高浓麦汁中添加红枣汁对酵母发酵性能及啤酒风味的影响

该实验研究了红枣汁不同添加量（10%、15%、20%、25%、30%、35%）对啤酒高浓酿造中酵母发酵性能及风味物质的影响。结果表明,红枣汁的添加能显著提高酵母的发酵性能,发酵过程中红枣汁添加组总CO2质量损失均高于对照组,发酵结束后乙醇产量显著增加（P＜0.05）,其中,30%红枣汁添加量促发酵效果最好,发酵度为88.18%,酒精度为11.30%vol,与对照组相比,分别提高了4.16%和4.63%。添加红枣汁可显著影响啤酒的色值：红枣汁添加比例越高,啤酒L*值越低,a*值与b*值越高,总色差（ΔE值）与对照组差异越大。与对照组相比,红枣汁的添加减少了高级醇的形成,显著降低了啤酒的醇酯比。     

Rotary jet head – a device for accelerating the fermentation process in brewing

The world beer market is dominated by lagers, with production estimated at hundreds of millions of hectolitres per year. The vast majority of the beer is produced using CCT (cylindro‐conical tank) technology. Fermentation and maturation are time‐consuming processes and the bottlenecks of beer production. A rotary jet head (RJH) – a device originally used as a cleaning device – is proposed for use as a tool to provide homogeneity in the tank and to increase the activity of the yeast cells by keeping them in suspension during the fermentation process. The main objective of the study was to analyse the impact of mixing the content of the fermentation tank (by the means of an RJH) on the time of fermentation, maturation and cooling. The experiments were carried out under full industrial operational conditions. It was concluded that mechanical mixing, in a CCT of 3800 hL, shortened the time of lager beer production process by ca. 15%, the time of fermentation by ca. 24 h and the cooling time by ca. 35 h. Copyright © 2016 The Institute of Brewing & Distilling     

超声波辐照工艺在酒类发酵中的应用

在啤酒、葡萄酒和清酒的发酵过程中,啤酒酵母(Saccharomyces cerevisiae)会产生各种物质,如醋酸异戊酯及其他酯类,为最终产品提供香味;然而,期间不断增加的溶解二氧化碳(DCO_2),却会抑制乙醇和酯类的生成。因此,减少发酵阶段的DCO_2水平,即能有效地提高乙醇产品的质量,同时,发酵时间也得以大幅度的缩短。 要降低发酵过程中DCO_2的水平,采用超声波辐照处理是一个有效的途径。日本大关(株)综合研究所松浦一雄等人在这方面进行了研究,证明超声波辐照工艺在葡萄酒、啤酒和清酒发酵中均能够起到正面的作用,本文将就这方面作出探讨。     

Formation of 4‐Hydroxyfuranones and their Precursors during Production of Worts and Beers

Laboratory beers and samples taken at each stage of production, were analysed for the flavour active 4‐hydroxyfuranones; 5‐methyl‐4‐hydroxy‐3(2H)‐furanone (MHF), 2,5‐dimethyl‐4‐hydroxy‐3(2H)‐furanone (DMHF) and 5‐(or 2)‐ethyl‐2(or 5)‐methyl‐4‐hydroxy‐3(2H)‐furanone (EMHF). The length and temperature of mashing, the length of boiling, the rate of cooling the worts and the effects of grist composition were investigated to identify the 4‐hydroxyfuranone content of worts and subsequent beers. Fermentation temperature and the use of the stabilising agents, PVPP and Lucilite PC5, on the 4‐hydroxyfuranone content of the beer was also investigated. The results demonstrated that several aspects of beer production procedures affect the furanone content of the beer, but in practice the important factors are grist composition, the rate at which the boiled wort is cooled and fermentation temperature. Fermentation has a major effect on final furanone content as yeast produces both DMHF and EMHF. The results suggest that malt levels of precursor compounds, which can be converted to 4‐hydroxyfuranones by the Maillard reaction or by yeast, may prove to be more important than the quantities of the furanones found in malt in determining the final furanone content of beer. A clearer understanding of the nature of the precursors should allow manipulation of their production and beer furanone content.     

基于计算流体力学对啤酒发酵罐的模拟

利用计算流体力学模拟技术对不同高径比的350 m3锥形啤酒发酵罐进行数值模拟。模拟结果表明,在啤酒发酵冷却降温过程中,不同高径比的锥形发酵罐在相同条件下罐内温度分布情况明显不同,高径比为3∶1～4∶1时降温效果更好。不同发酵罐内的速度分布也存在明显差异,除了高径比为2:1的发酵罐存在一个整体的循环对流外,其他发酵罐内发酵液均以局部小涡流的状态存在。通过对不同高径比的发酵罐内的温度场和速度场的分析,可以为啤酒发酵罐的选型提供一定的理论依据。     

A Comparative Study of Stout Beer Batch Fermentation Using Free and Microencapsulated Yeasts

Because many questions arise regarding the use of immobilization technology to consistently produce a high quality beer, this work focuses on the effects of using an immobilization matrix in the fermentation process. The aim of this study was to explore the feasibility and potential uses of immobilization on sensorial characteristics such as color, flavor, and headspace compounds of stout beer, when using batch fermentation. Batch production of beer was conducted as a standard ale process for stout beer production. For the immobilized yeasts fermentation, cells were microencapsulated in alginate, by using the Thiele modulus procedure for microcapsule design. Glucose concentration, cell multiplication, cell viability, specific gravity, pH, Brix, and ethanol were monitored throughout the fermentation process. Both, sensorial analysis (statistic triangle tests) and instrumental methods (gas chromatography to measure headspace compounds and visible spectrophotometer to quantify the color) were used to evaluate characteristics of the beer that was produced from immobilized and free yeast fermentations. Free and immobilized yeasts fermentation showed no significant difference (p > 0.05) for all variables of interest. The profile of headspace compounds was different, perhaps because of changes in yeast’s behavior and the presence of secondary metabolites. However, immobilization did not have a significant impact on the beer flavor, as detected by the sensorial triangle test.     

基于啤酒发酵工艺的制冷系统冷负荷算法

冷负荷是设计制冷系统的基本条件.本文在啤酒发酵生产过程温度与时间工艺曲线的基础上,经过详细分析得到发酵冷负荷的计算方程式,并由此提出了稳定生产时发酵工艺冷负荷与工艺时间无关的结论.在工程上本文有助于减小冷冻站的设计误差,对啤酒厂制冷系统的科学设计具有一定的参考价值.     

Fed‐batch fermentation with glucose syrup as an adjunct for high‐ethanol beer brewing

To produce a beer with a high ethanol content, preliminary research on fed‐batch fermentation profiles with glucose syrup as an adjunct during the primary fermentation period was conducted. The ethanol concentration of the beer was elevated by feeding a glucose syrup into the fermentors at a later stage of primary fermentation. Fermentation trials were carried out using a typical lager strain, SC‐9, with a pitching rate at 7.0 × 10⁶ cells/mL. An all‐malt wort (12.5°P) was employed and the primary fermentation temperature was 14 °C. Glucose syrup was supplemented when the concentration of residual reducing sugars was decreased to ~10 g/L. Results showed that the supplemented glucose was consumed rapidly and that the ethanol concentration in the final beer was raised to 67.9 g/L. Additional growth of yeast was observed after feeding accompanied by a low yield of ethanol (~0.46 g/g). Formation of diacetyl was enhanced by yeast growth and two additional peaks were obtained after feeding. The peak value of the diacetyl concentration was 1.90 mg/L. The fed‐batch fermentation resulted in a beer with an overproduction of higher alcohols and esters, indicating that brewing under these experimental conditions led to an unbalanced flavour profile. Results of optimization demonstrated that the optimal conditions were found to be 15°P for initial wort extract, 10 °C for fermentation temperature and 20 × 10⁶ cells/mL for yeast pitching rate, leading to total higher alcohols of 173.8 mg/L, total esters of 22.8 mg/L and an acetaldehyde concentration of 40.5 mg/L. A 12 day maturation and fermentation temperature of 8 °C was needed to reduce the acetaldehyde to 14.3 mg/L. Copyright © 2014 The Institute of Brewing & Distilling     

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。     

玫瑰香槟啤酒的研制

采用瓶内二次发酵的方法,以玫瑰和麦芽为原料研制出一种具有特殊风格的玫瑰香槟啤酒。研究了玫瑰浸提的技术参数,探讨了玫瑰香槟啤酒的酿造工艺条件。结果表明:玫瑰花的最佳浸提条件为:料水比1∶60,浸提温度80℃,浸提时间1.5 h。玫瑰香槟啤酒的酿造条件为:玫瑰浸提液与啤酒原酒以40∶60的比例配比,接入2%的香槟酵母,加4%的糖,进行低温二次发酵,发酵6 d,得到的产品气泡含量丰富、残糖少、香气协调柔和,风味品质俱佳。     

一株质粒转导纤溶酶基因工程菌株在啤酒发酵中的特性

研究了1株通过质粒转导而获得纤溶酶基因的下面发酵酵母在啤酒发酵中的特性,并进行规模为5L的啤酒发酵试验,对啤酒主发酵过程中5个主要影响指标—PH值、双乙酰、酒精度、实际发酵度、总还原糖进行了测定。结果表明,各项指标与对照菌株相比差异较小,且都在正常范围之内,具有可应用于保健啤酒生产的潜能。     

Screening for new brewing yeasts in the non‐Saccharomyces sector with Torulaspora delbrueckii as model

This study describes a screening system for future brewing yeasts focusing on non‐Saccharomyces yeasts. The aim was to find new yeast strains that can ferment beer wort into a respectable beer. Ten Torulaspora delbrueckii strains were put through the screening system, which included sugar utilization tests, hop resistance tests, ethanol resistance tests, polymerase chain reaction fingerprinting, propagation tests, amino acid catabolism and anabolism, phenolic off‐flavour tests and trial fermentations. Trial fermentations were analysed for extract reduction, pH drop, yeast concentration in bulk fluid and fermentation by‐products. All investigated strains were able to partly ferment wort sugars and showed high tolerance to hop compounds and ethanol. One of the investigated yeast strains fermented all the wort sugars and produced a respectable fruity flavour and a beer of average ethanol content with a high volatile flavour compound concentration. Two other strains could possibly be used for pre‐fermentation as a bio‐flavouring agent for beers that have been post‐fermented by Saccharomyces strains as a consequence of their low sugar utilization but good flavour‐forming properties. Copyright © 2015 John Wiley & Sons, Ltd.     

奶啤生产中乳酸菌对酵母菌发酵作用的研究

利用乳酸菌和酵母菌的共生作用,对牛乳进行了混合菌种的发酵研究。分析了共生作用对产品pH值、滴定酸度、乙醇含量和α-氨基酸态氮的影响。研究结果表明,乳酸菌的加入不仅可以提高酵母菌的生长速度,而且可以提高产品的风味,奶啤的酒精含量相对啤酒较低,是酒精度较低的健康型饮料。     

啤酒大生产中抗氧化能力影响因素的研究

研究了在啤酒大生产过程中的不同阶段抗氧化指标的变化,发现在麦汁制备过程中,糖化和麦汁煮沸是啤酒老化物质大量生成的阶段,同时这两个阶段的还原力有较大幅度的增加。在发酵过程中,酵母可大量还原发酵液中的老化物质,同时提高最终发酵液的还原力。不同的酵母对最终发酵液抗氧化能力的影响是极其显著的。     

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.     

Carrier‐free,continuous primary beer fermentation

Developing a sustainable continuous fermentation reactor is one of the most ambitious tasks in brewing science, but it could bring great benefits regarding volumetric productivity to modern breweries. Immobilized cell technology is often applied to reach the large densities of yeast needed in a continuous fermentation process. However, the financial cost associated with the use of carriers for yeast immobilization is one of the major drawbacks in the technology. This work suggests that yeast flocculation could address biomass immobilization in a gas‐lift reactor for the continuous primary fermentation of beer. Nearly 25 g dry wt L^?1 of yeast was flocculated in the reactor before interruption of the fermentation. Stable sugar consumption and ethanol production (4.5% alcohol by volume) from an 11°P wort was evidenced. The key esters and higher alcohols measured in the young beer met the standards of a finished primary beer fermentation. Copyright © 2014 The Institute of Brewing & Distilling     

牛乳经酵母菌和乳酸菌发酵生产低醇乳酒的研究

用鲜牛乳为主要原料,添加蔗糖和营养素等辅料,经酵母和乳酸菌混合接种发酵,生产出低醇乳酒。通过对2种菌发酵方式的选择、协同性发酵实验、乳酸菌接种量和营养素的添加、发酵条件优化及发酵过程分析和发酵终点确定的研究,结果表明,当蔗糖添加量为10%时,乳酸菌的接种量为1%;牛乳酒生产的最佳配方及工艺条件是牛乳用量30%,营养素添加量70mg/L,酵母接种量8%,温度28℃。经生产性实验,在总发酵时间28h,乳酒产品酒精含量达到2·02%,呈乳白色,状态均匀,泡沫细腻,乳香、酒香和谐一体。     

A review of methods of low alcohol and alcohol-free beer production

The increasing interest of consumers in health and alcohol abuse issues motivates breweries to expand the assortment of products with low alcohol content. The goal of producing beers with low alcohol content can be achieved by two main strategies; namely by gentle removal of alcohol from regular beer and by limited ethanol formation during the beer fermentation. Within these two basic strategies, there are a number of techniques that vary in performance, efficiency and usability. This paper presents an overview and comparison of these techniques and provides an evaluation of sensorial properties of low-alcohol and an alcohol-free beer produced as well as suggests possibilities for their additional improvement.     

固定化酵母细胞在鼠曲草啤酒中的应用

探讨了固定化啤酒酵母在鼠曲草啤酒中的应用，采用正交试验确定了固定化酵母的最佳条件和鼠曲草啤酒的发酵工艺条件。固定化酵母细胞的最佳条件为海藻酸钠浓度为6％，氯化钙浓度为0．5％，固化时间为1h；鼠曲草啤酒的发酵工艺为主发酵前添加3．0％的鼠曲草提取液，发酵时间为8d。     

不同固定化酵母载体对啤酒风味成分影响研究

采用气相色谱分析法,主要考察了山毛榉木片、多孔陶瓷和海藻酸钠3种固定化酵母载体对啤酒风味物质成分的影响。结果表明,不同固定化酵母载体对啤酒风味物质成分的形成有较大影响,其中海藻酸钠载体固定化酵母的牢固程度最好,且载体正丙醇、异丁醇和异戊醇含量分别高于成品啤酒9%、8%和12%,啤酒含醇量较高,适于醇厚型啤酒发酵;山毛榉木载体生成的酯类物质较多,载体乙酸异丁酯、乙酸乙酯、乙酸异戊酯和己酸乙酯含量分别高于成品啤酒20.1%、14.3%、12.5%和17.4%,含酯量较高,适于淡爽型啤酒发酵;与另两种载体相比,多孔陶瓷载体双乙酰含量达到0.14 mg/L,不适合用于啤酒发酵。