NITROGENOUS COMPONENTS OF WORTS AND BEERS BREWED FROM ALL-MALT AND MALT PLUS WHEAT FLOUR GRISTS

Worts and beers prepared from grists containing malt and wheat flour contain more and larger proteins than those prepared from grists containing only malt. These properties are related to the superior foam stability possessed by malt plus wheat flour beers. Malt solubilizes some of the wheat flour protein during mashing without subjecting it to significant proteolysis. Only very limited enzyme inhibition is exhibited. Finings residues in draught beers increase the precipitability of protein by sodium chloride and are particularly effective with malt plus wheat flour beers. The proteinaceous material isolated in this way has marked foam-stabilizing properties. The relationship between the protein removed by chilling the beer and salt-precipi-table protein and foam stability is also examined. Non-fining hazes from certain malt plus wheat flour beers are related to other beer protein fractions and some recommendations for brewery practice are made.     

APPLICATIONS OF FAST PROTEIN LIQUID CHROMATOGRAPHY (FPLC) TO THE ANALYSIS OF THE NITROGENOUS CONSTITUENTS OF BEER

The nitrogenous constituents of beer were investigated by several Fast Protein Liquid Chromatography (FPLC) techniques. Size exclusion chromatography of dialysed beer material using columns of Superose 6 and Superose 12 suggested that beer polypeptide material was distributed across a wide relative molecular mass (Mr) range with discrete fractions of high Mr (Mr 300 000, Mr 500 000), Mr c60 000, Mr c40 000 and relatively low Mr (Mr 5 000–20 000). The composition of fractions Mr >40 000 and Mr 40 000–60 000 was investigated by ion exchange chromatography. Differences were detected in the elution profiles of fractions prepared from beers brewed from grists comprising 100% malt, 80% malt plus 20% torrfied wheat and 100% malted wheat consistent with differences in the polypeptide composition of these fractions. The Superose 12 column, although designed for the fractionation of high molecular weight components, also provided a method of fractionating low molecular weight nitrogenous materials directly from beer (for example fractions containing purine nucleosides). Reverse phase chromatography was employed in the analysis of beer peptides and demonstrated the complex composition of beer peptide fractions.     

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.     

Brewing with 100% green malt – process development and key quality indicators

Brewing with undried, germinated (green) malt has the potential to lower energy and water usage in the malting and brewing chain. However, doing so introduces technical and biochemical (flavour) challenges. Beers were brewed using 100% green malt (n = 3) or kilned pilsner malt (n = 3), prepared from the same batch in each case, utilising the pilot brewery at KU Leuven (2.5 hL). Three further pairs of beers were brewed whereby the green malt was pre-steeped under deaerated water for 1 hour; this procedure was previously shown to lower LOX activity in green malt. Six green malt beers were brewed with acceptable specifications in terms of pH, alcohol content, foam stability and colour. No significant taints or obvious defects were detected in green malt beers. Increased S-methyl methionine levels were measured in worts and beers made from green malt, however DMS concentrations in the finished beers did not differ significantly from the reference beers. Furthermore, the results demonstrated promising indicators for flavour stability, such as reduced TBI, lower residual FAN and trihydroxy fatty acid (THFA) levels in brews using untreated green malt. Using re-steep water in green malt brewing (for reasons of water economy), however, increased THFA levels, possibly because oxygen uptake was not adequately controlled at this step. Whilst further process optimisations are undoubtedly required, it is shown that an acceptable lager style beer could be brewed to a specification not dissimilar to that of a kilned malt control beer, using 100% green malt with intact rootlets. © 2020 The Authors. Journal of the Institute of Brewing published by John Wiley & Sons Ltd on behalf of The Institute of Brewing & Distilling     

Occurrence of biogenic amines in beers produced with malted organic Emmer wheat (Triticum dicoccum)

Because several groups of microorganisms are able to decarboxylate amino acids, the presence of biogenic amines (BA) can be seen as an index of the microbiological quality of the brewing process. BAs were quantified for the first time in the intermediate products and craft beers produced with malted organic Emmer wheat (Triticum dicoccum) in a small size brewery in order to assess the possible presence of critical control points related to biological hazard in the brewing process. BA levels in beers produced exclusively from malted organic Emmer wheat were between 15.4 and 25.2 mg l^–1 in the samples of light beer (Lt) and between 8.9 and 15.3 mg l^–1 in double malt beers (DM) ready for consumption (the beers stored for 90 days at 1–2°C). Cadaverine and tyramine were the main BAs in the Lt and DM beers, respectively. Increased concentrations of BAs seemed to be more related to the heat treatment of the processing product during mashing and wort boiling, rather than to the fermentation process. Much lower concentrations were found in finished beers obtained from 50% malted organic Emmer wheat and 50% malted barley (up to 3.2 mg l^–1) or from 30% malted Emmer wheat (up to 8.3 mg l^–1). Thus, Emmer wheat malt can be a useful alternative to wheat and spelt for the production of beer with a limited content of BA, if the processing technology is kept under control.     

FRACTIONATION OF HIGH MOLECULAR WEIGHT POLYPEPTIDES FROM BEER USING TWO DIMENSIONAL GEL ELECTROPHORESIS

High molecular weight polypeptides from beer were fractionated by a two dimensional gel electrophoretic method comprising isoelectric focusing in the first dimension followed by gradient gel electrophoresis in the second dimension. Silver stained gels revealed a complex pattern of spots which is consistent with individual polypeptide species having both discrete isoelectric points and molecular weights. The pattern of silver stained spots was reproducible both within and between beers and was independent of the sample preparation method or the composition of the sample solubilisation mix. Beers produced from grists containing malt plus 20% wheat flour were shown to contain four polypeptides of approximate molecular weight 30 000, 30 000, 16 000 and 15 000 which were absent from all malt control beers.     

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.     

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.     

Consumer interest in specialty beers in three European markets

This study explores the quality perception of specialty beers (SBs) in Italy, Spain and Poland. Five-hundred and fifty mainstream beer consumers were enrolled in this study (two-hundred and thirty Italians, one hundred and sixty Poles and Spaniards respectively). The authors adopted a conjoint rating experiment in which the respondents were given forty SB profiles to evaluate. Each profile was described on six attributes (malt type, adjuncts, alternative source of sugars, characterizing ingredients, sensory characteristics, and retail price) varied at different levels and were asked to state his/her preference for each profile on a 9-point scale of interest. The results of this study showed that the ideal SB: (1) for the aggregate Polish panel is brewed from malted wheat, raw wheat, honey, and tropical fruits, is alcoholic and is priced below 2.00 Euros; (2) for the aggregate Italian panel consists of a beer brewed from malted wheat, maize, honey, and vanilla, is blonde and costs a maximum of 2.00 Euros; (3) for the aggregate Spanish panel is brewed from malted wheat, rye or maize, vanilla, is fruity and is priced below 2.00 Euros. The heterogeneity of interest in specialty beers observed in the three countries under test requires for the adaptation of a SB specifically to each culture in which it is sold. In this process of customization, brewers must take into account that gender modulates the effect of culture on consumer interest in SB sensory characteristics and ingredient formulation.     

FRACTIONATION OF SMALL PEPTIDES FROM BEER

Small peptides (MW<1000) were isolated from beer by hollow fibre ultrafiltration followed by column chromatography using the gel matrix Sephadex LH20. This simple procedure enabled the isolation of small peptides relatively free of other low molecular weight nitrogenous compounds. Analysis of the composition of subfractions from the small peptide fraction from pilot brewery beer and a commercial beer using reverse phase HPLC showed superior resolution of individual components compared to previously reported analytical techniques and demonstrated the presence of many peptide components. Acid hydrolysis and amino acid analysis of small peptide subfractions showed that the principal amino acid in each subfraction was glutamic acid/glutamine consistent with the release of peptides by proteolytic degradation of barley and malt proteins.     

Faba bean as a novel brewing adjunct: Consumer evaluation

The starch in the grains of legumes, such as faba bean (Vicia faba L.), offers an environmentally sustainable raw material for the brewing industry as their entire nitrogen fertiliser requirement can be provided by the natural process of biological nitrogen fixation. Faba bean is, therefore, distinguished from species such as spring barley (Hordeum vulgare L.), which require large amounts of synthetic nitrogen fertiliser. Consumer analysis of beer produced with faba bean as an adjunct compared with barley malt beers has not previously been assessed. This study evaluated the potential of beers brewed using 30% (w/w) dehulled bean (kernel) flour as an adjunct to malted barley, using a series of quantitative sensory tests. The first, a blind acceptance test with inferred preference, found no statistically significant difference in the taste score of the bean kernel flour adjunct beer when compared with conventional beer. In the second acceptance test, the knowledge that the beer was produced using beans did not affect the overall consumer impression of the beer, regardless of how this information was presented. These results suggest that the use of faba beans in brewing does not impact negatively on the taste or acceptability of the resultant beer. © 2019 The Institute of Brewing & Distilling     

比利时/德国小麦啤酒风味物质差异研究

以大麦芽、小麦芽和未发芽的小麦为原料,添加酒花、橘皮和芫荽籽,使用上面发酵酵母No.303,酿造比利时风格和德国风格小麦啤酒。该研究介绍了两种风格小麦啤酒的酿造工艺,对两种风格的成品小麦啤酒进行风味物质检测分析以及感官品评,探讨了比利时风格小麦啤酒和德国风格小麦啤酒风味物质的差异。结果表明,比利时风格小麦啤酒乙醛含量更为适宜（约为2.6 mg/L）,高级醇和乙酸含量较高（分别为113 mg/L和160 mg/L）,酯类物质含量偏低（约为50 mg/L）,成品啤酒橘香味突出,但酯香味不够充足;德国风格小麦啤酒乙醛和酯类物质含量略高（分别为3 mg/L和63 mg/L）,高级醇含量稍低（约为104 mg/L）,乙酸含量适宜（约为135 mg/L）。     

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     

FLAVOUR FROM CRYSTAL MALT

Beers brewed from grists containing between 3% and 30% of crystal malt have been examined in order to identify the volatile substances contributing to the characteristic flavour. Several oxygen, nitrogen and sulphur heterocyclic compounds together with certain fusel oil components are present at higher levels in beers brewed with crystal malt. Some of these compounds have also been isolated from the malt itself and from heat-treated model systems. The results are consistent with these compounds being derived from sugars and amino-acids via Amadori rearrangement products.     

RAPID METHODS FOR DETERMINING THE HIGH MOLECULAR WEIGHT POLYPEPTIDE COMPONENTS OF BEER

Size exclusion chromatography and a coomassie blue dye-binding assay were used to investigate the high molecular weight polypeptide fractions of beer. Size exclusion chromatography using small colums of Sephadex G25, G50 (10 ml) and G75 (20 ml) together with an automated FPLC system enabled the rapid isolation of high molecular weight polypeptide fractions of beer. Size exclusion chromatography using small columns of Sephadex was investigated as a method for the determination of the total high molecular weight polypeptides in beer. The results from the analysis of a series of pilot brewery beers produced under standardised brewing conditions showed that the head retention value of a beer correlated with the content of high molecular weight polypeptide material regardless of the molecular weight fraction assayed. Both methods may be used to monitor the high molecular weight polypeptide content, predict the head retention value of a beer and are sufficiently rapid for routine use in the quality control laboratory.     

Wheat Variety and Barley Malt Properties: Influence on Haze Intensity and Foam Stability of Wheat Beer

Laboratory wheat beers were brewed with different wheat varieties of different protein content (8.7–14.4%) and with five different barley malts, varying in degree of modification (soluble protein: 3.9–6.9%). In a first series of experiments, it was investigated whether wheat positively influences the foam stability, a major characteristic of wheat beers. NIBEM and Rudin (CO₂) foam analyses revealed that the effect of wheat on foam stability depended on the barley malt used for brewing. When using malt with high foaming potential, wheat exerts a negative influence. However, wheat added to over‐modified malt with less foam promoting factors, ameliorates beer foaming characteristics proving that wheat contains foam active compounds. In addition, Rudin (N₂) values suggested that wheat positively influences foam stability by decreasing liquid drainage, probably caused by a higher beer viscosity and/or a finer foam bubble size distribution. Furthermore, the haze in wheat beers, which is another important quality characteristic of these beers, was investigated. Permanent haze readings of the 40% wheat beers were lower than 1.5 EBC haze units. For 20% wheat beers, an inverse relation between the permanent haze (9.4–19.3 EBC haze units) and the protein content of the wheat was established. The barley malt used for brewing also influenced permanent haze readings. A positive correlation between the modification degree of the malt and the permanent haze intensity was found. It was concluded that the choice of raw materials for wheat beer brewing considerably influences the visual properties of the beer.     

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。     

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

All-malt Pilsner beers were brewed with proanthocyanidin-free malt (ant 13 × 13 × Rupal). Hopping was with n-hexane tannin-free hop extract with or without n-hexane extracted hop residue or with whole leaf hops. The different beers were analysed chemically and presented to an expert panel to detect possible preferences and differences in bitterness and astringency. The impact of hop proantho-cyanidins on haze formation is comparable to that of malt proanthocyanidins. No differences between the beers were found in triangular tests. Statistical analysis of the paired comparison tests showed that hop proanthocyanidins do not contribute to the bitterness of beer since beer brewed with tannin-free hop extract is slightly more bitter than beer brewed with whole leaf hops. No differences in astringency were noted between beers brewed with or without hop proanthocyanidins and it was found that the panel expressed a very slight preference for beer brewed with n-hexane hop extract over beer brewed with both n-hexane hop extract and extracted hop residue.     

THE BITTERNESS OF HOP-DERIVED MATERIALS IN BEER

The bitterness of trans- and cis-isohumulones obtained both from beer and by alkaline isomerization of α-acids has been compared with the bitterness of hop resins and other materials extractable from beer. Trans-isohumulones and cis-isohumulones, obtained either from beer or by alkaline isomerization of α-acids, and hulupones have been shown to be the most bitter materials. Hulupones were only slightly less bitter than trans-and cis-isohumulones, which showed little difference in bitterness value when prepared directly, although the collective tasting results show a bias for a greater bittering associated with the cis-component. The hulupones, like the parent β-acid, possessed a distinctive aromatic flavour. α-Acids and other unidentified materials obtained from beer brewed with hops of a normal age have been found to possess a much lower level of bitterness. The observation that aged hops impart normal levels of tastable bitterness to beer has been confirmed at significant brewery level (60 brl.) using grists consisting solely of six year old hops. Approximately 35% of this bitterness is provided by isohumulones and the greater part of the remainder arises from materials soluble in low-boiling paraffinic hydrocarbon solvents. A known β-acid oxidation material has been isolated from fresh and old hops and from beers brewed with either fresh or old hops.     

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.