Exploratory analysis of the volatile profile of beers by HS–SPME–GC

Kohonen Neural Network maps were used for exploratory analysis of Brazilian Pilsner beers. The input data consisted of the peak areas of the volatile profile compounds of samples obtained after headspace solid phase microextraction coupled to gas chromatography. The chromatographic peaks were identified as originating from compounds such as alcohols, esters, organic acids, phenolic compounds, ketone and others typically found in the headspace of such samples. Analysis of the Kohonen maps showed that the 20 different brands of beer could be grouped into six sets, with three of these sets having only one sample, according to the composition of their volatile fractions. The volatile species associated with the similarities and differences between each sample group were tentatively identified by mass spectrometry and their contributions to the grouping are discussed.     

The influence of wort aeration and yeast preoxygenation on beer staling processes

The influence of oxygen on the beer staling process is considered to be of major importance. Therefore, the impact of wort aeration, which is thought to cause wort oxidation processes, on beer ageing, has been examined. Pilsner and ale beers were produced with the classical wort aeration technique or by the use of the yeast preoxygenation process, in which yeast cells are exposed to oxygen before fermentation. The staling of these beers was studied using P&T GC–MS and sensory analysis. GC–MS analyses of the natural and forced aged beers showed no significant differences between the two treatments. Sensory evaluation of natural and forced beers confirmed these results. Thus, normal wort aeration (8 mg/l) does not appear to determine flavour stability in a direct manner. This is probably due to the short contact of the wort with oxygen at low temperatures before the onset of fermentation.     

The Effect of Hydroxycinnamic Acids and Volatile Phenols on Beer Quality

To the consumer, beer should be an agreeable beverage of attractive colour, clarity, pleasing flavour and should carry no toxic substances. One of the major constituents of barley is phenolic acids and their direct effect on the quality of beer is still a mystery. The aim of the study therefore was to investigate the relationship between phenolic acids during mashing at different temperatures and the quality of the beer. The mash regime and liquor to malt ratios were optimised and the carbohydrates obtained were analysed at 3.5 L of water per kg of malt and a total mash time of 105 min. Carbohydrate and phenolic acid analyses were performed by HPLC coupled with a UV‐vis detector. The three different malts used had a phenolic acid content of 33.25 μg/mL, 25.44 μg/mL and 19.98 μg/mL for malt A, B and C, respectively. The plot of 1/T versus Ln(t) gave a negative slope with activation energy (E_a) = 209 KJ/mol, rate constant (k) = 4.6 × 10^?4 mg/L min, which are comparable to similar data reported in the literature. The kinetics studies showed that the optimised mashing temperature of 90°C was adequate to form 4‐vinylguaiacol by thermal decarboxylation from the hydroxycinnamic acids. This study has shown that there is no direct correlation between phenolic acids and oxidative flavour stability of beer while the corresponding volatile phenols may affect beer flavour.     

A Semi‐Quantitative Method for the Detection of Trace Amounts of Native Collagen in Beer

Concerns about the potential allergenicity of collagen proteins remaining after beverage fining have necessitated development of methods to detect collagen in beer at very low concentrations. We have developed a semi‐quantitative SDS‐PAGE/densitometer method suitable for use in brewer's laboratories, for detection of residual native collagen at levels as low as 0.03 ppm (depending on the beer). The method is based on the fibril‐forming properties of collagen molecules at elevated ionic strength. It will not detect denatured collagens so cannot be used on pasteurised beers. For a quantitative reference that compensates for significant differences in beer composition, and the different fining agents, a known amount of the acid‐soluble fraction of the fining agent is added to the test beer to set limits of detection for the test. Densitometer results from the SDS‐PAGE gels can vary with sample volume, depending on background interference but this can be reduced by careful selection of gel loading volumes. Fining out of the added collagen occurs in some beers, so less collagen is detected in the reference samples than expected. However, as long as densitometer readings for the sample are below those of the spiked reference, then collagen levels can be declared with confidence as being less than those of the reference.     

A Review of Flavour Formation in Continuous Beer Fermentations*

The attractive prospect of a continuous beer fermentation system consists mostly of the accelerated transformation of wort into beer. Although continuous beer fermentation has been studied as a promising technology for several decades, the number of industrial applications is still limited. The major obstacle hindering the extensive industrial exploitation of this technology is the difficulty in achieving the correct balance of sensory compounds in the short time typical for continuous systems. This paper offers an integral view on the particularities of continuous systems, which may impart beer a sensorial character distinct from conventionally fermented counterparts. The main groups of flavour active compounds are discussed from the perspective of possible control strategies by means of process parameters and strain selection.     

原料对麦汁酚酸抗氧化能力的影响

本文检测了不同啤酒麦芽及酒花品种中酚酸的含量,分析了酿造原料对麦汁抗氧化能力的影响。结果发现,加麦、澳麦、国产西北三种麦芽中,澳麦提供的抗氧化能力较小,同时提供的老化物质也最少,对提高啤酒的风味稳定性有利。以单位α-酸计,香花比苦花提供更多的酚酸和抗氧化能力。酒花老化过程损失相当多的酚酸,酿造过程中应尽量使用新鲜的酒花。     

The barrel aged beer wheel: a tool for sensory assessment

There has been an increasing interest in the wooden barrel aging of beer in breweries worldwide. Monitoring of the barrel aging process relies mostly on changes in sensory parameters over time. This may be difficult for teams or brewers with little or no appropriate experience. The beer sensory wheel presents a broad approach to sensory aspects and generalised attributes for many beer styles. Accordingly, this tool may result in confusion through excessive visual information. The work reported here is based on literature research and sensory panel analysis employing ultra-flash profile with the aim to build a new visual tool for wooden barrel aged beer. This will aid the evaluation, training and quality assessment of barrel aged beer. It also provides specific terminology to describe the sensory changes during the barrel aging process. This approach was used to elucidate the characteristics of different wood species (amburana, cabreúva and American oak), and evaluate the flavour transformation of wooden barrel aged beer compared to non-aged beer. The barrel aged beer wheel comprises attributes and references for flavour evaluation and also terms that define the main transformational pathways, namely oxidation, wood extraction and biotransformation. The wheel described here is intended to meet academic and professional needs for the quality assessment of wooden barrel aged beer based on sensory analysis. © 2020 The Institute of Brewing & Distilling     

基于数字图像处理的啤酒瓶静态智能检测技术

提出了一种对再利用啤酒瓶进行质检的智能型方法—图像处理法。文中论证了啤酒瓶质量图像检测的可行性,讨论了实现检测的基本思想,论述了系统实现的基本技术路线,建立了系统构架,并分析了研究中需要关注的主要问题。该系统的研制有助于克服当前人工检测的弊端。     

重啤集团在市场经济大潮中的改革与创新

通过运用管理、技术、经营创新的理论,对重啤集团的管理、技术、经营创新模式进行了分析和论述.以实例方式阐述了管理、技术、经营创新模式在企业发展过程中所起的巨大作用,并提出了企业创新工作的原则、目标、风险防范措施.