Study on the Membrane Filtration of Mash with Particular Respect to the Quality of Wort and Beer

The quality of a membrane filtered wort, and the beer from it, is different from that produced with a lauter tun or mash filter. A membrane is capable of producing a clear wort in terms of turbidity while solid contents, in particular larger molecular substances, are retained. The selectivity of separation is not directly set by the membrane's pore size but rather by the formation of the fouling layer. Thus an interaction between technical filtration parameters and selectivity determines the quality of the resulting wort and beer. The filterability of a beer produced with a membrane filter system for lautering was considerably better when a poorly modified malt was used and foam stability was worse when a normally modified malt was used. For all other properties examined in the beers, no significant differences between lauter tun and membrane filtration including sensory characteristics were observed.     

The Gel Filtration Chromatographic‐Profiles of Proteins and Peptides of Wort and Beer: Effects of Processing — Malting,Mashing, Kettle Boiling,Fermentation and Filtering

Barley and malt proteins, of infusion (IoB) and decoction (EBC) mashing worts as well as commercial wort and beer, obtained from the Castlemaine Perkins brewery, Brisbane, were gel filtered, with or without further treatments. A general, similar pattern of protein and peptide profiles emerged from barley malt and beer. This confirmed the widely assumed fact that beer proteins descend from barley, some transformed and others perhaps mostly unchanged by processing. In the gel‐filtrate profiles, a maximum of 8 or 9 fractions were discerned. These fractions were collected and quantified for protein contents and amino acid compositions. The first four fractions contained the proteins and polypeptides of molecular weight higher than 14,000. Consequently, the remaining fractions contain the smaller peptides (<14,000), that were completely removed by dialysis. The effects of processing on proteins and peptides varied contingent upon the type of processing step considered and the pre‐chromatographic treatment. Malting was the most effective process remarkably increasing the soluble protein contents, especially the smaller peptide fractions and the colour development. This is the first report, as far as we are aware of, on the gel filtration profiles of wort and beer low molecular weight peptides including those of barley wort. The importance of the smaller peptides in foam formation and retention cannot be overemphasised. The amino acid composition of the fractions revealed much more diversity than was observed in the comparison of the profiles. Proline content of fraction 1 resembled that of barley soluble proteins while fractions F2, F3 and F4 that of glutelin and only fraction 8 that of hordein. The latter, suggests that hordeins or, at least the peptide products rich in proline, are likely to be completely digested to amino acids, during malting.     

啤酒过滤性能探讨

影响啤酒过滤的主要因素有过滤前酵母细胞浓度、酒液粘度、固形物含量、稳定剂等;对β-葡聚糖、α-葡聚糖、酵母、颗粒物对啤酒过滤性的影响进行研究分析。改善啤酒过滤性的措施主要有降低麦汁和啤酒中β-葡萄糖的含量,降低过滤前酒液中的酵母细胞数,控制添加剂的添加,添加过滤助剂。(孙悟)     

CAMBRIDGE PRIZE LECTURE INDUSTRIAL SCALE RESEARCH INTO MALTING AND BREWING PROBLEMS*

A series of investigations into production processes is described. The interaction of grain and its environment during commercial barley steeping and germination has been examined. Deficiencies which may be induced by anaerobic conditions in steeping appear to be eliminated during germination. Conversely, malt quality may be affected by excessive steep aeration. In a study of commercial brewery fermentations the importance of wort production procedures in allowing an adequate supply of unsaturated fatty acids, essential for satisfactory attenuation, has been demonstrated. Differences in fermentation behaviour cannot be fully explained by the observed yeast sterol contents. Yeast glycogen does not appear to limit fermentation performance. The application of cross-flow membrane filtration (ultra- and microporous filtration) to the recovery of beer from conditioning tank residues has been examined. The pilot-scale production of high quality permeates, and the successful blending of permeate into finished beer, have been demonstrated. The economic advantages of the ultrafiltration process are assessed briefly.     

Comparison of beer quality attributes between beers brewed with 100% barley malt and 100% barley raw material

BACKGROUND: Brewing with 100% barley using the Ondea^® Pro exogenous brewing enzyme product was compared to brewing with 100% barley. The use of barley, rather than malt, in the brewing process and the consequences for selected beer quality attributes (foam formation, colloidal stability and filterability, sensory differences, protein content and composition) was considered. RESULTS: The quality attributes of barley, malt, kettle‐full‐wort, cold wort, unfiltered beer and filtered beer were assessed. A particular focus was given to monitoring changes in the barley protein composition during the brewing process and how the exogenous OndeaPro^® enzymes influenced wort protein composition. All analyses were based on standard brewing methods described in ASBC, EBC or MEBAK. To monitor the protein changes two‐dimensional polyacrylamide gel electrophoresis was used. CONCLUSION: It was shown that by brewing beer with 100% barley and an appropriate addition of exogenous Ondea^® Pro enzymes it was possible to efficiently brew beer of a satisfactory quality. The production of beers brewed with 100% barley resulted in good process efficiency (lautering and filtration) and to a final product whose sensory quality was described as light, with little body and mouthfeel, very good foam stability and similar organoleptic qualities compared to conventional malt beer. In spite of the sensory evaluation differences could still be seen in protein content and composition. Copyright © 2011 Society of Chemical Industry     

Effect of Carbonyl Sulphide (COS), Ethyl Formate (EF) and Carbon Disulphide (CS2) on the Malting Quality of Barley and the Flavour Profile of Beer

New fumigants are needed to control grain insects because methyl bromide is being phased out as an ozone‐depleting substance under the Montreal Protocol and because resistance to phosphine is increasing. Alternative fumigants also provide one strategy to manage resistance. To assess the effect of candidate fumigants on barley quality, malting and brewing trials were conducted with malting barley (Schooner), 9.4% moisture content, fumigated with carbonyl sulphide (COS), ethyl formate (EF) and carbon disulphide (CS₂) at concentrations of 20, 90 and 36 mg/L respectively for 7 days at 20°C in riveted steel silos containing 33 t of barley. The appropriate industry body, the Malting and Brewing Industry Barley Technical Committee (MBIBTC) set the quality parameters to be evaluated and allocated work to the appropriate quality laboratories. Germination of fumigated barley was not affected by the fumigants. Residues of COS, EF and CS₂ in outloading barley samples were 0.085 ± 0.0052, 0.4 ± 0.1 and 2.22 ± 0.07 mg/kg respectively, which were below the experimental permits of maximum residue levels (MRL). Residues of COS, EF and CS₂ in malt, wort and beer were indistinguishable from those in unfumigated (or non‐fumigated) barley. Ethyl formate and CS₂ affected wort in increasing the apparent attenuation limit (AAL) and CS₂ affected barley colour. Sulphur volatiles in the trial beer made from EF and CS₂ (unlike COS) fumigated barley decreased significantly. Beer from COS, EF and CS₂ fumigated barley had a somewhat higher 24‐hour chill haze level (0.62–0.84) than beer from the untreated barley (0.53). The total alcohols and isoamyl acetate increased in beer made from EF fumigated barley. Carbonyl sulphide, EF and CS₂, however, had no effect on beer flavour or quality.     

制麦和酿造过程中脱氧雪腐镰刀菌烯醇的初步研究

2008年江苏某农场的赤霉病感染相对严重的KA-4B大麦中,脱氧雪腐镰刀茵烯醇（DON）的含量为1．91mg/kg。以此大麦为原料,实验室规模下进行制麦和酿造实验,结果表明,浸麦可以洗去大麦本身含有的绝大部分DON;而大麦内部没有被洗掉的镰孢霉属真菌孢子在发芽阶段重新萌发、生长代谢,形成并积累大量的DON;焙燥阶段不能破坏DON,成品麦芽和麦根中DON的含量分别是原大麦中DON含量的51％和89％。麦芽中的DON可以经过糖化和发酵过程流入到啤酒中,啤酒中DON的总含量是麦芽粉中DON总量的86％。而同一年份相邻农场的基本未感染赤霉病的KA-4B大麦中,DON含量低于0．1mg/kg,绿麦芽和麦根中均检测到低于0．1mg／kg的DON,而成品麦芽、麦汁和啤酒中均未检测到DON。制麦及酿造实验表明,与基本未感染赤霉病的KA-4B大麦相比,赤霉病感染程度严重的KA-4B大麦微生物污染严重,DON含量相对高,大麦品质较差,发芽率较低,麦芽浸出率低,所制得麦汁的过滤速度快,麦汁和啤酒的色度均较高。     

100%大麦啤酒酿造过程中老化Strecker醛的研究

分别采用上面发酵工艺与下面发酵工艺进行100%大麦啤酒及100%麦芽啤酒的酿制,并对其麦汁的氨基酸含量、老化Strecker醛、自由基以及新鲜啤酒中老化Strecker醛的含量等进行了对比分析。研究发现,就麦汁而言,100%大麦麦汁中老化Strecker醛的含量都明显低于100%麦芽麦汁;同样的麦汁,上面发酵方式还原Strecker醛的能力明显优于下面发酵方式。就啤酒而言,经酵母还原后,新鲜啤酒中的老化Strecker醛含量较麦汁含量低,且100%大麦啤酒中老化Strecker醛的含量低于100%麦芽啤酒中的含量。100%麦芽麦汁的自由基含量是100%大麦麦汁的近3倍。这都预示着100%大麦啤酒的风味稳定性（新鲜度）明显好于100%麦芽啤酒。     

Corn grist adjunct – application and influence on the brewing process and beer quality

In the brewing industry, barley malt is often partially replaced with adjuncts (unmalted barley, wheat, rice, sorghum and corn in different forms). It is crucial, however, to preserve constant quality in the beer to meet the expectations of consumers. In this work, how the addition of corn grist (10 and 20%) influences the quality of wort and beer was examined. The following parameters were analysed: wort colour, dimethyl sulphide (DMS) and protein content, non‐fermentable extract, extract drop during fermentation, alcohol content and the attenuation level of the beer, together with filtration performance. The samples (all‐malt, and adjunct at 10 and 20% corn grist) were industrial worts and the beers produced in a commercial brewery (3000 hL fermentation tanks). The application of 10 and 20% corn grist had an effect on the wort colour, making it slightly lighter (11.1 and 10.5°EBC, respectively) than the reference barley malt wort (12.2°EBC). The free amino nitrogen level, DMS and non‐fermentable extract were significantly lower in the worts produced with the adjunct; the alcohol content and attenuation levels were higher in the beers produced with adjunct. The use of corn grist, at the level of up to 20% of total load, appears to affect some of the technological aspects of wort and beer production, but it does not significantly influence the final product characteristics. Copyright © 2014 The Institute of Brewing & Distilling     

Malted and unmalted oats in brewing

Using oats as a raw material in brewing has recently become the focus of increased interest. This is due to research findings that have shown that oats can be consumed safely by coeliac sufferers. It is also a response to consumer demand for products with novel sensory properties. In this study, beer was produced entirely from oat malt, from barley malt and from oat and barley malts mixed with various quantities of unmalted oats. Compared with barley wort, wort made from malted oats provided a lower extract content and had a higher protein content, but a lower free amino nitrogen content (FAN). The oat wort also showed increased viscosity and haze. The addition of unmalted oats during wort production produced significant changes in the physico‐chemical parameters of both oat and barley worts and beers. Unmalted oats caused an increase in wort viscosity and haze, and a reduction in total soluble nitrogen and FAN. Unmalted oats also contributed to lowering the concentration of higher alcohols and esters. Beer made from 100% oat and barley malts exhibited a similar alcohol content. The use of an oat adjunct in both cases resulted in a lower ethanol content. The introduction of enzyme preparations during the production of wort with oat adjunct had many benefits: increased extract content and FAN; a higher volume of wort; and a lower viscosity that led to faster wort filtration. This research suggests that the use of enzymes is necessary to make production using a high proportion of oats in the grist profitable. Copyright © 2014 The Institute of Brewing & Distilling     

西瓜啤酒制作工艺的研究

以西瓜汁和大麦芽为主要原料,采用啤酒独特的低温发酵工艺酿制西瓜啤酒。通过单因素试验和响应面分析试验,以感官评分为评价标准,结合理化指标研究了西瓜汁添加量、西瓜汁添加时间和原麦汁浓度对西瓜啤酒品质的影响。确定了西瓜啤酒的最佳发酵工艺条件为：西瓜汁添加量14.0%,在发酵的第4.5天添加西瓜汁,原麦汁浓度11.2°P。在此条件下,进行了400 L发酵罐的验证试验,获得了一种具有西瓜清爽口感和啤酒典型口感的西瓜果味啤酒。     

The influence of unmalted barley on the oxidative stability of wort and beer

The aim of this study was to investigate the influences of unmalted barley on the brewing process and the quality of the resulting beer‐like beverages, with the main focus on the oxidative stability, using traditional beer analyses, GC‐MS for the determination of aging compounds and electron paramagnetic resonance spectroscopy to determine free radical activity. For the investigation, brews with different barley proportions and 75% barley brews with a colour malt addition, to compensate for a lower colour using barley, were produced. In general, it can be said that beers with a proportion of up to 50% barley achieved a comparable or higher extract yield and final attenuation owing to the combined effectiveness of the malt and microbial enzymes. Although all analytical values were within the normal range according to Methodensammlung der Mitteleuropäischen Brautechnischen Analysenkommission (MEBAK), a slight decrease in total polyphenols and free amino nitrogen content was observed. Also in response to higher barley portions, an increase of higher molecular weight proteins and β‐glucan was detected. Barley is not exposed to heat and oxidative stress in the malting plant, which explains the lower values of the thiobarbituric acid index and colour as an indicator of Maillard reaction products in the resulting wort and beer. Additionally, the results demonstrate a slower increase of aging compounds during beer storage with increasing barley proportions. Furthermore, it was observed that higher barley proportions led to a better oxidative stability indicated by a lower radical generation (T₄₅₀‐value) in wort and an increasing beverage antioxidant index/endogenous antioxidative potential (BAX/EAP value) in the final beverage. The case of ‘barley beers’ showed that the positive effect of barley on the oxidative beer stability was greater than the negative effect of the addition of colour malt, to adjust the colour of a 100% malt beer. In sensory comparison with beer produced with 100% malt, the beers brewed with a barley proportion up to 50% showed a slight flavour preference and up to a 75% equivalent evaluation. Copyright © 2012 The Institute of Brewing & Distilling     

EXTRUDED SORGHUM AS A BREWING RAW MATERIAL

Small scale mashes (50 g total grist) with grists containing up to 50% by weight of extruded whole sorghum produced worts of high extract yield and low viscosity. Increasing the proportion of extruded sorghum in the grist resulted in decreasing wort filtration volume, total nitrogen and free amino nitrogen content. The wort filtration behaviour of mashes containing sorghum extruded at 175°C was superior to that of mashes containing sorghum extruded at 165°C or 185°C. The results from such small scale mashing experiments suggested that extruded sorghum compared favourably to extruded barley and extruded wheat as a brewing adjunct. Worts and beers were produced on a pilot brewery scale (100 1) from grists comprising 70% malt + 30% extruded sorghum and 100% malt under isothermal infusion mashing conditions. Mashes containing sorghum extruded at 175°C showed comparable wort filtration behaviour to that of the all malt control mash whereas mashes containing sorghum extruded at 165°C or 185°C showed poor wort filtration behaviour. Worts produced from grists containing extruded sorghum fermented more quickly than the control wort and attained lower values of final gravity. The resulting beers were filtered without difficulty. Beers produced from grists containing extruded sorghum contained lower levels of total nitrogen and free amino nitrogen compared to the control beer consistent with extruded sorghum contributing little or no nitrogenous material to the wort and beer. Beers brewed from grists containing extruded sorghum were of sound flavour and showed reasonable foam stability behaviour.     

Effect of wheat malt on the concentration of metal ions in wort and brewhouse by‐products

The ionic composition of brewer's wort depends on the raw materials and processing employed. The macroelement content is usually sufficient for yeast, but some of the microelements (mainly zinc) often need to be supplemented to the wort. Wheat malt is used as an adjunct in the production of beer, replacing up to 60% of barley malt. In this study, the effect of replacing barley malt with wheat malt on the concentration of magnesium, manganese, iron and zinc ions in brewer's wort was investigated. The ionic content of both the raw materials and by‐products were analysed. Similar amounts of magnesium ions were found in wheat malt and barley malt, whereas, manganese, zinc and iron were more abundant in the wheat malt. Nevertheless, wheat malt did not cause a significant change in ion concentration in the first wort (except for magnesium; its content decreased). The ionic content in the spent grains increased owing to wheat malt addition; the concentration of ions in the wort decreased after wort boiling (Mn²⁺ and Fe) or remained unaffected (Mg²⁺ and Zn²⁺). It was concluded that the ionic composition of the wort depends mainly on the removal rate of ions from the wort during mash filtration and hot trub separation, rather than on the actual amount of ions in the raw materials. Copyright © 2015 The Institute of Brewing & Distilling     

Mashing Studies with Unmalted Sorghum and Malted Barley

The effects on wort quality when mashing with unmalted sorghum (0–100%) and malted barley (100–0%) in combination with industrial enzymes were evaluated. A mashing program with temperature stands at 50°C, 95°C and 60°C was used. Different combinations of commercial enzymes were evaluated. A heat stable α‐amylase was found to be essential for efficient saccharification. The inclusion of a fungal α‐amylase in mashes with a high sorghum content improved filtration rates to that of 100% malted barley mashes. Addition of a bacterial protease increased the amount of nitrogen solubilisation and peptide degradation. An increase of the relative proportion of sorghum in the grist resulted in decreases in wort filtration, colour, viscosity, attenuation limit, free amino nitrogen, high molecular weight nitrogen, and a corresponding increase in pH (p < 0.01). Overall the addition of malted barley in small proportions to unmalted sorghum mashes together with commercial enzymes was found to improve the potential for brewing a high quality lager beer from unmalted sorghum.     

Brewing with 100% Oat Malt

Oats are a cereal with beneficial nutritional properties and also unrealized brewing potential. Furthermore, oats can be tolerated by the majority of people who suffer from celiac disease. Malting of oats produced a malt, which was found suitable for brewing a 100% oat malt beer. The mashing regime, designed by using mathematical modelling, was successfully transferred to a pilot scale plant. The improved lautering performance of oat malt was due to its higher husk content, which also led to a lower extract content in oat wort when compared to barley wort. The protein profile of oat wort, as measured by using Lab‐on‐a‐Chip analysis, revealed that there was no significant difference in the protein profile between oat and barley wort. The fermentation of oat and barley worts followed the same trend; differences could only be seen in the higher pH and lower alcohol content of the oat beer. The flavour analysis of oat beer revealed some special characteristics such as a strong berry flavour and a lower amount of staling compounds when forced aged. This study revealed that it was possible to brew a 100% oat malt beer and that the produced beer was comparable to a barley malt beer.     

一种新型的啤酒澄清剂——-卡拉胶泡腾片的研制

目的：研究一种新型啤酒澄清剂。方法：采用单因素试验确定卡拉胶泡腾片的生产工艺：利用低温热风干燥法,干燥温度45℃,干燥时间6h。采用正交试验方法确定泡腾片配方：泡腾剂用量20%,柠檬酸:碳酸氢钠=1:1(W/W),卡拉胶用量30%,润滑剂用量2.5%。结果：在麦汁煮沸后加入泡腾片,能改善麦汁外观质量,加快过滤速度,节约硅藻土用量及能耗,酿制出的啤酒各项指标符合国家或企业标准。     

Fungal Hydrophobins in the Barley‐to‐Beer Chain

Fungal hydrophobins have been shown to induce gushing of beer. In order to study the occurrence and fate of hydrophobins at different stages of the production chain of beer, barley samples artificially infected in the field with Fusarium culmorum, F. graminearum and F. poae were collected during the growing period as well as during various stages of the malting process. In addition, naturally infected malt was brewed in pilot scale and samples were collected throughout the process. The samples were assayed for hydrophobin content using an ELISA method. The results showed that fungi produced hydrophobins that accumulated during barley grain development in the field, but that production was more pronounced during malting. Prolonged storage of barley tended to reduce the ability of fungi to produce hydrophobins in malting. Studies on the fate of hydrophobins during the brewing process revealed that mashing released hydrophobins from the malt into the wort. Some loss of hydrophobins occurred throughout the brewing process with spent grains, cold break (wort boiling) and surplus yeast. In addition, the beer filtration step reduced hydrophobin levels. Despite the substantial loss of hydrophobins during brewing, the level was high enough to induce the gushing detected in the final beer.     

Large‐Scale Study on Beer Filtration with Combined Filter Aid Additions to Cellulose Fibres

Kieselguhr or diatomaceous earth is the most commonly used filter aid for beer filtration. However, lately the use of kieselguhr has come under increased criticism. Some of the reasons for this are cost of disposal, limited resources and hazards to health from diatomite powder. One alternative to filtration with kieselguhr could be cellulose. Cellulose can be regenerated several times, is easy to dispose of, bears no health risks and as a renewable raw material is widely available. Previous single filtrations with cellulose were not satisfactory. A pre‐clarification of wort and green beer with silica sol was used in this work to improve the haze of the filtered beer. Furthermore, silica sol was added to the cellulose mixture for body‐feed during filtration. This represents a new field of application. When adding silica sol, filtrate haze was reduced in both applications. The intensity of this effect was dependent on how, when and where the material is added. Another future alternative could be rice hull ash because of its similarities to kieselguhr.     

Enhancing the hydrolysis of corn starch using optimal amylases in a high-adjunct-ratio malt mashing process

Incompletely degraded corn starch particles often seriously inhibit wort filtration and decrease a brewery’s beer productivity. Herein, the inhibiting factors of starch hydrolysis and the application of amylases to degrade residual starch were evaluated. The results showed that resistant starch and the amylopectin of corn starch were not the inhibiting factors. Almost all residual starch left in the spent grain layer was proved to be degradable by amylases. Mesophilic α-amylase was selected through a comparison of nine amylases, which increased the wort filtration rate by 44%. However, >6% of corn starch was still left after mashing when a high ratio of corn starch to water (>1:3.5) was used in liquefaction. The low water content in liquefaction was proved to be the key inhibiting factor. Considering the existing equipment and brewing technology, the application of mesophilic α-amylases should be a simple and effective method for enhancing the hydrolysis of corn starch and accelerating the wort lautering process during a high-adjunct-ratio beer brewing process.