The Impact of a Xanthohumol‐Enriched Hop Product on the Behavior of Xanthohumol and Isoxanthohumol in Pale and Dark Beers: A Pilot Scale Approach

Based on the health‐promoting properties of xanthohumol (XN), the production of an enriched beer in this substance would be of interest to the brewing industry, from the perspective of pointing out the benefits that beer could bring consumer health. For that purpose, in this work efforts were applied to produce a beer enriched in XN. Also investigated was the influence of a XN‐enriched hop product on the content of XN and isoxanthohumol (IXN) in pale and dark beers. It was verified that XN was largely converted into IXN during wort boiling. However, the use of dark malts revealed a positive effect on the thermal isomerisation of XN. These results are indicative of the isomerisation‐inhibiting effect of the stout production process, which resulted in high levels of XN in the beer. Further losses of XN were due to incomplete extraction from the hops into the wort, adsorption to insoluble malt proteins and adsorption to yeast cells during fermentation. It was possible to produce a dark beer enriched in XN (3.5 mg/L) by using coloured malt (caramel malt, roasted malt and roasted malt extract) and a special XN hop extract combined with late hop usage during wort boiling.     

新型酒花制品在啤酒工业的应用

啤酒花是啤酒工业的重要原料之一。阐述了啤酒花中3类物质即酒花树脂、酒花油、多酚物质的主要化学成分，酒花在啤酒酿造中的作用，以及酒花浸膏和酒花油等多种新型的酒花制品在啤酒工业中的应用。     

The application of metabolomics to ascertain the significance of prolonged maturation in the production of lager‐style beers

NMR‐focused metabolomic analysis has been employed to ascertain the extent to which a diversity of non‐volatile substances change in level during maturation and storage on a pilot and commercial scale. No substantive changes were observed, leading to the conclusion that, once materials such as vicinal diketones and acetaldehyde have been dealt with, there is no merit in the prolonged storage of beer. © 2019 The Institute of Brewing & Distilling     

Analysis of total polyphenols,bitterness and haze in pale and dark lager beers produced under different mashing and boiling conditions

Malting and brewing processes should be performed under process conditions in a way that minimizes beer bitterness, maximizes polyphenol content and reduces the amount of raw materials ending up in solution in the form of hazes, particles and precipitates. This work examined the influence of different mashing temperature conditions and boiling procedures on the total polyphenol content, bitterness and haze of pale and dark lager beers produced on an industrial scale. Two hop types (hop pellets and/or hop extract) and different hop varieties (Hallertau Magnum, Styrian Goldings, Saaz, Aurora and Sladek) were utilized with varying times of hop addition into the wort. Measurements of total polyphenols, colour, bitterness, alcohol content, CO₂ and pH were carried out on the beer samples. Results showed that pale lager beers had a lower total polyphenol concentration (110–179 mg/L) than dark beers (230–260 mg/L). Using hop extracts instead of hop pellets led to a lower total polyphenol concentration and to less beer foam creation. The change in the proteolytic temperature during mashing only had an influence on the total polyphenol content in the pale lager beer hopped with the pellets. Conducting proteolysis over a 20 min period led to a haze increase in all of the beers produced. In the dark beer, the haze was substantial after just 10 min at 52°C. Copyright © 2015 The Institute of Brewing & Distilling     

Influence of hop harvest date of the ‘Mandarina Bavaria’ hop variety on the sensory evaluation of dry‐hopped top‐fermented beer

To impart a special hop aroma to beer, dry‐hopping is a technique that is becoming more and more popular with commercial breweries. Nevertheless, until now little was known about the factors that influence the reproducibility (and consistent product quality) of dry‐hopping with flavour varieties. One factor that could influence the sensory impressions and aroma profile compositions of dry‐hopped beers is the hop harvest date. Therefore, to determine the effects of different harvest dates of the flavour variety ‘Mandarina Bavaria’ on the aroma of top‐fermented beer, laboratory‐scale dry‐hopping trials were performed. Besides tasting sessions of brewed beers, relative quantities of selected hop‐derived, as well as beer‐originated aroma compounds, were investigated by headspace–solid‐phase microextraction–gas chromatography–mass spectrometry. Duo–trio tests between the beers hopped with pellets of different harvest dates showed no significant differences (α = 0.05) between them. In addition, these beers had similar profiles in a five‐point profile tasting scheme. On the other hand, relative concentrations of some hop‐derived aroma compounds – especially myrcene, which is known to be able to contribute to beer flavour – increased corresponding to a later harvest date, while beer originated volatiles were not different between the beers. Analytical results combined with the results of sensory evaluations led to the conclusion that the harvest date of Mandarina Bavaria was not a dominant factor in the dry‐hopping aroma of top‐fermented beers. High amounts of fermentation by‐products are likely responsible for masking effects resulting in no sensory distinctness between the samples with different hop aroma compound concentrations. Copyright © 2016 The Institute of Brewing & Distilling     

不同光照条件对啤酒花中黄腐酚异构化影响

目的研究不同光照条件,如光照强度、光照时间、处理光的波长等因素对啤酒花中黄腐酚(xanthohumol,Xn)光异构化的影响。方法啤酒花样品在不同光照强度、光照时间、波长和不同颜色玻璃瓶储藏条件下处理后,于OD_(370)处测量Xn含量。结果相同功率光源的紫外光引起Xn异构化较白光显著(P0.05),白光照射Xn样品随着光照时间和光照强度的增大,Xn光异构化程度提高;相同功率光源及光照时间条件下,红光[(625±5)nm]、黄光[(590±5) nm]、绿光[(555±5)nm]、蓝光[(450±5)nm]处理引起的Xn异构化速度差异极显著(P0.01),其中蓝光最强,其次是绿光、红光、黄光;白光光源光照条件下,深棕色玻璃瓶储存对Xn的稳定性显著优于绿色、蓝色、无色玻璃瓶等(P0.05),并且深棕色玻璃瓶长期储存Xn显著优于绿色玻璃瓶(P0.05)。结论光照时间、波长及储存条件对Xn光异构化有显著的影响,且避光储存利于Xn稳定,这为含有Xn的饮品、食品、保健品等的光照或包装条件的选择提供了依据。     

Relationship of iso‐α‐acid content and endogenous antioxidative potential during storage of lager beer

One of the critical issues regarding the quality of beer is the change in its chemical composition that occurs during storage. Decomposition of iso‐α‐acids results in an undesirable decrease in bitterness as well as a deterioration in the sensory profile of the beer. These changes are caused by the susceptibility of iso‐α‐acids to degradation owing to the influence of reactive oxygen species and light. The aim of this study was to investigate the influence of storage conditions (temperature, light) on the degradation of iso‐α‐acids during aging, with the main focus on monitoring the relationship between the turnover of iso‐α‐acids, the sulphur dioxide content and the antioxidative potential of stored beer as measured by electron spin resonance spectroscopy. In agreement with previous investigations, a significant decrease in the content of bitter compounds (up to 18 % relative to the original level, depending on storage conditions) was observed. A significant decrease in the antioxidant potential of beer was recorded simultaneously and the data confirmed a strong correlation between these parameters. The decline in beer bitterness could become a marker for estimating oxidative damage during storage. Copyright © 2014 The Institute of Brewing & Distilling     

Fate of 2‐sulphanylethyl acetate and 3‐sulphanylpropyl acetate through beer aging

Sulphanylalkyl alcohols and their corresponding acetates were investigated in 14 commercial Belgian beers. Although it was the major peak at the pulsed‐flame photometric detector, the empyreumatic 2‐sulphanylethyl acetate was found at concentrations below its individual odour threshold, estimated at 40 µg/L (0–4 µg/L in most fresh beers, 5–12 µg/L in three fresh high‐bitter beers). Both the Ehrlich pathway and hop constituents contribute to this content. In 11 of the investigated samples, synthesis of 2SE‐A and 3‐sulphanylpropyl acetate (roasted, burned) continued during the first three months of storage. Although below their individual thresholds, these compounds might interact by synergy with other aged flavours. As yeast was absent from most of the investigated bottles, chemical degradation of precursors is suspected. Copyright © 2012 The Institute of Brewing & Distilling     

应用新技术提高啤酒的胶体稳定性

引起啤酒胶体非稳定性混浊的主要物质为蛋白质和多酚物质。可采取在麦汁煮沸阶段加入胶体物质和在贮酒过程中加入硅胶，使啤酒中的高分子蛋白质沉淀而过滤除去。利用PVPP作为多酚吸附剂对啤酒进行二级过滤，可降低啤酒中的多酚物质，也可将PVPP同硅藻土、硅胶联用过滤，降低啤酒的多酚物质。     

Current incidence of N-nitrosodimethylamine in beers worldwide

A range of beers (n = 138) from 42 countries were analysed for the presence of N-nitrosodimethylamine (NDMA) using a chemiluminescence technique with a limit of quantification of 0.1 µg L^-1. The overwhelming majority of samples (79%) did not contain detectable NDMA, and only three samples exceeded 0.5 µg L^-1. No association was found between NDMA content and beer strength, type or geographical origin. It was noted that water can be a potential source of NDMA in beverages.     

精酿啤酒专用麦芽的研究进展

在工业啤酒日趋饱和的大背景下,精酿啤酒在中国受到越来越多消费者的喜爱,并呈现出广阔的成长空间。麦芽作为精酿啤酒重要原料之一,其品质优劣决定了啤酒品质的好坏。该文结合当前精酿啤酒专用麦芽的应用研究,总结、归纳了精酿啤酒酿造用麦芽的基本种类、制麦工艺、麦芽风味物质及麦芽主要成分对啤酒品质的影响,最后阐述了精酿啤酒专用麦芽对麦芽加工工业和精酿啤酒制造业的重要意义,并对精酿啤酒专用麦芽的前景进行了展望。     

An improved HPLC method for single‐run analysis of the spectrum of hop bittering compounds usually encountered in beers

A single‐run reverse phase‐high performance liquid chromatography method for the quantification of humulinones, α‐acids, iso‐α‐acids and reduced iso‐α‐acids (where present) in commercial beer samples is presented. The method utilizes a binary solvent system consisting of (A) 1% v/v acetic acid and (B) 0.1% v/v orthophosphoric acid in acetonitrile. Separation was achieved on a Purospher® star RP‐18 column (250 × 46 mm, 3 µm) with a flow rate of 0.5 mL/min. The compounds of interest eluted within 32 min. The method was fully validated according to International Conference on Harmonization guidelines and subsequently applied to monitor degradation of hop acids in a storage trial where four lager beers were aged at 28 and 38 °C for 70 and 60 days, respectively. Results confirmed the widely reported degradation through storage of trans‐iso‐α‐acids whilst demonstrating that the HLPC method was sufficiently sensitive to monitor and model this degradation. One beer exhibited a significantly lower (P < 0.05) rate of trans‐iso‐α‐acid degradation than the other conventionally hopped beers in the study, which might have been linked to its higher pH (4.71 vs 4.36). The relative stability of reduced iso‐α‐acids during ageing was also confirmed.     

PROANTHOCYANIDIN-FREE BARLEY—MALTING AND BREWING

Colloidal haze in beer is due to the precipitation of proteins by proanthocyanidins. Carlsberg Research Center reported in 1977 that the use of barley mutants which block the biosynthesis of catechins and proanthocyanidins in the grain prevents the formation of haze in beer. The results from ten years of malting and brewing research with proanthocyanidin-free barley and malt are reviewed.     

Occurrence of sotolon,abhexon and theaspirane‐derived molecules in Gueuze beers. Chemical similarities with ‘yellow wines’

The typical Belgian Gueuze beers are produced with aged hop from a grist of malt and wheat, according to a very long oxidation process (extended boiling, cooling overnight in an open‐air container, oak‐barrel ageing). Two theaspirane‐oxidation‐derived products, dihydrodehydro‐β‐ionone and 4‐hydroxy‐7,8‐dihydro‐β‐ionone, are evidenced here for the first time in Gueuze beers. Both compounds have been recently identified in oxidative wines such as Jura Flor‐Sherry and Sauternes wines. Another analogy with Jura Flor‐Sherry wines was the presence of the nutty/curry odorants sotolon and abhexon, although at lower concentrations. Copyright © 2012 The Institute of Brewing & Distilling     

An overview of selected specialty beers: developments,challenges and prospects

The brewing industry has devoted much research effort into the development of new technologies and innovations for the expansion of the assortment of specialty beers in response to increased consumer demand. Specialty beers are more or less the catch‐all for beer styles, which do not fit into conventional beer categories and five types of specialty beers are of particular interest – low‐calorie beer, low‐alcohol or nonalcohol beer, novel‐flavoured beer, gluten‐free beer and functional beer. The selected beer types are technologically challenging to produce relative to the traditional approach of ingredient addition, yet offer special appeal to consumers from the perspective of health and flavour. Biological processes that make use of the equipment of a traditional brewery plant should be better exploited in comparison with nonbiological technologies such as thermal and membrane processes. Probiotic beer could be the specialty beer of the future in light of the increasing popularity of probiotics. These beers are reviewed in terms of developments, challenges and prospects.     

Enrichment Cultivation of Beer‐Spoiling Lactic Acid Bacteria

Various molecular methods have been developed for the rapid microbiological analysis of beer and brewing process samples. However, enrichment cultivation is still needed in order to reach the detection limits of the molecular assays, and it may directly contribute to the costs and accuracy of detection. The selection of proper enrichment cultivation conditions may be complex due to the wide variety of available media, and controversial reports of their performance. Therefore, this article aims to clarify this process by summarizing the main factors affecting the growth of lactic acid bacteria (LAB) in the enrichment cultures and reported media for this purpose.     

Detection of culturable and viable but non‐culturable cells of beer spoilage lactic acid bacteria by combined use of propidium monoazide and horA‐specific polymerase chain reaction

Current methods of detecting beer spoilage lactic acid bacteria (LAB) are time‐consuming and do not differentiate between viable and non‐viable bacteria. In this study, a combination of the conventional polymerase chain reaction (PCR) and propidium monoazide (PMA) pretreatment has been described to circumvent the disadvantages. The horA‐specific PMA‐PCR described here identifies beer spoilage LAB based not on their identity, but on the presence of a gene that is shown to be highly correlated with the ability of LAB to grow in beer. The results suggest that the use of 20 µg/mL or less of PMA did not inhibit the PCR amplification of DNA derived from viable, but putatively non‐culturable (VPNC) Lactobacillus acetotolerans. The minimum amount of PMA to completely inhibit the PCR amplification of DNA derived from dead L. acetotolerans cells was 1.5 µg/mL. The detection limit of established PMA‐PCR assays was found to be 100 VPNC cells/reaction for the horA gene. Furthermore, the horA‐specific PMA‐PCR assays were subjected to 18 reference strains, representing 100% specificity with no false positive amplification observed. In conclusion, the use of horA‐specific PMA‐PCR allows for a substantial reduction in the time required for the detection of potential beer spoilage LAB and efficiently discriminates between live and dead cells. Copyright © 2016 The Institute of Brewing & Distilling     

异构酒花颗粒在啤酒酿造中的应用研究

对异构酒花颗粒和普通酒花颗粒进行了对比研究。结果表明,添加异构酒花颗粒可减少苦味物质的损失,酿造出的啤酒优于只采用普通酒花颗粒酿造出的啤酒,特别是酒花香突出,泡特性好。