USE OF FORMALDEHYDE FOR THE REDUCTION OF THE ANTHOCYANOGEN CONTENT OF WORT*,†

Reduction in wort anthocyanogen content is achieved effectively when formaldehyde is introduced to the mash at the beginning of the mashing operation. Concentrations of 50 p.p.m. of formaldehyde with respect to the malt (equivalent to about 5 p.p.m. with respect to the final wort volume) are effective in reducing the anthocyanogen content by about 30%. Treatments four times as strong reduce the anthocyanogen content by 60–70%, and the effect is accompanied by a fall of up to 10% in the soluble nitrogen content of the wort. It seems likely that a condensation reaction occurs between anthocyanogens and a nitrogenous fraction of the wort. Under the conditions quoted, formaldehyde residues in the finished beers are less than 0·2 p.p.m. and are no greater than those observed in corresponding untreated control beers. Beers produced from treated mashes exhibit great non-biological stability, but are quite normal in other respects. The effect of formaldehyde on the anthocyanogen contents of worts and beers is of substantial theoretical interest and it is probable that it will also have a commercial application.     

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.     

FLAVOUR AND HAZE STABILITY DIFFERENCES DUE TO HOP AND MALT TANNINS IN ALL-MALT PILSNER BEERS BREWED WITH PROANTHOCYANIDIN-FREE AND WITH REGULAR MALT

All-malt Pilsner beers were brewed with and without hop and malt proanthocyanidins by using regular malt and whole leaf hops as well as proanthocyanidin-free malt and n-hexane tannin-free hop extract. The different beers were analysed chemically and presented to an expert panel to detect possible differences in bitterness and astringency. The impact of proanthocyanidins on the formation of haze was demonstrated clearly. No differences between the beers were found in triangular tests although their levels of total polyphenolics and anthocyanogens differed by about 225 and 85 mg/litre. Statistical analysis of the paired comparison tests showed only very slight differences between beers with or without hop and malt proanthocyanidins. Thus, proanthocyanidin-free beer was considered less than slightly more bitter and astringent than regular beer and there was a very slight preference for the latter.     

SMALL SCALE MASHING EXPERIMENTS WITH GRISTS CONTAINING HIGH PROPORTIONS OF RAW SORGHUM

Small scale mashes (50 g total grist) with grists containing high proportions of raw sorghum (50%–80% malt replacement) showed high values of extract recovery and produced worts of lower total nitrogen, free amino nitrogen, viscosity and colour but higher values of pH compared to worts produced from all malt mashes. Increasing the proportion of raw sorghum in the grist relative to malt resulted in a decline in extract recovery, wort total nitrogen, free amino nitrogen and an increase in wort pH. Addition of industrial enzyme preparations to mashes containing raw sorghum resulted in higher values of extract recovery (enzyme preparations containing α amylase and β glucanase), higher values of wort total nitrogen and free amino nitrogen (enzyme preparations containing a neutral proteinase) and decreased wort viscosity (enzyme preparations containing β glucanase or cellulases) compared to worts produced from untreated mashes. Worts and beers were produced on a pilot brewery scale from 50% malt and 50% polished (whole) sorghum (single decoction mashing regime) and 20% malt and 80% raw sorghum supplemented with an industrial enzyme preparation (double mashing regime). Mashes comprising 50% malt and 50% polished sorghum showed comparable wort filtration behaviour (lautering) to that of control mashes (70% malt and 30% maize grists) whereas wort produced from 20% malt and 80% raw sorghum filtered slowly. Worts produced from grists containing sorghum were of high fermentability and showed lower levels of total nitrogen and free amino nitrogen compared to control worts. Analysis of worts produced from small scale mashes containing raw sorghum and a pilot brewery scale mash comprising 20% malt and 80% raw sorghum demonstrated that the levels of total nitrogen and free amino nitrogen were higher than expected from the reduction in the malt content of the mash, consistent with the release of nitrogenous components (polypeptides, peptides and amino acids) derived from sorghum into the wort. Beers produced from 50% malt and 50% polished sorghum and 20% malt and 80% raw sorghum were filtered without difficulty and were of sound flavour. Beers produced from 50% malt and 50% polished sorghum contained lower levels of isobutanol, 2-methylbutanol, dimethylsulphide and higher levels of n propanol and diacetyl compared to control beers.     

PHENOLIC ACIDS IN BEERS AND WORTS

The total contents of phenolic acids measured by high-performance liquid-chromatography were 5–8 mg/litre in beers brewed in Ireland whereas 16–40 mg/litre were present in four other beers. In all beers the predominant phenolic acids were vanillic, p-coumaric and ferulic acids. Free phenolic acids were extracted from Emma barley grains and malt in very small amounts (15–28 mg/kg) but larger quantities (191 mg/kg) were released on mashing the malt. Little change occurred in the contents of phenolic acids on processing a lager wort through to the finished beer. Treatment with excess Polyclar AT removed astringent flavour and phenolic acids from an experimental ale but this flavour loss could not be accounted for by the adsorption of phenolic acids. The flavour threshold for a nine-component phenolic acid mixture in lager was between 50 mg/litre and 100 mg/litre.     

LOW PROANTHOCYANIDIN MALTS FOR PRODUCTION OF CHILLED AND FILTERED OR FINED BEER

Malts which conform to most commercial specifications can be prepared from Galant barley, which is low in anthocyanogens. However, the malting performance of this variety is only medium and considerable care is required during kilning in order to avoid excessive colour development. Beers brewed from Galant malt have greatly improved chill haze stability, although flavour stability is not significantly affected. Fining and filtration studies on rough beer and forcing tests for the development of non-biological haze in finished beer indicate that the use of Galant malt greatly reduces the extent of precipitation of particulate matter during brewing, conditioning and subsequent storage. This can result in considerable savings in the use of finings, and in longer filter runs since levels of addition of body feed can be reduced. It is suggested that the use of low anthocyanogen malts could, with some beers, reduce the necessity for chilling prior to and during filtration.     

Pilot Scale Production of a Lager Beer from a Grist Containing 50% Unmalted Sorghum

Pilot scale (1000 L) brews were carried out with a grist comprising of unmalted sorghum (50% of total wet weight of grain) (South African variety) and malted barley (50% of total wet weight of grain) grist using a mashing program with rests at 50°C, 95°C and 60°C. Mashes were supplemented with a high heat stable bacterial α‐amylase, a bacterial neutral protease and a fungal α‐amylase. A control brew containing 100% malted barley was also carried out. Saccharification difficulties were encountered during mashing, and extraction of the grist was lower for the sorghum mashes. The sorghum mashes showed comparable lautering behaviour to that of the control mash. At mashing off the sorghum worts were starch positive. Apparent degree of fermentation of the sorghum gyles were less than the control gyles. Green beer filtration proved unproblematic. The sorghum beers compared quite closely with the control beer with regard to colour, pH and colloidal stability. Foam stability deficiencies were apparent with the sorghum beer. However, the fermentability of the sorghum worts were lower. Hence the sorghum beers were lower in total alcohol. Sensory analysis indicated that no significant differences existed between the sorghum beer and both the control beer and a commercial malted barley beer with regard to aroma, mouth‐feel, after‐taste and clarity. However, the sorghum beer was found to be significantly different to both of the other beers with regard to colour, initial taste and foam stability.     

Comparison of the impact on the performance of small‐scale mashing with different proportions of unmalted barley,Ondea Pro®, malt and rice

The impact of using different combinations of unmalted barley, Ondea Pro® and barley malt in conjunction with a 35% rice adjunct on mashing performance was examined in a series of small scale mashing trials. The objective was to identify the potential optimal levels and boundaries for the mashing combinations of barley, Ondea Pro®, malt and 35% rice (BOMR) that might apply in commercial brewing. Barley and malt samples used for the trials were selected from a range of Australian commercial barley and malt samples following evaluation by small‐scale mashing. This investigation builds on previous studies in order to adapt the technology to brewing styles common in Asia, where the use of high levels of rice adjunct is common. Mashing with the rice adjunct, combined with differing proportions of barley, Ondea Pro® and malt, resulted in higher extract levels than were observed for reference mashing, using either 100% malt reference or 100% barley reference and Ondea Pro® enzymes. Synergistic mashing effects between barley, Ondea Pro® and malt were observed for mash quality and efficiency parameters, particularly wort fermentability. The optimum levels of barley in the grist (with the relative level of Ondea Pro®) were assessed to be in the range 45–55% when paired with 10–20% malt and 35% rice. When the proportion of malt was reduced below 10% of the grist, substantial reductions in wort quality were observed for wort quality parameters including extract, lautering, fermentability, free amino nitrogen and haze. Extension of this new approach to brewing with rice adjuncts will benefit from further research into barley varietal selection in order to better meet brewer's quality requirements for the finished beer. Copyright © 2016 The Institute of Brewing & Distilling     

Effects of arabinoxylan solubilization on wort viscosity and filtration when mashing with grist containing wheat and wheat malt

Arabinoxylans are partially water-extractable, high-molecular-weight polymers that contribute to the problems of viscosity and membrane filterability during beer brewing. These problems are more pronounced when wheat and wheat malt are used as adjuncts due to their higher arabinoxylan contents and higher molecular weights. This paper aimed at investigating the effects of mashing temperature, time, grist size and liquor:grist ratio on the solubilization of arabinoxylans. Results indicated that increasing the mashing temperature generally increased the amount of arabinoxylans released into the wort. When greater proportions of wheat or wheat malt were used as adjunct, higher arabinoxylan contents in the final wort were observed. The more finely ground the grist, the more were arabinoxylans released into the wort. When more diluted mashes were used, more efficient solubilization of arabinoxylans was observed. The effects of arabinoxylan content and β-glucan content on the wort viscosity were also examined using a General Linear Model (GLM). There was a good correlation (R² = 0.98) between wort viscosity and its arabinoxylan and β-glucan contents.     

Differences in protein content and foaming properties of cloudy beers based on wheat malt content

To investigate differences in protein content, all barley malt beer, wheat/barley malt beer and all wheat malt beer were brewed, and the protein during mashing, wort, fermentation and beer determined. It was shown that protein was mainly extracted during mashing and the protein rest phase, decreased in the early stages of fermentation and remained almost steady during wort boiling and cooling, in the middle and late stages of fermentation. By separating beer foam from beer, similar protein bands of 51.7, 40.0, 27.3, 14.8, 6.5 and < 6.5 kDa appeared in the three beers, defoamed beers and beer foams using the sodium dodecyl sulphate polyacrylamide gel electrophoresis. Quantitatively, protein bands of 6.5–14.8 and <6.5 kDa had the highest contents in the three beers. Unique bands at 34, 29.2, 23.0, 19.7 and 17.7 kDa were found in beer, defoamed beer and beer foam from wheat beer and all‐wheat malt beer, respectively. Wheat beer foam showed the best foam stability and the protein in all barley malt beer showed the best migration to the foam. The beer foam properties were influenced by not only protein content but also protein characteristics and/or origin. It is suggested that the barley malt contributed the beer foam ‘skeleton protein’ while protein components from wheat malt kept the foam stable. © 2018 The Institute of Brewing & Distilling     

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。     

Effects of Mashing Parameters on Mash β‐Glucan,FAN and Soluble Extract Levels

To gain further technological knowledge of mashing, pilot scale mashing trials were carried out varying mashing programme (upward/isothermal mashing), milling procedure, grist:liquor ratio, time of mash stands, and grist modification level (well and poorly modified malt). During mashing β‐glucan, free amino nitrogen (FAN) and extract contents were analysed as key indicators for cytolysis, proteolysis, and amylolysis, respectively. The malt modification was of major impact for the β‐glucan release in contrast to a variation of milling procedure and of grist:liquor ratio. Extended stands lead to increased final values only for poorly modified malt. Similarly, FAN release was predetermined by malt modification while variation of milling and of grist:liquor ratio was not relevant in contrast to stand extension. None of the variations applied influenced extract yield as long as gelatinization temperature was reached. Greatest gains occurred around 57°C. In conclusion, wort quality is critically determined by malt modification. Mashing with well modified malt in combination with short stands should result in a mash of low β‐glucan and sufficient FAN level without losing extract yield. However, for poorly modified malt the variation of mashing parameters has an impact on the key indicators in which cytolysis plays the dominating role.     

PHENOLIC CONSTITUENTS OF BEER AND BREWING MATERIALS. II. THE ROLE OF POLYPHENOLS IN THE FORMATION OF NON-BIOLOGICAL HAZE

Simple and polymeric polyphenols differ in the way in which they influence the development of chill and permanent hazes in bottled beer. The addition of simple anthocyanogens to beer causes a marked increase in the rate of haze formation whereas added polymeric materials induce immediate and intense turbidities. Beer anthocyanogens constitute a class of materials ranging in complexity from simple compounds to heterogeneous polymers which sometimes include polyphenolic units that are incapable of yielding anthocyanidins with acid. The extent to which the various anthocyanogens present in beer are involved in haze formation is not reflected by their contributions to the overall anthocyanogen value of the beer. Haze-inducing polymers which contain no anthocyanogen residues may also be present in beer. The nature and origin of polyphenolic substances in beer and the methods by which they may polymerize to give immediate haze precursors are discussed.     

THE USE OF FORMALDEHYDE IN RESTEEPING

Small-scale malting trials showed that resteeping in a solution of formaldehyde was more uniformly effective than resteeping in water in reducing rootlet yield and the overall malting loss. The hot water extract, the fermentability of the wort, and the formol nitrogen were the same in worts from malts prepared by resteeping in water or formaldehyde solutions. However, cold water extract was reduced, as was the total soluble nitrogen, by the presence of formaldehyde. The anthocyanogen level in the wort was reduced by about 73% when formaldehyde was used in the resteep liquor. The residue of formaldehyde in the unboiled wort was about I p.p.m. It is considered that, in view of the improved resteeping performance and the expected increase in beer stability resulting from the reduction in anthocyanogens and wort nitrogen, the use of formaldehyde in resteeping is worth evaluating on a larger scale. In addition the use of formaldehyde in the resteep liquor prevented fouling by micro-organisms and resulted in a cleaner malt.     

EFFECT OF CALCIUM IONS IN SORGHUM BEER MASHING

One of the problems in sorghum beer brewing is that of sugar production. This is because sorghum malts are low in diastatic activity, the grist contains a high proportion of adjunct and in some brewing processes conversion is carried out at pH 4. Since the positive effects of calcium ions on alpha-amylase activity are well described, the use of additional calcium in sorghum mashing was investigated. Mashing at pH 4.5 in the presence of 0.1% calcium acetate (227 ppm Ca) resulted in almost complete conservation of diastatic activity during conversion and higher reducing sugar production compared with tap water (31 ppm Ca). At a mash pH of 4, a calcium ion concentration of approximately 200 ppm gave maximum reducing sugar production and wort yield and increased extract. Under these conditions, some alpha-amylase activity was detected at the end of the conversion, whereas without calcium no alpha-amylase activity was detected. It, therefore, appears that improved conversion took place due to the conservation of alpha-amylase activity by calcium ions. The inclusion of additional calcium ions in sorghum beer mashes also enabled the same amount of sugar production compared with straight tap water but using a substantially lower proportion of malt in the grist.     

THE USE OF EXTRUDED BARLEY,WHEAT AND MAIZE AS ADJUNCTS IN MASHING

The principles of extrusion cooking are summarised. In small scale trials good extracts were obtained from extruded barley when it was mashed with industrial enzymes, using a programmed temperature cycle. Extruded barley, wheat and maize and wheat flour yielded acceptable levels of extract when mashed with lager malt (70%) using a programme with 1 hour rests at 50°C and 65°C. The extracts obtained from these grists were increased above those obtained from grists of lager malt alone and the viscosities of the worts were reduced when the mashes were supplemented by preparations of bacterial enzymes. Enzyme additions also improved extract recoveries from all-malt mashes and reduced the viscosities of the derived worts. Using a temperature programmed mashing cycle and supplementary enzymes beers were prepared from a lager malt grist and grists in which the lager malt was partly replaced, by 30%, with extruded barley or extruded wheat, or extruded maize or wheat flour pellets. In every case wort was recovered relatively easily, the worts fermented normally and the beers were all fully acceptable, although their flavours did differ. However, in contrast to results of preliminary brewing trials, the head retentions of the beers made with adjuncts were unusually low, possibly because of particular enzyme additions.     

FLAVOUR STABILITY OF ALES BREWED USING HYDROLYSED MAIZE SYRUP—SENSORY AND ANALYTICAL ASPECTS

Whereas ales brewed entirely from malt had flavour-lives of 12 weeks, those produced from 70% malt/30% hydrolysed maize syrup had flavour-lives of at least 25 weeks. The latter beers were of sound flavour and quality, and no difficulties were experienced during their production. Their initial flavour was similar to that of beers brewed using an all-malt grist. Analysis by gas chromatography coupled mass spectrometry showed that the all-malt beer underwent a greater degree of change during natural aging than did the beer brewed with maize syrup. A number of compounds, including a series of glycerol/acetaldehyde acetals, have been identified for the first time in beer; the latter compounds were found to increase in level during aging.     

HYDROPHOBIC POLYPEPTIDE EXTRACTION DURING HIGH GRAVITY MASHING— EXPERIMENTAL APPROACHES FOR ITS IMPROVEMENT

The aim was to establish if a substantial increase in hydrophobic polypeptides could be achieved during high gravity mashing. When worts with gravities ranging from 5–20°P were analysed for hydrophobic polypeptide content it was found that there was no appreciable increase in hydrophobic polypeptide levels. Remashing of the spent grains from low and high gravity mashes demonstrated that this resulted from inefficient extraction of hydrophobic polypeptide levels during the mashing process. For example, wort produced from remashed high gravity spent grains contained 150 mg/L hydrophobic polypeptides compared to only 10 mg/L in the low gravity remashed spent grains. Experiments were conducted, employing standard mashing techniques, in an attempt to increase the extraction of hydrophobic polypeptides during high gravity mashing. Thus the use of gypsum, proteolytic stands, varying liquor to grist ratios and wheat malt addition were all investigated for their effect on hydrophobic polypeptide extraction during high and low gravity mashing. Wort analysis demonstrated that none of the techniques employed had a significant effect on hydrophobic polypeptide extraction. When wort from remashed spent grains was used as mashing in liquor for a fresh mash and the resultant worts analysed for hydrophobic polypeptides it was observed that no increase in hydrophobic polypeptide extraction was achieved. For example, wort from the remashed high gravity spent grains, containing 140 mg/L hydrophobic polypeptides, when used as mashing-in liquor, produced no increase in hydrophobic polypeptide levels in the resultant high gravity wort (230 mg/L) when compared to a high gravity wort produced using distilled water as mashing-in liquor (255 mg/L). It is therefore concluded that a saturation point has been reached and no more hydrophobic polypeptides can be extracted during mashing regardless of the procedures employed.     

Release of phenolic flavour precursors during wort production: Influence of process parameters and grist composition on ferulic acid release during brewing

In this study, the effects of mashing variables such as mashing-in temperature, time and pH, mash thickness, grist coarseness and composition, and stirring regime on the release of ferulic acid were examined. Ferulic acid is a precursor for the formation of flavour-active volatile phenols and a potent natural antioxidant in beer. Given one barley malt variety, the multitude of choice in setting various process parameters and adding brewery adjuncts during brewhouse operations can give rise to worts with widely varying ferulic acid levels. A clear difference in temperature- and pH-dependence between the release of the water-extracted and the enzymatically hydrolyzed fraction was found. The T,t-dependencies of arabinoxylan-degrading enzyme activities were correlated with ferulic acid release during mashing. Results from laboratory-scale mashing experiments were validated with those from a pilot-scale (5 h) wort production process. Enhancing the enzymatic release of phenolic flavour precursors from bound forms during mashing can greatly enhance the phenolic aroma potential of wort. Optimising this precursor release during mashing may be a means for controlling final volatile phenol levels in beer.     

Brewing with Rice Malt — A Gluten‐free Alternative

The preparation of beer‐like beverages with rice malt as the only raw material is reported. Several tests were performed on a laboratory scale and in a 25 L‐capacity pilot plant. Both the decoction and the infusion procedure were tested; malt and water were mixed in a ratio 1:3.5 for both methods and the mash was brewed without adding exogenous enzymes. The obtained worts were fermented using bottom fermenting yeasts, while “beers” were re‐fermented utilizing top fermenting yeasts and adding either sterile wort or sugar. A maximum ethanol of 4.5% vol. was obtained after the primary fermentation from an initial wort with an original gravity of 11.8°Plato. All parameters of the beer were found to be acceptable using a standard beer analysis. Owing to a suitable hop addition, an aroma very similar to that of a normal beer was obtained.