硅藻土对啤酒中铁离子含量及啤酒质量的影响

目前世界上使用的啤酒助滤剂中，硅藻土占75％～80％。硅藻土中含有可溶性铁，过滤时进入啤酒，铁离子含量过高，对啤酒质量有不利影响。如：易引起铁蛋白混浊、引发啤酒的喷涌病、带给啤酒金属腥味等等。本实验的目的在于，通过检测不同品牌硅藻土的可溶性铁含量，处理后滤发酵液中铁离子含量，结合TBA实验，来评估不同品牌硅藻土对啤酒中铁离子含量及啤酒质量的影响。     

铁含量分析查找啤酒风味缺陷

铁离子含量超标是导致啤酒铁腥味的主要原因，当啤酒中Fe^2 含量超过0．1mg／L时，就明显有铁腥味。而当酿造水中Fe^2 含量高时，Fe^2 能与麦汁中的单宁发生氧化反应，使色泽加深，经过高温煮沸，加速多酚氧化聚合和啤酒老化。啤酒中铁离子含量的检测是一个不容忽视的问题。本文通过啤酒口感品评，对铁离子引起的啤酒风味缺陷进行分析，查找污染源。     

浅析硅藻土中铁的危害、测定与控制

啤酒过滤用的硅藻土是天然硅藻矿石经锻烧、分级而成,但天然硅藻矿石中含有大量的有机物、砂石、粘土、可溶性碳酸盐和铁等杂质。因此,硅藻土中总有一定量的铁离子,由于啤酒为酸性溶液,当啤酒经过硅藻土过滤时,硅藻土中所含的铁离子便溶入啤酒中。目前,国外啤酒过滤用的硅藻土中铁离子含量已控制在16—48毫克/公斤,使用时再经特殊处理可降至1.4—5.8毫克/公斤;我国啤酒过滤用硅藻土中铁离子含量参差不齐,条件好的企业可控制在50毫克/公斤以下,条件差的企业有时     

石墨炉原子吸收法测定啤酒中的铁

优质啤酒中铁离子的含量应低于0.1mg/L。啤酒中铁离子含量高对啤酒质量的影响是不言而语的。首先,有资料表明啤酒中含 Fe~(2+)>0.4mg/L,即具有明显的金属腥味,而且会导致啤酒泡沫不洁白。另外,铁离子在啤酒中起着氧化接触剂的作用,会促进啤酒的氧化浑浊,进而导致啤酒的口味败坏。近年来国内啤酒行业对啤酒风味稳定性越来越重视。因此测定啤酒中铁离子的含量就显得尤为重要了。目前国内标准中测定铁离子用的是火焰原子化法,但是使用该法在仪器灵敏度足够的情况下最低才能检出0.05mg/L 的铁。而目前许多企业都需将啤酒中的铁含量控制在0.1mg/L 以下,因此使用灵敏度更高的无火焰技术才能满足测定要求。本文研究的就是使用石墨炉原子化法来测定啤酒中的铁离子含量。     

重金属离子对啤酒风味稳定性的影响

本研究主要阐明了啤酒发酵过程中铁和铜离子对啤酒风味稳定性的重要影响。一定浓度的锰离子对啤酒风味稳定性也有一定程度的影响。但与铜和铁离子相比,麦汁或者啤酒中的锰离子浓度在酿造过程中没有改变,另外,锰离子显示出与铁和铜离子相似的有促进自由基反应的作用。啤酒中较高浓度的锰离子显示出特别强的氧化特性。研究结果表明：除了已知的铜和铁离子外,其它金属离子也影响啤酒的风味稳定性。不同的是,进入产品中的锰离子不是来自于容器和管道材料,而是来自于酿造谷物中。这个研究结果可以作为挑选啤酒谷物原料的参考。     

啤酒酿造过程中铁离子的来源，变化及其对啤酒质量的影响

研究了啤酒酿造水、原料、添加剂及助剂中的铁含量和铁离子在啤酒酿造过程中的变化规律。原辅料及添加剂中均含有不同浓度的铁,硅藻土含铁量最高,大米最低。麦汁中铁离子浓度均值在0．29mg／L,发酵过程中部分被酵母吸收,大部分随沉淀物排出罐外。成品酒中的铁离子会促进啤酒羰基类化合物的生成从而影响啤酒风味质量,游离态铁离子会使啤酒货架期前期浊度值升高,而对啤酒色度无显著影响。     

啤酒中铁离子含量的控制

啤酒酿造过程中铁离子（可溶性铁）对麦汁的组成，发酵性能和成品啤酒质量有不同程度的影响。糖化过程中铁离子含量较高，会抑制糖化的进行，加深麦汁色度；发酵阶段铁离子含量过高影响酵母的生长和发酵；清酒灌装以后如果铁离子含量过高，会加速氧化作用。优质成品啤酒中铁离子含量应〈0．10ppm，当铁离子含量〉0．20ppm时，会对成品啤酒产生不同程度的负面影响，当铁离子含量〉0．40ppm时，就有明显的金属腥味和氧化味。[第一段]     

硅藻土过滤阶段影响啤酒抗氧化力的因素与控制

文中结合DPPH和TBA两种分析方法,阐述了硅藻土消耗量、铁离子含量、单宁添加量及啤酒pH值等因素对过滤后啤酒抗氧化力的影响。结果表明,溶入啤酒中铁离子增加,pH值低等会降低啤酒DPPH自由基清除率,即降低了啤酒抗氧化力。     

关于淀粉中铁离子含量的检测及注意点

目前各啤酒厂生产中,淀粉的使用比例一般为40％-50％。淀粉中铁离子含量会影响麦汁及啤酒中的铁含量,严重影响啤酒感官质量。因此,淀粉中的铁含量应是原料的一项重要检测项目。     

联合使用柠檬酸和菲汀降低白酒中铁离子的试验

利用柠酸和菲汀中的有效成分植酸盐，与白酒的二价铁离子、三价铁离子反应，生成分子较大的物质而除去铁离子。通过试验，白酒中铁离子含量可降到５ｐｐｍ以下，起到了了除铁的作用。     

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     

新型添加剂Brewbrite在麦汁制造中的应用

对Brewbrite在麦汁中的应用进行了初步研究．通过麦汁外观和其他指标的分析。结果表明，在麦汁煮沸结束前10min添加Brewbrite 30mg／L，可以有效地澄清麦汁，降低麦汁中的可凝固性氮含量。与卡拉胶、单宁、HD-003，DHG，PVPP等添加剂相比，Brewbrite可降低麦汁和啤酒中的总多酚含量、可凝固性氮含量、麦汁色度、麦汁浊度等，减少高分子氮的比例，有助于提高啤酒的非生物稳定性。（孙悟）     

麦汁煮沸工艺对凝固氮含量的影响

延长煮沸时间和增加煮沸温度可降低麦芽汁凝固氮含量，但会增加麦汁色度；单宁的理想添加浓度为60mg／kg；添加复合硅胶可吸附沉淀部分蛋白质颗粒，降低啤酒色度，提高啤酒非生物稳定性。     

国产(吉隆)单宁在高浓啤酒酿造中的应用

在高浓啤酒酿造中加入国产（吉隆）单宁，最佳使用量为30mg／L。可有效吸附麦汁中高分子敏感蛋白质、啤酒中的杂质、金属离子和促进啤酒中不溶性蛋白质沉淀，加速啤酒中悬浮物沉降，提高啤酒的非生物稳定性和风味稳定性。（孙悟）     

A study of beer bitterness loss during the various stages of the Romanian beer production process

Beer is one of the oldest known alcoholic beverages produced by a yeast fermentation of a cereal extract that was germinated in water beforehand. The bitter taste of beer comes from the group of substances introduced during wort boiling, which are the extracted components of hops. The aim of this study was to determine some characteristics of beer (original extract, alcohol content, colour, pH, total acidity, carbon dioxide and bitterness values) during the three stages of the beer production process in a typical Romanian brewery. Measurements were carried out on 60 samples of beers, 10 measurements for each step of the process examining wort, unfiltered fermented beer and bottled beer (final product) from two different types of beer (light and dark). Statistical process control of the beer was performed. Losses in the bitterness units during the production process were between 24.7 and 41.54%, reported in terms of final product. Copyright © 2013 The Institute of Brewing & Distilling     

CHILL PROOFING BY A STRAIN OF SACCHAROMYCES CEREVISIAE SECRETING PROTEOLYTIC ENZYMES

The attempted exploitation of a strain of yeast with extracellular protease activity in the fermentation of brewers' wort is described. S. cerevisiae strain YS01 was previously shown to secrete proteases with activity against a variety of substrates. It is shown here that these included some of the tannin precipitable proteins involved in the formation of chill haze in beer and consequently, more stable beers resulted from incubation with added YS01 cell-free culture supernatants. The proteases were also produced in an active form at low levels during fermentation of brewers' wort using established commercial conditions. Concomitantly, a marginally more stable beer resulted. Respiratory deficient, auxotrophic rare-mating was used to transfer the extracellular proteolytic characteristic (epr1.1) to a commercial ale yeast. Segregants of the recombinants obtained showed great instability in protease secretion and were unsuitable for brewing purposes. The potential advantages and drawbacks to this approach are discussed.     

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.     

THE INFLUENCE OF FREE ALPHA-AMINO NITROGEN IN SORGHUM BEER FERMENTATIONS

The interactions of wort free α-amino nitrogen (FAN) and sugar in sorghum beer fermentations were quantified and a simple equation derived. This equation describes the wort FAN demand as a function of the sugar concentration necessary to produce a fully fermented beer within 48 hours. The influence of wort FAN on sorghum beer fermentations had not been quantified so research was undertaken to define sorghum beer yeasts' requirement for wort FAN and the interactions that occur between wort FAN and sugar. Laboratory, sorghum malt and adjunct, worts mashed to cover a wide range of FAN and wort sugar concentrations, were fermented and analysed. The initial wort FAN affects the ethanol production rate, FAN uptake and sugar utilisation rates.     

无酒精啤酒的研究

<正> 无酒精啤酒是一种酒精度低于1 w/w％的饮料,它具有啤酒的色、香、味。因其酒精度低特别适于司机、运动员、孕妇、儿童及老年人饮用。无酒精啤酒的生产方法已有许多,但各自又存在着一定的问题,本论文的目在: 1.选出控制或除去酒精的有效方法。 2.以气相色谱法测定风味物质,对产品的风味进行改善。     

啤酒中钙的分析研究

从原理上分析钙离子在啤酒生产中的主要用途,阐述其重要性。利用粗蛋白分解液,采用络合滴定准确、快速测定啤酒及麦汁中钙离子含量。