麦汁煮沸中相关问题的探讨

麦汁煮沸是啤酒酿造中糖化工段的一项重要的操作过程。该文通过对煮沸热传导原理及几种不同麦汁煮沸设备的介绍,提出了麦汁煮沸控制措施和结垢处理方法,以及使用麦汁煮沸装置时的注意事项。     

Proteome analysis of the wort boiling process

A comprehensive proteome map was constructed of brewers wort. The map consisted of protein identification on two-dimensional gel electrophoresis (2DE) images and identified 63 out of 202 protein spots, which were categorized into 20 protein species. To analyze the modification of protein Z during wort boiling, protein Z spots on 2DE gel of the sweet wort, the boiled wort and the trub were analyzed by matrix-assisted laser desorption ionization time of flight mass spectrometry (MALDI TOF-MS) and then the spectra were compared. The analysis identified several specific signals detected only in the trub, suggesting that specific modification occurred in the precipitated protein Z during wort boiling. The protein Z spot on the 2DE gel of the precipitate was further analyzed by liquid chromatography mass spectrometry/mass spectrometry. The analysis identified low molecular weight fragment (1.3 kDa) derived from wound induced protein (barwin) in the protein Z spot of the trub. These results suggested that protein Z was precipitated by binding with comparatively small size specific fragment(s) derived from sweet wort protein, i.e., barwin during wort boiling. Our results and understandings have application for quality assurance and control in commercial brewing practice, and development of DNA markers for malting barley breeding.     

PERFORMANCE OF A STEAM EDUCTOR IN A PILOT BREWERY

Steam eductors have the potential for reducing the demand for steam during the evaporation of wort by up to 50% with low capital expenditure and without affecting the process of wort boiling or the flavour of beer. The theory describing the operation of eductors is discussed together with sample calculations for the prediction of performance. A small unit was installed on a kettle in the Holyrood pilot brewery to demonstrate the practicality of the principle and to obtain experience in operation. The unit performed in a manner in keeping with theory and had an efficiency of 90%. There is a great likelihood that the economic advantage of steam eductor systems will be very close to theoretical prediction.     

Optimization of the vaporization of flavour components during wort boiling in the brewery by implementing a rectification column

Boiling the wort is an energy‐intensive step during beer production. The central objective of the process is the evaporation of unwanted flavour components, above all the flavour component dimethyl sulphide (DMS). To reduce the required overall evaporation, a recent development involves the insertion of a stripping column into the vapour discharge vent of the wort kettle in which the wort is directed from the kettle against the ascending vapour. The calculation by means of procedural fundamentals and the validation of the process in a large brewery are the subject matter of this article. Process improvement in comparison with conventional boiling systems is documented. Copyright © 2017 The Institute of Brewing & Distilling     

Vitamins in brewing: the impact of wort production on the thiamine and riboflavin vitamer content of boiled sweet wort

Wort production contains a number of processing steps that are aimed at the optimal extraction of nutrients from malt, including vitamins. This research revealed that the different wort production processing steps imposed different influences on the thiamine and riboflavin vitamer content of the final sweet wort. These vitamins play vital roles within yeast metabolism, where they act as enzyme cofactors. As such thiamine vitamers play a crucial role in many decarboxylating enzymes, while riboflavin vitamers play an integral role in energy production and redox maintenance. While mashing releases valuable starch into the liquor, both thiamine and riboflavin are also extracted. The extraction of these vitamins is the greatest at 65°C and is indirectly linked to the amylase activity. When the starches are broken down during mashing, the thiamine and riboflavin vitamers are gradually released into the mash liquor. The boiling and trub removal (whirlpool) processes impose losses in both vitamins owing to the high temperatures exhibited during these stages. While hop pellets were shown to contribute a small proportion of the vitamers studied, the use of kettle finings caused a significant reduction in both thiamine and riboflavin vitamers. Copyright © 2014 The Institute of Brewing & Distilling     

Study on the buffering capacity of wort

The effect of the buffering capacity of wort on a beer fermentation and the contribution of pH, phosphate, amino acids and organic acids to the buffering capacity of wort were studied. The beer pH depended on the buffering capacity of the corresponding wort and an increase in the buffering capacity of the wort could prolong the time of diacetyl conversion. The higher the wort pH was, the larger the wort buffering capacity. Phosphate was not an effective buffer at the pH of wort. Glutamic acid, aspartic acid and histidine gave weak contributions to the buffering capacity of wort, and the total contribution of these three amino acids was <0.1. Organic acids contributed substantially to the buffering capacity of the wort and the total contribution of organic acids to the buffering capacity of the wort was estimated to be about 0.31. The buffering capacity of lactic acid, citric acid, succinic acid, fumaric acid and pyruvic acid was 30, 50, 77, 15 and 9% of that of acetic acid, respectively, at the same mass concentration. Copyright © 2015 The Institute of Brewing & Distilling     

Validation and discussion of the vaporization surface

This article deals with the impact of a vaporization surface in the brewing industry. The vaporization surface is deemed to have a positive impact on the evaporation quality of unwanted flavour components – especially dimethyl sulphide. Based on physico‐procedural considerations and trials, the current article deduces and verifies that an increased vaporization surface does not have an enhancing impact on evaporation quality. Copyright © 2015 The Institute of Brewing & Distilling     

麦汁苦味测定方法的探讨

本文主要针对测定麦汁苦味值时，对麦汁的前处理的方法进行试验探讨。     

麦汁制备中蛋白质水解的研究

采用传统的糖化工艺,研究了复合型蛋白酶、中性蛋白酶和木瓜蛋白酶对麦汁制备中的国产大麦芽和大米蛋白质的水解情况。结果表明:在添加蛋白酶之后,大麦芽和大米蛋白质的分解程度均大幅度提高;对于大米而言,在液化前添加蛋白酶对大米蛋白质进行预水解的糖化工艺,可大幅度的提高麦汁中的α-氨基酸态氮含量,同时具有合理的隆丁区分。通过比较,复合型蛋白酶的作用效果最好,其次是中性蛋白酶,木瓜蛋白酶最差。     

麦汁煮沸节能技术探讨

啤酒生产过程的热能消耗除CIP和热水制备外，主要耗能集中在醪液升温、麦汁升温以及麦汁煮沸等工段。实现麦汁煮沸工段节能降耗的技术措施有：回收煮沸乏汽节能，包括采用乏汽冷凝器回收乏汽和采用乏汽压缩机节能；采用新型煮沸系统节能，可采用Merlin煮沸系统节能，或采用柔和煮沸系统节能，或采用Stromboli煮沸系统节能。     

中性蛋白酶对啤酒酿造中麦汁质量的影响

随着啤酒工业的发展,酶制剂在啤酒酿造中的应用越来越广泛.文中主要对中性蛋白酶在糖化过程的应用及对麦汁的影响进行了研究.研究表明,中性蛋白酶添加量在250mg/(kg麦芽)以下,可以使麦汁中α-氨基酸态氮含量提高25%以上,高于250mg/(kg麦芽)反而不利于酶的作用.添加中性蛋白酶只能在一定程度上降低麦汁浊度和敏感蛋白含量,若要进一步提高麦汁稳定性,需要同时采取相应措施,控制麦汁中多酚物质的含量.     

Vitamins in brewing: presence and influence of thiamine and riboflavin on wort fermentation

Thiamine and riboflavin vitamers are present in a wide range of foods including beer. These vitamers play critical roles in a variety of enzymatic complexes and can promote and maintain metabolism. Currently, the presence and role of these vitamers in the malting and brewing industry have not been widely explored. This research investigated the effects of various fermentation conditions that may lead to the variations in the vitamin content in beer observed by previous researchers. The present research found that during fermentation, the thiamine content of wort is quickly utilized within the first 6 h of a standard fermentation and the uptake of this vitamin is not affected by increases in wort gravity. While no significant changes were observed in extracellular phosphorylated vitamers of thiamine, both free thiamine and thiamine diphosphate accumulated intracellularly during the wort fermentation. Meanwhile extracellular riboflavin vitamers were only poorly utilized during beer fermentations, however flavin mononucleotide rapidly accumulated intracellularly and more so under aerobic conditions. When yeast was exposed to an all‐malt high‐gravity wort, the thiamine or riboflavin utilization was not affected. However, thiamine utilization was reduced in adjunct‐driven high‐gravity worts. Notwithstanding the lowered thiamine uptake under high‐gravity conditions; there were some minor improvements in fermentation performance and yeast viability. The addition of thiamine to an all‐malt wort did appear to enhance yeast viability, both under normal and high‐gravity conditions. Copyright © 2016 The Institute of Brewing & Distilling     

反相高效液相色谱法(RP-HPLC)测定麦汁中的草酸

利用反相高效液相色谱法(RP-HPLC)测定麦汁中的草酸含量。对各种色谱条件进行了研究,最终确定色谱柱Hypersil ODS 4.0×125mm,流动相为0.5%KH2PO4-0.5mmol/L TBA(tetrabutylammonium salt,四丁基铵盐)水溶液,pH2.0,紫外检测波长220nm。试验证明该方法能有效地分离麦汁中的草酸和酒石酸,准确灵敏、回收率高、重复性好,并且操作简便,可应用于啤酒生产中草酸含量的检测。     

A New Validation of Relevant Substances for the Evaluation of Beer Aging Depending on the Employed Boiling System

During the last years changes in aging indicators have been observed, supposedly resulting from modern brewing technology. The Research Brewery Weihenstephan (Forschungsbrauerei Weihenstephan) offers excellent opportunities for comparing different modern wort boiling systems under semi‐industrial conditions. Employing three different boiling systems, nine brews were produced. The resulting worts were compared regarding the most common wort parameters. Furthermore the influence of the different boiling systems on aging indicators in the resulting beers was analyzed using a newly developed mass spectrometry‐based method. The decrease in the total amount of aging indicators in industrial beers over the last years is very likely the result of lower thermal intake in modern brewhouse equipment. The total amount of aging indicators is sufficient to describe the differences in modern boiling systems. In summary, 2‐furfural dominates all other indicators in terms of thermal influence. 2‐Furfuryl ethyl ether can be suggested as good indicator of aging as postulated by Eichhorn, whereas β‐damascenone is questionable as an aging indicator. Supplementary experiments were carried out to investigate the role of the aging indicators as stale flavour components. Because of synergistic effects, many stale flavour compounds act as aroma compounds and not only as indicators.     

麦汁煮沸对啤酒老化前驱物质形成的影响

麦汁煮沸是啤酒生产的一个重要环节,煮沸过程影响着啤酒内味老化前驱物质的形成。避免过高的热负荷、隔氧煮沸、有效去除麦汁固形物等方法,可以减少麦汁中的羰基化合物的含量,从而提高啤酒的风味稳定性。     

糖化工艺对麦汁中游离嘌呤碱基含量的影响

采用优化的反相离子对色谱法,对麦汁中4种嘌呤碱基和3种嘌呤核苷进行检测:7种化合物的平均回收率为95.13%～102.12%,相对标准偏差为0.10%～6.55%。设计正交实验利用SPSS18.0软件分析糖化工艺对麦汁中游离嘌呤碱基含量的影响,结果显示:料水比(A)、糖化温度(B)、蛋白质休止时间(C)和蛋白休止温度(D)均具有显著性影响,主次顺序为B>A>C>D,优化工艺为料水比1:2.5,45℃保温50min,升温至62℃,麦汁中游离嘌呤碱基含量从43.82mg/L提高到61.39mg/L,同时,嘌呤核苷从55.46mg/L降低为29.21mg/L。      

Indirect determination of carbohydrates in wort samples and dietetic products by capillary electrophoresis

The first total separation by electrophoresis of five carbohydrates, sucrose, maltotriose, maltose, glucose and fructose, is described. The basic technique requires 1‐naphthylacetic acid as background electrolyte at pH 12.5, indirect UV detection at 222 nm, with a capillary of 75 µm × 120 cm and a voltage of 25 kV. Linear calibration curves from 50 to 400 mg l^?1 with a good correlation coefficient were obtained. The method has been used to determine carbohydrates during the brewing process of a non‐alcoholic beer and also to analyse the carbohydrate content of dietetic fruit juices and chocolate. Copyright © 2004 Society of Chemical Industry     

麦汁缓冲性能对啤酒酵母高级醇生成量的影响

在麦汁主要成分给定的情况下，水质、外加酸以及麦汁煮沸时间是影响麦汁缓冲容量的重要因素，缓冲容量愈大，高级醇含量愈高。结果表明：pH5．0的酸水糖化效果较好；较大缓冲容量的水质有利于麦芽的糖化；盐酸、磷酸和乳酸的使用能提高麦汁的缓冲容量；充分的煮沸可使其缓冲容量降低30％以上；麦汁的缓冲容量对啤酒中高级醇浓度有较大的影响，可以通过控制麦汁的缓冲容量来实现对发酵过程pH的控制。     

啤酒和麦汁中反-2-壬烯醛前体物质检测方法的优化及应用

对固相微萃取-气质联用法（SPME-GC-MS）测定啤酒或麦汁反-2-壬烯醛前体物质的方法进行了优化,分别研究了前处理保护气种类、流速、通气时间、反应体系pH值和加热环境对反-2-壬烯醛前体物质转化效果的影响。结果表明,选择保护气为氮气、气体流速为2 mL/s,通气时间为3 min最为合适;反应体系pH值在4.5时转化率最高,加热环境油浴效果要好于水浴。通过验证试验得出上述各条件优化后,转化率提高了19.49%,说明该方法较传统方法的转化率大大提高,可用于啤酒生产中对啤酒老化潜在隐患的预判。     

即墨黄酒煮糜工艺对挥发性物质的影响

采用溶剂辅助风味蒸发(solvent assisted flavor evaporation,SAFE)和顶空固相微萃取法(headspace solid-phase microextraction arrow,HS-SPME-ARROW)结合全二维气相色谱-飞行时间质谱技术(comprehensive two di-...