啤酒讲座(八) 第五讲 麦汁的处理

麦汁的处理包括麦汁过滤、麦汁煮沸、添加酒花、麦汁热凝固物的处理、麦汁冷却、麦汁冷凝固物的处理以及麦汁处理过程中的副产物等。一麦汁过滤1.麦汁过滤的目的糖化工程结束后,应该及时把糖化已经溶出的糖液和没有溶解的麦皮、蛋白质凝固物和原料中的杂质分离出来。被分离出来的糖液称为麦汁,加水洗涤出来的糖液称为洗涤麦汁,遗留在过滤设备中的杂质称为麦糟。麦汁和麦糟的分离时间要求越短越有利于麦汁的质量,麦糟浸泡时间长了,麦皮中的色素被浸出,会给麦汁带来不良的苦涩味和麦皮味。把麦汁和麦糟分开的方法称为麦汁过滤。     

麦汁压滤机在啤酒生产中的应用

介绍了麦汁压滤机在啤酒规模化生产中的应用概况及使用注意事项.实践表明,使用麦汁过滤机来处理麦汁,可克服传统工艺使用过滤槽过滤麦汁的弊端,又能很好地满足麦汁过滤的基本要求,该方法过滤麦汁效率高,麦汁质量好,经济效益明显.     

啤酒糖化过滤槽改造带来的效益

糖化过程麦汁过滤质量 (麦汁澄清度、麦汁过滤速率、麦汁组份 )直接影响麦汁的组成和发酵。由于本公司原过滤槽设计不甚合理 ,出现麦汁回流时间长 ,麦汁中混有麦皮 ,过滤速度慢 ,谷皮成份溶出等现象。1　原过滤槽设计存在的问题1 1　过滤槽筛板空隙较大而且不平 ,可漏过麦皮和细渣 ,过滤槽表面分布力排布 ,造成糟层紧密 ,过滤阻力增大 ,过滤速度减慢 ;1 2　耕刀高度固定 ,不能调节 ,没有充分定位 ,容易破坏糟层 ,头道麦汁有破碎糟带入 ,使细渣和麦皮进入麦汁 ,麦汁虽清亮但仍有碎裂粉带入麦汁 ;1 3　过滤周期达 3小时 ,接触麦汁时间长 ,造成…     

酿造过程对贮藏啤酒中含氮化合物的影响

本文分析了工业生产全麦芽麦汁和玉米辅料麦汁的含氮化合物,以及不同分离技术[麦汁过滤机(Meura 2001)和过滤槽(Steinecker FVAS 26)]的影响.数据表明,(1)与全麦芽麦汁相比,玉米辅料麦汁含较低的总氮化合物;(2)全麦芽麦汁和辅料麦汁的可同化氮均占总氮的20%～24%;(3)与辅料麦汁相比,全麦芽麦汁游离氨基氮几乎是其两倍;(4)脯氨酸和天冬酰胺是两麦汁中最丰富的氨基酸;(5)麦汁发酵过程中铵消失,含氮量降低.此外,对于全麦芽麦汁而言,利用过滤槽,总氮减少80%,利用过滤机,总氮减少25%;对于辅料麦汁而言,利用过滤槽,总氮减少87%,而利用过滤机,总氮减少29%.麦汁过滤后,可同化氮含量足够用于有效发酵,但经过过滤槽分离之后,可同化氮到达到一个值,该值可能影响全麦芽麦汁和辅料麦汁的正常发酵过程.因此,在使用过滤槽时,我们必须控制减少其对含氮化合物的影响,或利用麦汁氮补充来克服发酵中止和缓慢发酵.     

影响麦汁过滤的主要因素及控制

麦汁过滤是糖化生产的重要步骤,关系到麦汁收得率,清亮透明的麦汁可以避免成品酒出现苦涩味,控制好麦汁过滤操作可以提高麦汁新鲜度,提升成品酒口感质量。本文从工艺、设备、操作等方面来阐述如何提高麦汁过滤质量。     

麦汁澄清度对啤酒质量的影响

1.麦汁澄清与凝固物的析出在啤酒酿造中,煮沸后的麦汁在进入发酵罐前,需进行一系列处理,如麦汁冷却,通氧,冷、热凝固物的析出、分离等。最终定型麦汁的质量,除了要求麦汁组分合理外,对于冷、热凝固物应尽可能的分离,使处理后的麦汁清亮、透明。决定麦汁澄清的关键在于凝固物的分离程度。提高麦汁澄清度,可有效     

浅谈平衡罐装置在麦汁过滤过程中的应用

麦汁过滤在啤酒生产过程中是一个非常重要的工艺环节 ,其目的是在糖化工序结束后 ,在最短时间内将糖化醪中从原料溶出的物质与不溶性的麦糟分离 ,以得到澄清的麦汁 ,并获得良好的浸出物收得率。麦汁过滤效果的好坏 ,直接影响到后期麦汁发酵及清酒的过滤和啤酒的泡沫、风味 ,最终影响啤酒的质量。如何在麦汁过滤过程中得到澄清的麦汁 ,其方法很多 ,现就我厂近期采用的平衡罐原理在麦汁过滤中的应用作如下的总结。1　原理把过滤槽底部的各同心环管的麦汁最后集中在一总管内 ,然后流经至麦汁平衡罐 ,由平衡罐流出。利用泵打入麦汁暂存槽或麦汁…     

糖化工艺对啤酒麦汁色度的影响研究

麦汁为啤酒的主要原料,麦汁的制备决定了啤酒的种类和质量,并直接影响到啤酒生产工艺与成品质量,因此在啤酒生产过程中需要不断优化麦汁制备工艺,形成优良的麦汁色度。麦汁的制备工艺主要包括麦芽制备、麦芽粉碎、糖化、麦汁煮沸沉淀、麦汁过滤与主发酵等步骤,其中糖化工艺会对啤酒麦汁的色度与品质造成影响。因此,需控制好麦芽质量及其粉碎度、糖化温度、淀粉酶pH值、糖化醪浓度等因素,并进一步优化糖化工艺参数,为呈现更好的啤酒麦汁色度奠定坚实的基础。基于此,本文研究糖化工艺对啤酒麦汁色度的影响,并提出啤酒麦汁制备中糖化工艺的优化措施,以提高啤酒麦汁的色度,促进啤酒酿造工艺的优化,推动啤酒行业的高质量发展。     

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）     

回旋沉淀前麦汁预冷却实验

为进一步降低麦汁热负荷,提高产品新鲜度和麦汁澄清度,我们在麦汁回旋沉淀前进行了预冷却实验。其目的是提高回旋沉淀效果和麦汁澄清度。有两种方法供大家参考:第一种方法:在麦汁煮沸锅至回旋沉淀槽管路外加一组盘管,通人酿造水对麦汁进行预冷却,可使以后的麦汁冷却时间<55min,冷媒为2～3℃冰水,出水温度70℃,麦汁温度7～8℃;板式冷却器易于CIP清洗。缺点是麦汁实际冷却效果检测困难。     

卡拉胶在啤酒酿造中的应用

主要论述麦汁澄清剂———卡拉胶能够加快麦汁中蛋白质沉淀,特别是除去冷浊蛋白质十分有效,大大改善麦汁的浊度,从而提高啤酒的非生物稳定性。     

麦芽根的综合利用研究进展

主要介绍了国内外对于麦芽根综合利用的研究进展 ,对麦芽根中的蛋白质、酶及其它成分的各种利用作了详细介绍。麦芽根不仅可以直接用于微生物培养 ,风味物和调味品的生产 ,也可以制成蛋白制品、酶制品以作进一步应用 ,其综合利用前景非常好。     

不同蛋白质溶解度的小麦芽蛋白质组成及麦芽质量分析

为了研究小麦芽蛋白质溶解度与蛋白质组分及麦芽指标间的相关性,通过控制不同的浸麦度和发芽时间,制备了蛋白质溶解度分别为31.4％、33.1％、37.0％、37.6％、39.5％、40.9％、45.5％和54.2％的8种小麦芽,分析了小麦芽蛋白质组分、降解酶及麦芽基本指标.结果表明:随着小麦芽库值的增加,水溶性蛋白质含量成线性增加,醇溶性和碱溶性蛋白质呈现直线下降.小麦芽内肽酶活力与水溶性蛋白质含量、水分及浸出物呈现显著正相关(r分别为0.732、0.792和0.727),与醇溶性蛋白质含量呈现显著负相关(r=-0.734).因此小麦芽内肽酶活力的提高将有助于小麦芽浸出物的增加.小麦芽库值与水分、色度、浸出物、FAN、酸度均存在极显著正相关性(r=0.885、r=0.971、r=0.880、r=0.915和r=0.964);与浊度存在显著正相关(r=0.714);与有效酸度存在极显著负相关(r=-0.921).所以提高蛋白质溶解度小麦芽浸出物、浊度、FAN、酸度、色度等指标都会提高.比较8种小麦芽指标,蛋白质溶解度为39.5％时小麦芽指标较好.此时,浸出物为82.0％,FAN 166 mg/100 mg,糖化力为496 WK,黏度为1.61 cP,糖化时间为6 min.     

Effects of seeding rate, nitrogen rate and cultivar on barley malt quality

BACKGROUND: Crop management tools have been shown to affect barley kernel size and grain protein content, but the direct effect on malt quality is not well understood. The present study investigated the effect of seeding rate, nitrogen fertilisation and cultivar on malt quality. RESULTS: Higher seeding rates produced barley with less grain protein and smaller, more uniformly sized kernels. The small, uniformly sized kernels modified more completely, leading to malt with higher extract and lower wort β‐glucan than malt from low‐seeding‐rate barley. Increasing rates of nitrogen fertilisation caused grain protein levels to increase, which limited endosperm modification and reduced malt extract levels. AC Metcalfe showed better modification and higher malt extract than CDC Copeland, but CDC Copeland had better protein modification at higher fertilisation rates, which resulted in less reduction of malt extract as nitrogen rate increased. CONCLUSION: Higher seeding rates reduced kernel size and grain protein levels without compromising malt extract owing to better endosperm modification of the more uniformly sized kernels. Negative effects of higher nitrogen rates on malt quality can be reduced through development of cultivars with improved ability to modify protein during malting. © 2012 Her Majesty the Queen in Right of Canada     

HIGH PERFORMANCE LIQUID CHROMATOGRAPHY OF BARLEY PROTEINS: RELATIVE QUANTITIES OF HORDEIN FRACTIONS CORRELATE WITH MALT EXTRACT

Several high performance liquid chromatography (HPLC) approaches have been used to study the relationships between amounts of particular groups of grain storage proteins (hordeins) and malt extract, using two sets of barley samples. The areas of several chromatogram peaks varied between samples in a manner that correlated with malt extract. Size-exclusion HPLC of protein aggregates extracted by sonication gave negative correlations of the relative areas of the three largest chromatogram peaks with malt extract in a set of 39 samples of the one variety, but not in a set of samples of 8 varieties grown at 4–5 sites. Under reducing conditions, disulphide-bonded hordeins were quantitatively extracted and the proportion of hordein in the largest peak, comprised of D- and B-hordeins, correlated well with malt extract in both sets of samples. The hordeins sequentially extracted into 50% (v/v) 1-propanol and 50% (v/v) 1-propanol-50 mM dithiothreitol (DTT) were also analysed by reversed-phase HPLC, and could be resolved into several peaks of B-, C- and D- hordeins. Relationships between the amount of certain C- hordeins in the propanol extract, and certain B- hordeins in the propanol-DTT extract and malt extract were seen. As well as providing a better understanding of the relationship between barley grain protein composition and malting quality, these HPLC methods are useful additional methods to enable partial prediction of malt extract using un-malted barley.     

AREAS OF ABSORPTION RELATING TO MALT EXTRACT VALUE IN MODIFIED NEAR INFRA-RED SPECTRA OF BARLEY FLOUR

Determinations of milling energy, nitrogen, acid-soluble beta glucan and malt extract after micromalting, were made on grain samples of twenty nine barley cultivars. In addition the flour from unmalted grains was scanned over the near infra-red spectrum, and the scan data were subjected to a principal components analysis (PC). Predicted malt extract values resulting from an NIR multiple regression equation with PC terms, correlated well (r = 0.934) with the manual extract values. This confirms previous evidence that malt extract value depends largely on constituents in the resting grain, rather than on malt enzymes. An attempt to locate NIR absorptions relating to malting quality was made by restructuring the NIR spectrum of the samples according to the weightings modified by the regression coefficients in the PC regression equation for hot water extract value. The spectrum reconstructed in this way showed a number of absorption peaks and troughs. From comparison with previous NIR scans it was concluded that a strong peak at the wavelength 2100 nm was due to a starch absorption and this together with minor starch overtone peaks correlated positively with malt extract. Troughs at 2180 nm, 1980 nm and 1700 nm indicated a negative association between malt extract and some proteins. There were also wide troughs at 1830 and 2330 nm indicating a negative relationship between malt extract and beta glucan. Other peaks and troughs in the reconstructed spectrum could not readily be assigned to a constituent. A reconstructed protein spectrum consisted of peaks and troughs that agreed with previous assignations for protein absorbancies. A milling energy reconstruction was approximately the inverse of the malt extract spectrum, and an acid-soluble beta glucan reconstruction was relatively featureless and appeared to be due to the effects of particle size variations.     

ENZYMIC PROTEIN HYDROLYSATES FROM MALT SPROUTS

Recent literature on the use of malt sprouts is reviewed. Studies on the hydrolysis of malt sprouts by alkaline protease were carried out to determine the optimal conditions required. Under these conditions an overall 40% solubilisation of the malt sprouts was achieved which incorporated a 65% solubilisation of the total protein content. Amino nitrogen content of the malt sprouts reached 0.8% on hydrolysis. The extract from the hydrolysed malt sprouts contained approximately 40% hydrolysed protein, 40% dextrins and salts. Evaporation of this extract produces a viscous syrup and spray drying produces a hydroscopic powder containing 1.8–2.0% amino nitrogen. The protein part of the hydrolysate extract is balanced with respect to its essential amino acid content and has a low bitter taste. Data from experiments carried out on the effect of the extract on yeast fermentation indicate a significant stimulation and possible applications in the food industry.     

Composite malt with dark-purple rice malt improves the phenolic profile and antioxidant activity of malt extract

This research presents a modification of bioactive compounds of malt extract produced from Riceberry rice malt (RRM)–barley malt composite for malt-based beverage. Malt extract was produced by varying RRM at 20% w/w, 40% w/w, 60% w/w, 80% w/w, and 100% w/w and were analysed for total polyphenol content (TPC), phenolic acids constituent, and antioxidant activity. The 100% RRM extract was rich in TPC relative to 100% w/w barley malt extract. The composite malt extract containing 40% w/w–80% w/w RRM had enough TPC in the filtered malt extract (236–524 mg L⁻¹) and boiled hopped malt extract (216–485 mg L⁻¹) and were directly proportional to the antioxidant activity in the extract. Barley malt fraction in the malt extracts had a positive response on ferulic acid and sinapic acid, whereas RRM inclusion in malt extract increased p-coumaric acid, vanillic acid, rutin, and methyl coumarate concentration. Therefore, the cereal malt composite could provide strong oxidative stability to the malt extract and derived products.     

Mechanisms of Malt Extract Development in Barleys from Different European Regions: II. Effect of Barley Hordein Fractions on Malt Extract Yield

To examine environmental differences between southern and northern European malting barleys, particularly relating to protein and hordein influences on malt extract development, samples of the malting barley cultivar Alexis, from the Nordic countries and from the Iberian Peninsula, were used. Fractionation of hordeins was carried out on barley grams, prior to micromalting and malt analyses, using high performance liquid chromatography (HPLC). Different mechanisms for extract development, in malting barleys from the North and South of Europe, have been demonstrated. Barley protein content determined a significantly greater decrease in malt extract in the Nordic samples, compared with those from the Iberian Peninsula, while apparent final attenuation showed a more pronounced positive association with extract in the South than in the North. B‐hordein was associated with a significanlty greater decrease in malt extract in the Nordic compared to the Mediterranean samples.     

EVALUATION OF BARLEY AND MALT QUALITY USING NEAR-INFRARED REFLECTANCE TECHNIQUES

A scanning near-infrared reflectance spectrophotometer was calibrated for the prediction of barley aleurone colour and malt moisture. The malt moisture was predicted on malt ground for the determination of malt extract (coarse grind) making the method suitable for moisture correction in malt extract estimation. Calibrations for the prediction of malt extract and endosperm modification from barley and malt were also attempted. A correlation (r= 0.851 n = 135) was found between malt hot water extract and the percentage of the endosperm estimated as being modified by microscopy following staining with Calcofluor. Probably because of this influence of modification on malt extract, the use of near-infrared reflectance to predict malt extract was most successful at predicting the malt extract values obtained following micro-malting in the absence of the additives, gibberellic acid and potassium bromate.