Why was the work done: With respect to terroir, ‘To be or not to be,’ (Hamlet, Shakespeare) is a key question for maltsters and brewers for malt and beer quality. Terroir is a sparsely studied aspect of malt quality, despite it being an important component of added market-value in wine since ancient times. The ‘sense of place’ imbued by terroir is an expression of the growth of a grape variety in a specific region with respect to local climate, soil, microbiome, elevation/aspect of the vineyard, viticultural and wine making methods. Similar corollaries to wine terroir can be drawn for hops and malting barley. How was the work done: A comprehensive review of the literature was undertaken to identify reports of terroir in barley/malt quality. Where possible, the discussion was extended by consideration of appropriate unpublished data. What are the main findings: The primary influence of terroir on malt is grain protein content (GPC). This appears, in part, to be controlled by the daylength during grain maturation. Increasing day length typical of grain maturation in Australia tends to be associated with a lower GPC, while decreasing daylength during grain maturation in Canada is associated with a higher protein content. GPC is positively correlated with diastatic power, beta-amylase activity and foam positive proteins such as protein Z4 and hordeins. Conversely, GPC is inversely correlated with extract and Kolbach Index (KI). Interestingly, lower protein barley tends to produce higher KI malts that result in wort with greater flavour complexity and desirability. The level of ionic micronutrients (cations, anions) including calcium and zinc are understudied aspects of malt quality. It is evident that there is significant variation in the ionic micronutrient content of malt produced from different international regions and between regions of the same country which would be an expression of terroir. Lastly, the microbiome of barley/malt shows influences of terroir such as the deleterious impacts of Fusarium head blight on malt quality including gushing and mycotoxins. Variation in terroir will also have more subtle impacts, both desirable and undesirable, on malt quality for the contribution of beneficial enzymes (e.g., cell wall degrading enzymes) or for the propensity of barley to impart malt components into wort (e.g., arabinoxylan) that have been implicated in premature yeast flocculation (PYF) and undesirable beer quality. Why is the work important: The concept of terroir in malt quality has important implications for the efficiency of mashing, lautering, fermentation and beer quality.

Beer flavor is primarily impacted by malt kilning and the choice of yeast/hops in the beer recipe. Although barley malt is the material backbone of most beers, variety has until recently been largely overlooked with respect to flavor differences. In this study, 11 malt variety samples from multiple Australian and international (UK, Canada, China) growing regions were infusion mashed (65 degrees C) at laboratory scale to produce unboiled wort to investigate differences between the flavor profiles observed with sensory assessment and headspace-SPME gas chromatography-mass spectrometry (HS-SPME GC-MS). Sensory evaluation identified wort flavor differences with the control heritage samples, Maris Otter/Schooner, having the highest overall flavor complexity and acceptability. The Chinese malted Chinese/Canadian samples had the lowest overall flavor complexity rankings. Overall, flavor complexity was correlated with KI, malt protein (negative), and beta-glucosidase (negative), while sweetness intensity was correlated with limit dextrinase and pH. HS-SPME GC-MS analysis focused only on compounds that were significantly different between varieties (ANOVA, P <= 0.05). Overall, 107 compounds were identified with significantly different levels between the varietal worts. The resultant PCA plots (overall, aldehydes, alcohols, esters, organic acids, terpenes, ketones) supported the sensory assessment, with Maris Otter and the Australian samples clustering in different PCA sectors compared to the Chinese malted Canadian/Chinese samples. These findings provide a basis for key compound identifications that influence malt flavor through the brewing process. The results have the potential to assist barley breeders in selecting optimized germplasm for future variety development and can assist maltsters and brewers to consistently target desired flavors for finished beers and potentially whisk(e)y.

A largely defined series of hydrolytic enzymes active during malting and/or mashing, substantially determine the quality, profitability, and efficiency of the brewing process. These enzymes potentially hydrolyze starch, proteins and cell wall non-starch polysaccharides including beta-glucan and arabinoxylan. Commercial malts (94) were assayed for the DP enzymes (limit dextrinase, beta/alpha-amylase), and NSP hydrolyzing enzymes (beta-glucanase, xylanase, arabinofuranosidase, beta-glucosidase). The levels of enzyme activity were related to conventional measures of malt quality such as extract, fermentability, protein, KI, DP, friability, wort viscosity, FAN, and beta-glucan. These parameters were interrelated with less conventional measures of malt quality including coarse extract and fermentability (modified infusion mash 65 degrees C), lautering efficiency, the Small-scale Wort 'I' Filtration Test (SWIFT), and viscosity. Substantial variation was observed between the malt samples for all enzymes assayed. Australian barley, whether malted in Australia (n = 61) or China (n = 24), was observed to be of comparable quality. A limited set of Canadian barley samples (n = 9) were malted in China and produced malts with somewhat higher levels of extract, AAL, and some enzymes. Remarkably, the level of limit dextrinase was observed to be almost double that from previous investigations. Greater levels of steep water aeration were proposed to explain this dramatic increase. The interrelationships between the enzyme activities and malt quality identified, enable potential selection of novel malt quality parameters that are more predictive of a malt's brewing performance (efficiency and quality) than current measures to provide a malt quality assessment system based on 'functional' malt quality.

This investigation presents a holistic and comprehensive assessment of the stepwise changes in barley quality during the malting process for multiple batches of two Australian malting varieties (Buloke and Gairdner), in two modern, commercial scale pneumatic malthouses. The study sought to analyse and compare malting plant and variety with respect to basic changes in malt quality for protein (total protein and free amino nitrogen), fermentability (apparent attenuation limit and diastatic power), extract yield, along with filtration indicators (lautering efficiency, viscosity and beta -glucan). Overall, comparing the two malt plants, it was observed that although malt batches and varieties followed different malting pathways, the finished and kilned malt was of satisfactory quality in terms of FAN, viscosity, friability, fermentability and extract. (c) 2020 The Institute of Brewing & Distilling

Colourimetric assays were used to measure the activities of six key hydrolases endogenous to barley: beta-glucanase, xylanase, cellulase, alpha-amylase, beta-amylase and limit dextrinase. The analysed barley malt samples were previously characterised by 27 conventional malt quality descriptors. Correlations between enzymatic activities and brewing parameters such as extract yield, fermentability, viscosity and filterability were investigated. A single extraction protocol for all six hydrolases was optimised and used for multi-enzyme analysis using fully automatable assay formats. A regression analysis between malt parameters was undertaken to produce a relationship matrix linking enzyme activities and conventional malt quality descriptors. This regression analysis was used to inform a multi-linear regression approach to create predictive models for extract yield, apparent attenuation limit, viscosity and filterability using the Small-scale Wort rapid Filtration Test (SWIFT) and two different mashing protocols - Congress and a modified infusion mash at 65 degrees C (MIM 65 degrees C). It was observed that malt enzyme activities displayed significant correlations with the analysed brewing parameters. Both starch hydrolases and cell wall hydrolase activities together with modification parameters (i.e. Kolbach index) were found to be highly correlated with extract yield and apparent attenuation limit. Interestingly, it was observed that xylanase activity in malts was an important predictor for wort viscosity and filterability. It is envisaged that the automatable measurement of enzyme activity could find use in plant breeding progeny selection and for routine assessment of the functional brewing performance of malt batches. This analytical approach would also contribute to brewing process consistency, product quality and reduced processing times. (C) 2019 The Institute of Brewing & Distilling

Stages of the brewing process, such as mash separation to produce wort and beer filtration, can in certain cases prove problematic due to the increased viscosity caused by high levels of the non-starch polysaccharides, primarily beta-glucan and arabinoxylan. Of these two polysaccharides, beta-glucan has been extensively studied, but arabinoxylan has been somewhat overlooked. The concentration of arabinoxylan present during these process stages is principally expected to be inversely related to the malt endo-1,4-beta-xylansase activity that is available to degrade these polysaccharides. The development of a novel method for the measurement of endo-1,4-beta-xylansase activity in barley malt extracts is described herein. The method was characterised by two analysts in terms of repeatability (single analyst CVs = 2.2% and 2.3%, n = 8; interanalyst CV = 4.8%, n = 16) and sensitivity (LOD = 10 U/kg, LOQ = 34 U/kg). The assay procedure was then applied to the measurement of xylanase activity in a series of eight standard barley malts and the results obtained were compared with their associated Congress wort viscosities as measured using the conventional EBC Method 4.8, wort viscosity. A highly statistically significant relationship between xylanase activity and wort viscosity was found with a Pearson's correlation coefficient of -0.82 (p-value of 0.007).

The extent and type of microbial growth on barley grain is a key determinant of malt quality for beer production, as problematic microbial products can persist into the brewing process and impact beer quality. Microbial composition on malting barley grain are influenced by field growth, storage and malting conditions. The present study investigated the efficacy of electrolysed water (EW) with free chlorine concentrations of 5, 50, 100 and 500 ppm, as well as peroxyacetic acid (PAA) at 100 and 500 ppm, as pre-steep treatments to control microbes on grains during the malting process. The research determined the reduction in the load of Pseudomonas spp., heterotrophic bacteria, yeasts and filamentous fungi on weathered and on non-weathered grains. Pseudomonas spp., heterotrophic bacteria and yeasts were significantly reduced up to 4 logs when treated with 500 ppm PAA. PAA reduced filamentous fungi but 500 ppm free chlorine EW showed greater reductions. None of the treatments had detrimental effect on grain germination. The variation in antimicrobial efficacy among treatments can be attributed to variations in microbial susceptibility as well as differences in anti-microbial mechanisms specific to each antimicrobial agent.

Two Australian (Buloke and Commander) and two Canadian (CDC Meredith and Bentley) barley varieties were grown under four levels of nitrogen fertilization (0, 20, 40 and 80kg ha(-1)). Barley samples were assessed by barley brewing with the Ondea Pro enzyme cocktail for mashing analysis and were compared with typical malt brewing quality specifications. The study observed that increased nitrogen fertilization resulted in increased barley kernel nitrogen content which significantly impacted a range of wort quality parameters including increased soluble nitrogen, free amino nitrogen and barley beta-amylase level, but also reduced extract, barley Kolbach index, -glucan and colour. Increased grain nitrogen had relatively little effect on apparent attenuation limit, lautering and barley limit dextrinase level. Knowledge of the effects of interactions between barley of different qualities (e.g. nitrogen content) and the Ondea Pro enzymes on wort quality will result in enhanced barley to directly and efficiently brew good quality beer, to better satisfy the quality expectations of brewers. Copyright (C) 2018 The Institute of Brewing & Distilling

A key biochemical process in brewing is the hydrolysis of starch by diastatic power (DP) enzymes into fermentable sugars during the mashing stage of brewing. Efficient starch hydrolysis during mashing requires initially starch gelatinization at approximately 59–64°C and then sufficient DP enzyme activity to achieve starch hydrolysis. This investigation compared the persistence of DP enzyme activity during modified Institute of Brewing (MIoB, 1:3 grist/water ratio + Ca2+) mash with the conventional Congress (1:4 grist/water ratio) small-scale mash, using malt from three current Australian barley varieties. Traditionally, with the thermostability of DP enzymes, it is understood that α-amylase is relatively thermostable, whereas β-amylase and limit dextrinase (LD) are relatively thermolabile at conventional mashing temperatures. In addition, it is also known that β-amylase and in particular LD have bound and latent fractions that require release from binding proteins or inhibitors, respectively, before they are able to contribute to starch hydrolysis. One mechanism observed empirically was that heat applied during mashing at temperatures of approximately 55–60°C appears to liberate bound β-amylase and LD. The results in terms of DP enzyme release, thermostability, and activity were examined to understand the relative contributions of the three key DP enzymes to starch hydrolysis during different mashing conditions. Interestingly, we observed that both β-amylase and LD retained significant levels of activity (approximately 40% total activity), even after mashing for 60 min at 65°C. These observations are of critical importance to brewers in meeting beer quality specifications when they manipulate mash temperatures to cope with variations in malt quality, developing new products, or producing beers requiring different wort qualities for production. The implications from these results of the choice of small-scale mash protocol for malt quality evaluation, the targeting of DP enzyme alleles for barley malt quality improvement, and the selection of malt for brewing are discussed.

Malt is a preferred base for fermentations that produce beer or whisky. Barley for malt is grown under diverse environments in different geographical locations. Malt provides an ecological niche for a varied range of microorganisms with both positive and negative effects on its quality for brewing. Little information exists in the literature on the microbial community structure of Australian malt as well as broader global geographical differences in the associated fungal and bacterial communities. The aims of the present study were to compare the bacterial and fungal community structures of Australian commercial malt with its international counterparts originating from different geographical regions using terminal restriction fragment length polymorphism (TRFLP) fingerprinting and clone library analyses of ribosomal RNA genes. Further, the relationship between malt associated microbial communities and conventional malt quality parameters was also compared. Results showed that differences in fungal communities of malts from different geographical location were more pronounced than bacterial communities. TRFLP analysis discriminated high quality commercial malts with low fungal loads from malts deliberately infected with fungal inocula (Fusarium/Penicillium). Malt moisture, beta-amylase, α-amylase and limit dextrinase contents showed significant correlations with fungal community structure. This investigation concluded that fungal community structure was more important to subsequent malt quality outcomes than bacteria.

The fermentable carbohydrate composition of wort has a direct influence on yeast fermentation efficiency and resultant beer quality. In this study, the relationship between diastatic power enzymes (DPE) and their wort sugars products during the course of small-scale, emulated commercial mashing was investigated. Malts derived from 13 barley cultivars were mashed and assayed at five time points during mashing for the levels of DPE and fermentable sugars. Comparisons of the patterns of DPE activity and wort sugar production showed that the activity levels of beta-amylase and limit dextrinase (LD) during mashing were variable between the 13 cultivars, in comparison to the level of a-amylase and resultant composition of wort sugars. Moreover, comparison of peak DPE activities indicated that alpha-amylase correlated positively and significantly with LD, while no obvious correlation was found between beta-amylase and either alpha-amylase or LD, indicating that activity pattern of alpha-amylase and LD was closely related during mashing. Multiple linear regression models, based on levels of the DPE as various time points during mashing, thermostability of beta-amylase and malt Kolbach index, were able to explain 42.9%, 91.9%, 94%, and 73.2% of wort maltotriose, maltose, glucose, and fermentable sugar composition, respectively. A combination of these insights into the dynamics of starch hydrolysis during mashing will assist brewers in malt cultivar selection and the adjustment of mashing conditions so as optimize the sugar content for the efficient production of high quality beer.

The impact of malt blending on brewing performance in terms of extract, lautering, and fermentability performance was examined in a series of small-scale mashing trials. Malts were blended so that 40–60% of the grist consisted of malt with lower levels of one or more of these malt quality characteristics. With extract, blending resulted in additive improvements between malts of lower and higher levels. In contrast, improvements were synergistic for lautering performance when there was a substantial difference between the lautering performance of the two malts. The markers for synergism in lautering performance were the level of β-glucanase and wort viscosity. Fermentability performance also typically showed synergism between low and high fermentability malts, with the exception of one malt sample whose blend combination showed an unexplained antagonism. The synergism in fermentability performance was achieved when there was a deficiency between the malts for Kolbach index, the diastatic power enzymes, or β-amylase thermostability that compensated for the lack of these components in the lower-fermentability malts. The importance of these blending interactions was discussed in relation to malt quality specifications and achieving consistent and predictable brewing outcomes.

Premature yeast flocculation (PYF) is a sporadic fermentation problem in the brewing industry that results in incomplete yeast utilization of fermentable sugars in wort. Culture-independent, PCR-based fingerprinting techniques were applied in this study to identify the associations between the occurrence of the PYF problem during brewery fermentation with barley malt-associated microbial communities (both bacteria and fungi). Striking differences in the microbial DNA fingerprint patterns for fungi between PYF positive (PYF +ve) and negative (PYF −ve) barley malts were observed using the terminal restriction fragment length polymorphism (TRFLP) technique. The presence of terminal restriction fragments (TRFs) of 360–460 bp size range, for fungal HaeIII restriction enzyme-derived TRFLP profiles appeared to vary substantially between PYF +ve and PYF −ve samples. The source of the barley malt did not influence the fungal taxa implicated in PYF. TRFLP analysis indicates bacterial taxa are unlikely to be important in causing PYF. Virtual digestion of fungal sequences tentatively linked HaeIII TRFs in the 360–460 bp size range to a diverse range of yeast/yeast-like species. Findings from this study suggest that direct monitoring of barley malt samples using molecular methods could potentially be an efficient and viable alternative for monitoring PYF during brewery fermentations.

The impact of malt blending on brewing performance in terms of extract, lautering, and fermentability performance was examined in a series of small-scale mashing trials. Malts were blended so that 40–60% of the grist consisted of malt with lower levels of one or more of these malt quality characteristics. With extract, blending resulted in additive improvements between malts of lower and higher levels. In contrast, improvements were synergistic for lautering performance when there was a substantial difference between the lautering performance of the two malts. The markers for synergism in lautering performance were the level of â-glucanase and wort viscosity. Fermentability performance also typically showed synergism between low and high fermentability malts, with the exception of one malt sample whose blend combination showed an unexplained antagonism. The synergism in fermentability performance was achieved when there was a deficiency between the malts for Kolbach index, the diastatic power enzymes, or â-amylase thermostability that compensated for the lack of these components in the lower-fermentability malts. The importance of these blending interactions was discussed in relation to malt quality specifications and achieving consistent and predictable brewing outcomes.

A survey of the preferences of brewing professionals with respect to beer presentation and amount of beer foam was conducted at the ASBC Brewing Summit meeting in Providence, Rhode Island, in 2010. The survey showed that beer presentation in the Samuel Adams Boston Lager Perfect Pint glass was not only aesthetically pleasing but also promoted hop aroma and flavors in particular. Most of the survey participants preferred the presence of lacing on the glass during or after consumption and, on average, considered approx. 20 mm of foam immediately after dispensing into a glass as being optimal. The conventional NIBEM and Rudin methods for foam stability testing were compared with a simple method of manually pouring a beer into a Perfect Pint glass (approx. 35 mm of foam formed) and visually scoring the stability after 5 min to determine the foam stability score (FSS). The NIBEM and Rudin foam stability measures were significantly but relatively poorly correlated (r = 0.371). In part, this relatively poor correlation resulted from a wide range of beer viscosity in the sample set that inordinately influenced the Rudin results. In general, the NIBEM and Rudin foam stability measures were significantly correlated with bitterness, beer-foam-promoting proteins measured as Coomassie blue binding protein assay, beer color, alcohol, CO2 content, and pH, which was broadly consistent with previous studies. Although lipids are widely acknowledged as foam damaging, the measurement of total fatty acids (a lipid proxy) was not well correlated with either of the foam stability analysis methods. The FSS was significantly correlated to and largely predicted by CO2 content and beer-foam-promoting protein levels. These insights are discussed in relation to how brewers could design and consistently provide beers to customers that fulfill their foam quality requirements and expectations.

Micro plate readers are ideal for high throughput liquid assays for a variety of scientific and industrial applications. They provide versatile spectrophotometric detection systems with opportunities for developing a wide range of chemical and biochemical test methods. The microplate 8 x12 well format enables "semi-automated" sample and reagent handling that is particularly suitable for efficient analysis of large numbers of samples. Thus analysis times are rapid, with low reagent volumes saving on reagent costs and waste disposal charges. The malting industry is well placed to exploit micro-plate technology for tests such as wort colour, β-glucan, free amino nitrogen (FAN) and soluble nitrogen as well as malt enzyme activity. Testing for multiple enzyme activities, such as those involved in barley starch degradation (DP enzymes), has been made more efficient using micro plates, improving the scope for malt fermentability prediction. Rapid “in-process” testing prior to malt kilning is also possible for the measurement of soluble protein and β-glucan in the malting plant. This project focussed initially on the application of micro plate readers for ß-glucan and FAN determination in malt extracts. The results of the wort β-glucan testing showed reasonable agreement with segmented flow injection analysis over a range of β-glucan concentrations. Analysis costs for ß-glucan testing was reduced and training and maintenance requirements were simplified using micro plate readers. Green malt extracts were also investigated using micro plates for following the progress of malt modification prior to kilning.

The objective of this study was to comprehensively and methodically evaluate the small-scale mash parameters of the standard Congress (EBC and ASBC) mash protocol in order to modernize this protocol so it better emulates modern commercial brewing practices. For the recommended final 65°C mash protocol, the key parameters were grist milling at 0.7 mm by disc mill, an initial grist/water ratio of 1:3, an initial mash temperature of 65°C, and an initial mashing phase of 65°C for 60 min. Of lesser importance, but still adopted due to widespread use in commercial brewing, was the addition of CaSO4 (0.3 mM) and completion of mashing at 74°C, after which the grist/water ratio was decreased to 1:6 before cooling and lautering. The “final 65°C” mash protocol was compared with the Congress mash protocol and a simple 65°C variant (“old 65°C”) mash protocol to determine the influence of mash protocol on extract and fermentability using a selection of 29 commercial malts. It was demonstrated that the choice of mash protocol applied had subtle, but important, impacts on the determination of extract and prediction of fermentability. Through a relatively simple modification of the small-scale wort production protocol, measurement of malt lautering performance, based on the volume of wort lautered at 25 min, was also proposed. The investigation showed that the mash protocol used could interact with subtle differences in malt characteristics, which could alter the relative importance of the predictive parameters of important malt quality characteristics such as extract, fermentability, and lautering. Researchers and malt quality technicians should be aware that these subtle influences could potentially result in unexpected biases in routine malt analyses and research investigations of components that influence malting and brewing parameters.

J. Inst. Brew. 117(3), 335-342, 2011Influences on foam stability and cling were compared by brewing trials investigating beer hopping rate, hopping type and modification of beer protein composition by the inclusion of a proline specific protease (PSEP). The comparison of the NIBEM, Rudin and lacing foam assessment methods with the level of hopping demonstrated the superiority of hydrogenated hop alpha-acids with respect to foam stability and particularly lacing. In addition, the NIBEM and Rudin foam analysis tests appear to respond relatively similarly with respect to hopping rate and hop type, with the NIBEM being somewhat more responsive in terms of foam stability measurments. The PSEP trials suggested that protein composition may only have a subtle effect on foam stability. Although more specific to haze active proteins, PSEP treatment in the small and pilot scale trials generally, but not always, resulted in a minor reduction in foam stability. This effect was not observed in 20 hL pilot and industrial scale beer productions. It was verified that both NIBEM and Rudin were positively influenced by increased levels of foam positive proteins. Although both foam tests were responsive to hopping rate and type, it is suggested that the Rudin foam test is somewhat biased towards foam positive proteins, particularly albuminous foam positive proteins (LTP1 and protein Z4), while in comparison the NIBEM foam test appears somewhat biased towards hordein foam positive proteins.