ta2O5 field-effect sensors have been used, schematically shown in Fig. 1(a). The Ta2O5 transducer surface was modified with a novel acetoin reductase by means of cross-linking. The acetoin reductase (from B. clausii DSM 8716T) catalyzes the reduction of acetoin to 2,3-butanediol, while NADH serves as a cofactor [4]. The fabricated acetoin biosensors have been electrochemically characterized by capacitance-voltage- and constant-capacitance (ConCap) measurements in buffer solution (0.2 mM Tris-HCl) with varying acetoin concentration and beer samples, spiked with different amounts of acetoin. Results and Conclusions The acetoin sensitivity was investigated in beer solutions and the biosensors showed a linear behavior in the concentration range between 10 µM and 90 μM with a sensitivity of ca. 30 mV/dec, see Fig. 1(b). A detailed description of experiments and the obtained results will be presented and discussed.Figure 1: Schematic measurement set-up with the layer structure of the EIS sensor modified with acetoin reductase (a). Exemplary ConCap-measurement curve recorded in buffer-beer mixture (ratio 20:1) spiked with different acetoin concentrations, respectively (b). Acknowledgments The authors thank the ministry of innovation, science and research of the state of North-Rhine-Westphalia for financial support (funding program FH-Struktur 2016).

How consumer involvement influences beer flavour preferences

PurposeMuch of the innovation in the beer sector has focussed on flavour, resulting in a proliferation of flavoured beers. In this paper, the understanding of consumers’ flavour preferences is a relevant question for the beer industry; however, little is known whether consumer involvement influences beer flavour preferences, and the purpose of the present study is directed to shed light on this area yet under-investigated.Design/methodology/approachThe research was conducted in Spain, where a total amount of 565 beer consumers were classified based on their level of involvement with beer. Data were analysed by analysis of variance, Tukey test, principal component analysis and multidimensional scaling (MDS) to examine consumers’ preferences for different beer flavours using a consumer hedonic approach based on like and dislike evaluation.FindingsThe findings support the existence of a homogeneous pattern in beer-flavour preferences, regardless of consumer involvement, showing a greater liking for conventional flavours. Further, highly involved consumers show a higher preference for unconventional or flamboyant beer flavours, than low or medium involved consumers.Originality/valueDerived from the findings it can be stated that consumers do not accept all kinds of flavours and that their level of product involvement affects their flavour preferences.

Identification of the gene network modules highly associated with the synthesis of phenolics compounds in barley by transcriptome and metabolome analysis

Phenolic compounds in barley grains have an important influence on beer flavor and stability. Drought condition enhances the content of phenolics in barley grains, leading to reduced malt quality. In this study, two barley genotypes, XZ20 and XZ25 with different total phenolics content were used to investigate the effect of drought on phenolic compounds during grain developing stage. Totally, 118 phenolic metabolites were affected by drought stress. A weighted gene co-expression network analysis (WGCNA) of 17,424 highly expressed genes uncovered black (two hub genes belonged to UGT family) and turquoise modules (three hub genes belonged to phenolics pathway) that are significantly associated with the variation of phenolics. All these results reveal the changes of phenolic metabolites during grain development and provide a new insight into the regulation network of phenolic compounds under drought stress.

Low Lactic Acid-Producing Strain of Lachancea thermotolerans as a New Starter for Beer Production.

Growing consumer interest in new beer flavors is contributing to the application of innovative materials and non-Saccharomyces yeast in brewing. The goal of this study was to test the impact of the low lactic acid-producing Lachancea thermotolerans MN477031 strain on the process of fermenting beer wort, with two different concentrations of bitter compounds, and on the quality of the beer produced. Qualify factors were broadly analyzed, including ethanol content, apparent degree of fermentation, sugars, organic acids, free amino nitrogen, glycerol, volatile compounds, ions and so on. It was proven that the L. thermotolerans MN477031 strain demonstrated a high capacity for rapid initiation of wort fermentation, and a tolerance to hop-derived compounds. As a result, the alcohol content in beer from this method of production was approximately 20% lower, while the content of the real extract was significantly higher in comparison to commercial Safbrew T-58. This strain stands out from many strains of L. thermotolerans due to the low lactic acid production and only marginal influence on pH decrease compared to Saccharomyces cerevisiae. Therefore, the potential of MN477031 in the production of different types of beer (not only sour) is very high. The composition of volatile compounds in L. thermotolerans beer differs—not only in terms of the use of the strain, but also in hop variety.

Variation in Sensory Attributes and Volatile Compounds in Beers Brewed from Genetically Distinct Malts: An Integrated Sensory and Non-Targeted Metabolomics Approach

Previous research demonstrates that barley genetics can influence beer flavor. However, the chemical basis for differences in beer flavor attributed to barley is not well defined. Here, the associations between beer volatile compounds and sensory descriptors were investigated in a controlled experiment, whereby barley genotype was the main driver of variation in the system. Beer was brewed from three advanced barley breeding lines and compared to a CDC Copeland control. Sensory studies were performed via three independent panels (a consumer, brewery, and laboratory panel). The results suggest that the four beer samples have distinct flavor profiles that could be discriminated by the three sensory panels. Volatile compounds for the four beers were characterized using HS/SPME-GC-MS; quantitation and annotation were performed using a non-targeted metabolomics approach on 397 detected compounds. The O2PLS data analysis supports that alkane/alkenes, benzenoids, amides/amines, and fatty acid esters were associated with the most desirable lager traits, compared to Maillard Reaction Products that were more abundant in the beers with “non-ideal” lager traits. Taken together, these data further support the role of barley genetics in beer flavor and provide new information on the types of volatile metabolites that can vary in controlled systems.

Sourdough derived strains of Saccharomyces cerevisiae and their potential for farmhouse ale brewing

The Finnish farmhouse ale sahti is unique in that it is fermented with baking, rather than brewing strains of Saccharomyces cerevisae. The custom of maintaining farmhouse yeast cultures is however no longer practiced in Finland, and much yeast derived diversity in sahti beers has presumably been lost as a consequence. Here, the brewing potential of a number of sourdough derived strains was tested with respect to a number of different fermentation traits. Seven strains originally isolated from Finnish or Italian sourdough cultures were used to ferment high gravity sahti wort (20°P), and fermentation performance together with production of volatile compounds were assessed and compared with a reference baking yeast. Strains differed in terms of fermentation rate, yield, yeast viability and beer flavour profile. All were maltotriose positive, but utilisation varied so that alcohol yield could be greater or lower than that of the reference strain, with values ranging from 6.6 to 7.9% (v/v). Production of aroma compounds was also variable so that it was possible to identify strains producing high levels of esters and those with lower production, which could be used to emphasise flavours originating from raw materials. All strains generated 4-vinyl guaiacol and so would be suitable for other beers where this is a part of the normal flavour profile. Results suggest that sourdough isolates of S. cerevisiae are suitable for sahti production, but could also be applied to other beer styles as a way to differentiate products. © 2020 The Authors. Journal of the Institute of Brewing published byJohn Wiley & Sons Ltd on behalf of The Institute of Brewing & Distilling

Screening for the Brewing Ability of Different Non-Saccharomyces Yeasts

Non-Saccharomyces yeasts have aroused interest in brewing science as an innovative and seminal way of creating new beer flavors. A screening system for potential brewing strains of non-Saccharomyces yeasts was set up to investigate the yeast’s utilization of wort sugars and to examine the effect of hop acids as well as ethanol on the growth of different yeast strains. Additionally, phenolic off-flavor (POF) and sensory odor tests of fermented wort samples were performed. The promising strains were further investigated for their propagation ability and for following fermentation trials. The produced beers were analyzed for secondary metabolites, ethanol content and judged by trained panelists. Subsequently to the screening, it was discovered that among the 110 screened yeast strains, approx. 10 strains of the species Saccharomycopsis fibuligera, Schizosaccharomyces pombe and Zygosaccharomyces rouxii generate promising fruity flavors during fermentation and were able to metabolize maltose and maltotriose as a prerequisite for the production of alcoholic beers. Consequently, the screening method described in this study makes it possible to investigate a tremendous number of different non-Saccharomyces yeasts and to test their brewing ability in a relatively short period of time.

Investigating aroma diversity combining purge-and-trap, comprehensive two-dimensional gas chromatography, and mass spectrometry.

Headspace gas chromatography is frequently used for aroma profiling thanks to its ability to naturally exploit the volatility of aroma compounds, and also to provide chemical information on sample composition. Its main advantages rely on simplicity, no use of solvent, amenability to automation, and the cleanliness of the extract. In the present contribution, the most effective sampling (dynamic extraction), separation (multidimensional gas chromatography), and detection (mass spectrometry) techniques for untargeted analysis are exploited in combination, showing their potential in unraveling aroma profiles in fruit beers. To complete the overall analytical process, a neat workflow for data analysis is discussed and used for the successful characterization and identification of five different beer flavors (berries, cherry, banana, apple, and peach). From the technical viewpoint, the coupling of purge-and-trap, comprehensive two-dimensional gas chromatography, and mass spectrometry makes the global methodology unique, and it is for the first time discussed. A (low-)flow modulation approach allowed for the full transfer into the second dimension with mass-spectrometry compatible flow(<7mL/min), avoiding the need of splitting before detection and making the overall method sensitive (1.2-5.2-fold higher signal to noise ratio compared to unmodulated gas chromatography conditions) and selective.

Beer-spoilage characteristics of Staphylococcus xylosus newly isolated from craft beer and its potential to influence beer quality.

To meet demands for fresh flavor and unique taste from beer consumer, there is an increase in the popularity of craft beer, which is more susceptible to microbial contamination than the industry beer. A beer‐spoilage strain was isolated from craft beer and identified as Staphylococcus xylosus strain BS7. The isolate BS7 showed that high beer‐spoilage ability at low temperature (4°C), low pH (4.0) and high ethanol concentration (7.0%, v/v). Compared with the other known strains of S. xylosus, strain BS7 was resistant to hop compounds and had an evolutionary stability in hop resistance. Strain BS7 was able to grow quickly and utilizes nutrients in commercial beer, produces organic acids and biogenic amines, and changes beer flavor profile. These results suggest that S. xylosus strain BS7 is a beer‐spoilage strain with the danger, which can lead to the beer‐spoilage issues during craft beer production.

Determination of optimal sample preparation for aldehyde extraction from pale malts and their quantification via headspace solid-phase microextraction followed by gas chromatography and mass spectrometry

Aldehydes originating from malt play an important role in beer flavour deterioration. In order to better understand the influence of malting process on beer staling, it is necessary to acquire a reliable analytical methodology for determination of beer staling aldehydes in malt. Therefore, the aim of this study was to evaluate extraction parameters, which allow quantification of beer staling aldehydes present in pale malts. The method was validated with respect to linearity (R > 0.9988), limit of detection (0.28 – 0.99 μg/L), limit of quantification (0.92 – 3.31 μg/L), accuracy (± 5%), repeatability (1.3 – 5.3%) and intermediate precision (>20%). The following parameters of sample preparation were evaluated: sample amount, extraction time and temperature, ultrasonication time and oxygen level. Consequently, the best extraction conditions were successfully applied on pale malts. After extraction, the samples were analysed by headspace solid-phase microextraction (HS-SPME) with on fibre carbonyl derivatisation followed by gas chromatography and mass spectrometry (GC–MS). In addition, the salting-out effect during HS-SPME was studied. The method application allowed to identify significant differences (p ≤ 0.05) in the levels of aldehydes among various industrial scale, pale malts. The optimised method could give the information on the aldehyde content introduced into the brewing process and its potential contribution to the overall beer quality.

Higher NADH Availability of Lager Yeast Increases the Flavor Stability of Beer.

Flavor stability is a significant concern to brewers as the staling compounds impart unpleasant flavor to beer. Thus, yeasts with antistaling ability have been engineered to produce beer with improved flavor stability. Here, we proposed that increasing the NADH availability of yeast could improve the flavor stability of beer. By engineering endogenous pathways, we obtained an array of yeast strains with a higher reducing activity. Then, we carried out beer fermentation with these strains and found that the antistaling capacities of the beer samples were improved. For a better understanding of the underlying mechanism, we compared the flavor profiles of these strains. The production of staling components was significantly decreased, whereas the content of antistaling components, such as SO2, was increased, in line with the increased antistaling ability. The other aroma components were marginally changed, indicating that this concept was useful for improving the antistaling stability without changing the flavor of beer.

Gaining Entrepreneurial Insight through Mind Maps for Innovation

A critical component of the entrepreneurial mindset is the ability to be innovative and creative. Often seen as the top soft skill for entrepreneurs, innovation entails far more than brain storming. One of the most useful tools of innovation is the mind map, a simple tool that blends related and unrelated stimuli into generating new ideas. Given the increased emphasis on craft brewing as a major component of the beer industry, many facets of brewing have become quite popular in higher education. Within brewing education, one must consider the process by how students learn how to engage in multiple activities, including innovation. To address innovation in new flavors, a study of students’ abilities to create new beer flavors by brainstorming was compared with the same students who used mind maps in a pre- and post-test format. The result of the statistical study is to look at the concept of mapping innovation and the truncated findings with an emphasis on generating new ideas on beer flavors for a market with an expanding number of taste connoisseurs.

Role of Characteristic Components of Humulus lupulus in Promoting Human Health.

Over the next 50 years, the prevention and control of chronic diseases, such as obesity, cardiovascular disease, Alzheimer's disease, and many cancers, will be one of the most critical challenges in human health. Plant biochemistry and phytonutrient supplements are a promising complementary therapy for the management of chronic disease. Among them, Humulus lupulus has attracted special attention throughout the world because it contains numerous dietary phytochemicals that not only contribute to the aroma and flavor of beer but may also be used for medicinal purposes, as its properties include antiseptic, (an)aphrodisiac, anticancer, antiplatelet, antibacterial, antidiuretic, anti-inflammatory, sedative, hypnotic, and stomachic properties. This review sought to identify and understand the risk factors for chronic disease with a focus on two types of phytochemicals, bitter acids and xanthohumol. The goal was to understand how their metabolites promote human health and reduce the risk of chronic disease.

Investigation into the Potential of Lachancea fermentati Strain KBI 12.1 for Low Alcohol Beer Brewing

In brewing research, non-Saccharomyces yeasts have gained attention in recent years, owing to their potential to influence the characteristics and flavor of beer. The Lachancea genus possesses an uncommon trait, the production of significant amounts of lactic acid during alcoholic fermentation. This trait could potentially be harnessed for brewing purposes, particularly for the production of low alcohol beer. In this study, the potential of Lachancea fermentati strain KBI 12.1 was investigated for the production of low alcohol beer in low gravity wort. KBI 12.1 was characterized for sugar utilization, hop sensitivity, phenolic off-flavor (POF) production, and propagation performance. Lab scale fermentation trials in diluted wort (6.6°P) were conducted and compared to a brewers’ yeast, Saccharomyces cerevisiae WLP001. Fermentations were monitored for lactic acid and ethanol production, pH drop, and sugar consumption. In the final beers, amino acid and free amino nitrogen (FAN) content were determined and secondary metabolites were quantified. Lachancea fermentati KBI 12.1 showed to be unable to utilize maltotriose. The strain exhibited no POF production, minor hop sensitivity, and excellent propagation performance. Amino acid and FAN consumption were much lower compared to that of the brewers’ yeast. In the final beer fermented with KBI 12.1, the lactic acid concentration reached 1.3 g/L, giving the beer a sour taste. During sensory analysis, the beer was additionally described to have a fruity character. In conclusion, Lachancea fermentati KBI 12.1 proved to be a suitable strain for brewing purposes, with promising traits with regard to nonalcoholic and low alcohol beer brewing.

Extraction Efficiency of Dry-Hopping

Dry-hopping, which is the cold, aqueous extraction of hops into beer, has gained popularity in recent years as a method for achieving intense hop aroma and flavor in beer. With some brewers dry-hopping at rates up to 2 kg/hL (∼5 lb/barrel), considerable waste is generated in terms of both beer loss and spent hops. The retention of valuable volatile and non-volatile hop components within spent hops, as well as their extraction into beer, was investigated on both a pilot and industrial scale. On the pilot scale (80 L), an unhopped pale ale was statically dry-hopped with differing lots of whole cone Amarillo®, Centennial, and Cascade at a rate of 386 g/hL (1 lb/bbl) for 24 h at 13 °C (55 °F). Spent hop material was also collected from a local brewery that dry-hopped ∼60 hL (50 bbl) of beer at a rate of 1,592 g/hL (4.125 lb/bbl). Approximately one-third of the dry-matter composition of hops was lost during dry-hopping regardless of hop variety; however, there was high retention of both α-acids (77% pilot scale, 52% industrial) and hop essential oil (51% pilot scale, 33% industrial). The oil remaining in the spent hops was enriched in hydrocarbon compounds and depleted in oxygenated compounds. These results indicate that spent dry-hops contain considerable brewing value and have the potential for re-use.

Influence of Top Pressure on the Flavor and Sensorial Characteristics of Lager Beer

The top pressure of CO2 has been studied in the brewing industry as a method for improving the quality of beer. This study focused on the influence of top pressure on the flavor of lager beers by measuring different physicochemical and flavor parameters during primary fermentation and maturation. Sensorial analyses were also conducted to reveal the relationship between the instrumental data and the sensory results. Based on a detailed evaluation of the parameters and multivariate data analysis, it was demonstrated that the top pressure influenced the sensorial characteristics of lager beer by balancing the flavor in lager beers. The flavor quality was improved by altering the relative contents of the volatile compounds produced and improving the organoleptic properties of beer. On the other hand, the increased CO2 pressure slightly reduced the rate of fermentation, but its effects on the acetaldehyde and DMS content were minimal. A study on consumer preferences was also carried out to determine the possible impact of top pressure and wort gravity on the flavor quality of beers and market preferences. The maturation characteristics appeared to be improved by using a top pressure of 1.5 bar for 8°P and 0.5 bar for 12°P.

Free Amino Nitrogen in Brewing

The role of nitrogenous components in malt and wort during the production of beer has long been recognized. The concentration and range of wort amino acids impact on ethanolic fermentation by yeast and on the production of a range of flavour and aroma compounds in the final beer. This review summarizes research on Free Amino Nitrogen (FAN) within brewing, including various methods of analysis.

Enabling Heterologous Synthesis of Lupulones in the Yeast Saccharomyces cerevisiae.

Lupulones, naturally produced by glandular trichomes of hop (Humulus lupulus), are prenylated phloroglucinol derivatives that contribute the bitter flavor of beer and demonstrate antimicrobial and anticancer activities. It is appealing to develop microbial cell factories such that lupulones may be produced via fermentation technology in lieu of extraction from limited plant resources. In this study, the yeast Saccharomyces cerevisiae transformants harboring a synthetic lupulone pathway that consisted of five genes from hop were constructed. The transformants accumulated several precursors but failed to accumulate lupulones. Overexpression of 3-hydroxy-3-methyl glutaryl co-enzyme A reductase, the key enzyme in precursor formation in the mevalonate pathway, also failed to achieve a detectable level of lupulones. To decrease the consumption of the precursors, the ergosterol biosynthesis pathway was chemically downregulated by a small molecule ketoconazole, leading to successful production of lupulones. Our study demonstrated a combination of molecular biology and chemical biology to regulate the metabolism for heterologous production of lupulones. The strategy may be valuable for future engineering microbial process for other prenylated natural products.