Optimisation of High Gravity and Diet Beer Production in a German Brewery by Flow Cytometry

Increasing the quantity of beer production without diminishing the quality of the product is a key concern of the beer producing industry. Modifications to the brewery's equipment and settings are the most commonly used methods to improve the brewing process, while the supreme importance of the physiological state of the beer producing organisms, the yeast cells, for the productivity of the brewing process is often poorly recognised. The work described here was designed to optimise two processes: the inoculation regime used to produce high gravity bottom-fermenting beer, and the production of high quality diet beer. To achieve these aims, flow cytometry was used to follow changes in the distribution of DNA, neutral lipid and 3β-hydroxsterol contents in Saccharomyces carlsbergensis strains during inoculation, fermentation and storage. This allowed potential time-saving alterations in the process to be identified. Double staining techniques proved that vigorous fermentative activity and long-term survival capacity during main and secondary fermentation requires intense multiplication of the yeast cells during inoculation. The production of high gravity beer was then enhanced by altering the schedule of the wort additions, and thus increasing the yeast's activities related to multiplication. To produce diet beer, oligosaccharides that remain after the standard brewing process are degraded by adding small amounts of wort, usually during secondary fermentation. However, during this period of fermentation the physiological activity of the yeast cells is hampered by low carbon and high ethanol concentrations. Adding small batches of wort at carefully defined time points and in optimised amounts, even during the main fermentation, improves the physiological state of the yeast cells and rapidly decreases the carbon concentration within the fermentation tank. Both of these factors help to promote quick fermentation to a high quality diet beer. Thus, the flow cytometric investigations provided a reliable basis for identifying effective means of improving the process regime for brewing both of these products.     

Common wheat (Triticum aestivum L.) and its use as a brewing cereal – a review

Wheat (Triticum aestivum L.) has a long tradition as a raw material for the production of malt and beer. Nevertheless, it has been studied to a much lesser extent than barley, which is the number one brewing cereal. The protein content of wheat ranges from about 6 to 20%, depending on the variety and baking characteristics, as well as on environmental conditions during growth. Since wheat is the most used cereal in the baking industry, the focus of wheat breeding and research has been about optimization for baking purposes (i.e. high protein content, stable falling numbers, constant baking qualities). It is well known that wheat varieties with a high protein content lead to problems in the brewing process. Therefore, varieties with a low protein content and with low viscosity values are favoured for malting and brewing. Since wheat beer yield has nearly doubled from 1990 to 2009, and is still increasing, more focus has been placed on conducting research on wheat for the malting and brewing industry. Currently, every tenth beer sold in Germany is a wheat beer. Therefore, it is of major interest to screen wheat varieties for brewing processability and to give more focus to wheat as a brewing cereal. In this review, a detailed characterization of wheat is given, particularly in regard to carbohydrates, pentosans, protein fractions and enzymes. The impact of wheat and its quality on the malting and brewing process is reviewed. Copyright © 2014 The Institute of Brewing & Distilling     

The Impact of Malt Derived Proteins on Beer Foam Quality. Part II: The Influence of Malt Foam-positive Proteins and Non-starch Polysaccharides on Beer Foam Quality

Pilot (50 litre) and small scale (700 mL) brewing trials conducted using, similar brewing protocols with 25 different malts, indicated that differences in malt quality influenced foam stability (Rudin head retention value) by up to 24%. In addition to conventional measures of malt quality, enzyme-linked immunosorbent assays (ELISA) were used to measure the level of the putative foam-positive proteins, BSZ4 (protein Z4), BSZ7 (protein Z7), BSZ7b and lipid transfer protein 1 (LTP1). Regression analysis performed on the combined pilot and small scale data sets identified that malt BSZ4, wort β-glucan and wort viscosity, and beer protein, β-glucan and arabinoxylan were positively correlated with foam stability, while malt Kolbach index (KI), and beer FAN were negatively correlated with foam stability. Potentially foam-positive proteins such as BSZ7 and LTP1 were not correlated with foam stability. The negative correlation of BSZ4 level with KI suggested an additional role for BSZ4 in influencing protein modification. Step-wise multiple regression indicated that up to 82% of the variation in foam stability could be predicted from the malt and beer characteristics measured, demonstrating that there are a number of inter related malt derived factors that influence beer foam stability.     

发酵环境变化对酵母生长和成品啤酒的影响

啤酒发酵是一个复杂的生物和物质转化过程,在整个酿造过程中,从原料粉碎到开始发酵直至发酵结束降温冷贮,环境变量因素很多,会影响啤酒酵母生长,从而影响成品啤酒中的挥发性风味物质和啤酒品质。该文重点总结介绍麦汁浓度、接种率、发酵温度、压力变量对发酵过程的影响,旨在为解决啤酒酿造过程可能出现的问题提供一些思路,从而提高啤酒质量。     

Comparison of beer quality attributes between beers brewed with 100% barley malt and 100% barley raw material

BACKGROUND: Brewing with 100% barley using the Ondea^® Pro exogenous brewing enzyme product was compared to brewing with 100% barley. The use of barley, rather than malt, in the brewing process and the consequences for selected beer quality attributes (foam formation, colloidal stability and filterability, sensory differences, protein content and composition) was considered. RESULTS: The quality attributes of barley, malt, kettle‐full‐wort, cold wort, unfiltered beer and filtered beer were assessed. A particular focus was given to monitoring changes in the barley protein composition during the brewing process and how the exogenous OndeaPro^® enzymes influenced wort protein composition. All analyses were based on standard brewing methods described in ASBC, EBC or MEBAK. To monitor the protein changes two‐dimensional polyacrylamide gel electrophoresis was used. CONCLUSION: It was shown that by brewing beer with 100% barley and an appropriate addition of exogenous Ondea^® Pro enzymes it was possible to efficiently brew beer of a satisfactory quality. The production of beers brewed with 100% barley resulted in good process efficiency (lautering and filtration) and to a final product whose sensory quality was described as light, with little body and mouthfeel, very good foam stability and similar organoleptic qualities compared to conventional malt beer. In spite of the sensory evaluation differences could still be seen in protein content and composition. Copyright © 2011 Society of Chemical Industry     

Transfer of Fusarium mycotoxins and ‘masked’ deoxynivalenol (deoxynivalenol-3-glucoside) from field barley through malt to beer

The fate of five Fusarium toxins — deoxynivalenol (DON), sum of 15- and 3-acetyl-deoxynivalenol (ADONs), HT-2 toxin (HT-2) representing the main trichothecenes and zearalenone (ZON) during the malting and brewing processes — was investigated. In addition to these ‘free’ mycotoxins, the occurrence of deoxynivalenol-3-glucoside (DON-3-Glc) was monitored for the first time in a beer production chain (currently, only DON and ZON are regulated). Two batches of barley, naturally infected and artificially inoculated with Fusarium spp. during the time of flowering, were used as a raw material for processing experiments. A highly sensitive procedure employing high-performance liquid chromatography coupled with tandem mass spectrometry (LC-MS/MS) was validated for the analysis of ‘free’ Fusarium mycotoxins and DON-conjugate in all types of matrices. The method was also able to detect nivalenol (NIV), fusarenon-X (FUS-X) and T-2 toxin (T-2); nevertheless, none of these toxins was found in any of the samples. While steeping of barley grains (the first step in the malting process) apparently reduced Fusarium mycotoxin levels to below their quantification limits (5–10 µg kg^?1), their successive accumulation occurred during germination. In malt, the content of monitored mycotoxins was higher compared with the original barley. The most significant increase was found for DON-3-Glc. During the brewing process, significant further increases in levels occurred. Concentrations of this ‘masked’ DON in final beers exceeded ‘free’ DON, while in malt grists this trichothecene was the most abundant, with the DON/DON-3-Glc ratio being approximately 5:1 in both sample series. When calculating mass balance, no significant changes were observed during brewing for ADONs. The content of DON and ZON slightly decreased by a maximum of 30%. Only traces of HT-2 were detected in some processing intermediates (wort after trub removal and green beer).     

Fungal Hydrophobins in the Barley‐to‐Beer Chain

Fungal hydrophobins have been shown to induce gushing of beer. In order to study the occurrence and fate of hydrophobins at different stages of the production chain of beer, barley samples artificially infected in the field with Fusarium culmorum, F. graminearum and F. poae were collected during the growing period as well as during various stages of the malting process. In addition, naturally infected malt was brewed in pilot scale and samples were collected throughout the process. The samples were assayed for hydrophobin content using an ELISA method. The results showed that fungi produced hydrophobins that accumulated during barley grain development in the field, but that production was more pronounced during malting. Prolonged storage of barley tended to reduce the ability of fungi to produce hydrophobins in malting. Studies on the fate of hydrophobins during the brewing process revealed that mashing released hydrophobins from the malt into the wort. Some loss of hydrophobins occurred throughout the brewing process with spent grains, cold break (wort boiling) and surplus yeast. In addition, the beer filtration step reduced hydrophobin levels. Despite the substantial loss of hydrophobins during brewing, the level was high enough to induce the gushing detected in the final beer.     

Changes in crude arabinoxylan during cloudy wheat beer brewing on a production scale

As one of the major non‐starch polysaccharides in the cloudy wheat beer, arabinoxylan has a crucial influence on the wort viscosity, foam profile and stability of the beer. In this study, the cloudy wheat beer was fermented on a production scale with a ratio of barley to wheat malt of 1:1, during which the changes in arabinoxylan were monitored in order to determine the key steps which influence the content, substitution degree of arabinoxylan (A/X) and average degree of polymerization (avDP) value of crude arabinoxylan during cloudy wheat beer brewing. The results show that the total contents of crude arabinoxylan, arabinose, xylose and galactose increased until the end of mashing and then dropped with the addition of spent grain sparging water. The crude arabinoxylan decreased during the saccharification, and then stabilized at ~10.00 mg/g. During fermentation and storage, the content of crude arabinoxylan did not change remarkably. The A/X remained at ~0.50 in the process of wort preparation and brewing and the avDP value of crude arabinoxylan decreased during saccharification and then stayed at ~3.00 in the fermentation and storage phases, which was lower because the contents of free arabinose, xylose and galactose were not subtracted from the total contents of the sugars. Therefore, wort preparation is shown the key step influencing the changes in crude arabinoxylan during cloudy wheat beer brewing. Copyright © 2017 The Institute of Brewing & Distilling     

ENTEROBACTER AGGLOMERANS—A NEW BACTERIAL CONTAMINANT ISOLATED FROM LAGER BEER BREWERIES

From a large number of bacterial strains isolated from all stages of the brewing process in four different beer breweries in South Africa, fifty-five bacterial strains were identified as Enterobacteriaceae by phenotypic analysis. All enterobacterial species previously reported in brewery samples, as well as eighteen strains of Enterobacter agglomerans were found. E. agglomerans strains were isolated from pitching yeast and fermenting wort samples. The occurrence of E. agglomerans in pitching yeast is significant and indicates that these bacteria survive the brewing process. E. agglomerans is regarded as a potential beer spoilage contaminant in lager beer breweries.     

Optimization of alcohol‐free beer production by lager and cachaça yeast strains using response surface methodology

Alcohol‐free beers (AFBs) are an attractive segment of the beer market both for the brewing industry and for consumers. While AFBs produced by arrested/limited fermentation often suffer from a lack of volatile compounds, beer flavour can be improved by yeast selection and optimization of fermentation conditions. The yeast selection strategy was demonstrated by comparing traditional lager yeast with selected cachaça yeast strains. Correspondingly, response surface methodology was used to enhance the formation of the flavour‐active volatile compounds by optimization of the fermentation conditions (original wort extract, fermentation temperature, pitching rate). Statistical analysis of the experimental data revealed the relative significance of process variables and their interactions. The developed quadratic model describing the responses of total esters and higher alcohols to changes in process variables was used to predict the ideal fermentation conditions in terms of flavour formation. The predicted conditions were experimentally verified and alternative strategies of AFB production are suggested. Copyright © 2016 The Institute of Brewing & Distilling     

酒花中萜烯醇类化合物的研究进展

酒酒花添加可赋予啤酒特有的风味,使酒体丰满协调。萜类物质对酒花风味的贡献发挥着重要作用。其中,萜烯醇类物质（如里那醇、香叶醇、β-香茅醇、α-萜品醇、橙花醇等）是影响酒花香气的关键性成分,其在发酵过程中含量的微小变化对啤酒的品质及感官评价影响很大。啤酒中的萜烯醇类物质不仅与酒花品种有关,还与发酵过程中的生物转化有关,甚至在储存时期也有变化。了解酒花中的萜烯醇类香气化合物在啤酒酿造过程中的含量及变化规律与控制和稳定啤酒的风味质量密切相关。该文就酒花中萜烯醇类物质的国内外研究现状做一综述。     

COLD STERILE FILTRATION: A SMALL SCALE FILTRATION TEST AND INVESTIGATION OF MEMBRANE PLUGGING

Beer brewed from 24 commercially and bag malted samples by a small scale brewing method was assessed by a micro-filtration efficiency (MFE) test designed to emulate the cold-sterile (membrane or micro-) filtration process. The level of malt derived beer components with the potential to reduce MFE, such as β-glucan, arabinoxylan, protein and polyphenol, were consistent over duplicate beer batches suggesting that beer quality was reproducible using the small scale method. The small scale MFE test was able to differentiate (P<0.001) between beer brewed from distinct malt samples in a reproducible fashion, suggesting that the test is effective in assessing beer MFE in the laboratory. Subsequently, the effects of various malt derived beer components on micro-filtration were investigated. MFE (measured as <i>V_max) was negatively correlated with beer arabinoxylan content (r=–0.62, P<0.01), suggesting that the arabinoxylan content of malt, and subsequently beer, may influence MFE. Total beer β-glucan was not significantly related to beer MFE (r=-0.36). However, it was likely that β-glucan molecules of high molecular weight influenced MFE more so than the total β-glucan content. Beer viscosity, which was correlated to both beer β-glucan and arabinoxylan content (r=0.86, P<0.001 and r=0.68, P<0.05, respectively), correlated with V_max (r=-0.81, P<0.001) .     

Suitability of unmalted quinoa for beer production

BACKGROUND

This study provides the first detailed investigation into the effect of partially substituting barley malt with quinoa (Chenopodium quinoa Willd.) on the characteristics of wort and beer. Quinoa seeds and flakes were compared in terms of their suitability for brewing. The benefits of applying a commercial enzyme mixture during beer production with quinoa were also investigated.

RESULTS

These findings show that quinoa is a good starchy raw material for brewing. Even without exogenous enzymes, it is possible to substitute barley malt with up to 30% quinoa. The form in which quinoa is used has a negligible influence on the quality of the wort and beer. The foam stability of beer made with quinoa was better than that of all‐malt beer, despite there being a lower level of soluble nitrogen in quinoa beer in comparison with all‐malt beer and more than twice the amount of fat in quinoa in comparison to barley malt.

CONCLUSION

The addition of unmalted quinoa does not give unpleasant characteristics to the beer and was even found to have a positive effect on its overall sensory quality. This offers brewers an opportunity to develop good beers with new sensory characteristics. © 2018 Society of Chemical Industry     

浅析生产中影响啤酒泡沫的几个因素

啤酒的泡沫性能包括起泡能力、泡沫外观、泡沫持久性和泡沫挂杯4个方面。影响啤酒泡沫形成的因素主要有原料的质量、制麦工艺、糖化工艺、发酵工艺、贮酒时间长短、过滤与灌装的温度和压力以及杀菌时间。实现啤酒较好的泡沫性能,首先控制原料及生产过程中蛋白质的分解;其次是保证生产后期泡沫质量稳定。（孙悟）     

Humulus lupulus – a story that begs to be told. A review

The hop cones of the female plant of the common hop species Humulus lupulus L. are grown almost exclusively for the brewing industry. Only the cones of the female plants are able to secrete the fine yellow resinous powder (i.e. lupulin glands). It is in these lupulin glands that the main brewing principles of hops, the resins and essential oils, are synthesized and accumulated. Hops are of interest to the brewer since they impart the typical bitter taste and aroma to beer and are responsible for the perceived hop character. In addition to the comfortable bitterness and the refreshing hoppy aroma delivered by hops, the hop acids also contribute to the overall microbial stability of beer. Another benefit of the hop resins is that they help enhance and stabilize beer foam and promote foam lacing. In an attempt to understand these contributions, the very complex nature of the chemical composition of hops is reviewed. First, a general overview of the hop chemistry and nomenclature is presented. Then, the different hop resins found in the lupulin glands of the hop cones are discussed in detail. The major hop bitter acids (α‐ and β‐acids) and the latest findings on the absolute configuration of the cis and trans iso‐α‐acids are discussed. Special attention is given to the hard resins; the known δ‐resin is reviewed and the ε‐resin is introduced. Recent data on the bittering potential and the antimicrobial properties of both hard resin fractions are disclosed. Attention is also given to the numerous essential oil constituents as well as their contributions to beer aroma. In addition to the aroma contribution of the well‐known essential oil compounds, a number of recently identified sulfur compounds and their impact on beer aroma are reviewed. The hop polyphenols and their potential health benefits are also addressed. Subsequently, the importance of hops in brewing is examined and the contributions of hops to beer quality are explained. Finally, the beer and hop market of the last century, as well as the new trends in brewing, are discussed in detail. Hop research is an ever growing field of central importance to the brewing industry, even in areas that are not traditionally associated with hops and brewing. This article attempts to give a general overview of the different areas of hop research while assessing the latest advances in hop science and their impact on brewing. Copyright © 2014 The Institute of Brewing & Distilling     

果酿啤酒的酿造工艺和品质研究进展

果酿啤酒的品质受众多因素影响,特别是水果特性差异和产品质量标准缺失使得果酿啤酒的酿造工艺存在较大差别,产品质量难以稳定。为进一步提升果酿啤酒品质,该文对近年来果酿啤酒的研究现状进行综述,探讨水果榨汁处理、灭菌方式,发酵过程中原麦汁浓度、主发酵温度、果汁添加量及添加阶段、酵母菌种选择等因素对果酿啤酒品质的影响,分析果酿啤酒的风味成分及风味劣变、活性成分及抗氧化活性,并对果酿啤酒的发展趋势及品质提升进行展望,以期实现不同果酿啤酒的精准调控,为实际生产中果酿啤酒的酿造提供借鉴。     

Construction of recombinant industrial <Emphasis Type="Italic">S. cerevisiae</Emphasis> strain with barley lipid-transfer protein 1 secretion capability and lower PrA activity

Beer barley LTP1 in beer is an important component of beer foam, and it participates in the formation of beer foam. The digestion of beer barley LTP1 by proteinase A from brewing yeast leads to the decline of beer foam stability, especially for the unpasteurized beer. The objective of this study was to construct an industrial brewing yeast strain to secrete recombinant barley LTP1 into fermenting wort during beer fermentation for the foam stability improvement. We constructed barley LTP1 expression cassette and transformed into the host industrial yeast cells to replace partial PEP4 alleles using homologous recombination method. The expression of b-LTP1 was under control of the constitutive yeast ADH1 promoter, and the concentration of recombinant barley LTP1 secreted by recombinants reached 26.23 mg/L after incubation in YEPD medium for 120 h. The PrA activity of the recombinant strain declined compared with the host strain. The head retention of beer brewed with the recombinant industrial strain (326 ± 12 s) was improved when the host strain WZ65 (238 ± 7 s) and the constructed strain S.c-P-1 (273 ± 10 s) with partial PEP4 gene deficiency were used as control. The present study may provide reference for brewing industries and researches on beer foam stability.     

Investigating the Antimicrobial Efficacy of a Lactococcal Bacteriocin for the Development of Microbiologically Stable Beer

Barley isolate Lactococcus lactis M30 produces an antimicrobial proteinaceous activity, which at least under laboratory conditions was shown to target beer spoiling lactic acid bacteria, including Lactobacillus brevis BSH9. The aim of this study was to investigate the application of this antibacterial activity at various stages of the brewing process and in packaged beer. Lactococcus lactis M30 was shown to produce the antimicrobial activity during growth under specific conditions in fortified unhopped wort. However, this activity was lost during wort boiling and yeast fermentation. When the bacteriocin was added directly to beer it retained in vitro activity following pasteurisation, while it was also shown to inhibit growth in situ when pasteurised beer was challenged with low levels of the beer spoiling Lactobacillus brevis BSH9 culture. The capacity of the bacteriocin to prevent microbial spoilage of beer was tested at various temperatures over a period of seven weeks. Storage of bacteriocin‐containing beer at 30°C or room temperature resulted in a decrease in antimicrobial activity over time, but when refrigerated or frozen, this beer retained sufficient activity to be effective against Lactobacillus brevis BSH9.     

Influence of sorghum grain type on wort physico‐chemical and sensory quality in a whole‐grain and commercial enzyme mashing process

To determine the most suitable types of sorghum for whole‐grain adjunct in lager beer brewing, 14 cultivars of five different types: white tan‐plant, white non‐tan‐plant, red non‐tannin, white tannin (type II) and red tannin (type III) were evaluated. The effects of grain type on wort physico‐chemical and sensory quality with raw grain and malt plus commercial enzyme mashing were assessed. Tannin content correlated significantly and negatively with wort extract and fermentable sugars (p < 0.001) and free amino nitrogen (FAN; p < 0.1). This is attributable to inactivation of the exogenous enzymes by the tannins during the mashing process. However, the type II tannin sorghums had wort quality attributes closer to the non‐tannin sorghum types, probably owing to their relatively low tannin content (≤1%). Malting gave a great improvement in wort extract, fermentable sugars and FAN, but substantially influenced wort sensory properties in terms of higher sourness, bitterness and astringency, as well as the expected more malty flavour. Worts from raw red non‐tannin sorghums were similar to those of white tan‐plant sorghums in both physico‐chemical and sensory quality. Thus, red non‐tannin sorghums, in view of their better agronomic quality, have considerable potential as a whole‐grain adjunct in lager beer brewing. Copyright © 2013 The Institute of Brewing & Distilling