Influence of High Protein Digestibility Sorghums on Free Amino Nitrogen (FAN) Production during Malting and Mashing

In sorghum brewing, obtaining sufficient Free Amino Nitrogen (FAN) for rapid and complete fermentation remains a problem due to the high proportions of unmalted sorghum used and the poor digestibility of wet‐heat treated sorghum protein. Sorghum mutant lines with high protein digestibility have been developed through breeding. These high protein digestibility sorghums (HPDS) have protein bodies with villi‐like borders that apparently facilitate protease access. This work investigated FAN production from HPDS when malted and mashed, to assess their potential for use in sorghum brewing to improve wort FAN levels. When malted, HPDS contained substantially higher levels of FAN than normal protein digestibility sorghums (NPDS), 32 mg/100 g malt more. However, when the HPDS were mashed either as malt, or as grain or malt plus exogenous proteases, FAN production during mashing was not substantially higher than with NPDS subjected to the same treatments, only 6, 6–18 and 9–13 mg/100 g grain or malt, respectively. This is probably due to wet‐heat induced cross‐linking of the kafirin proteins reducing their susceptibility to proteolysis. Notwithstanding this, HPDS could be very useful for improving FAN levels in sorghum brewing if they are malted.     

Current Developments in Malting and Brewing Trials with Sorghum in Nigeria: A Review

Initially, large‐scale lager beer brewing with sorghum malts proved highly intractable due to a number of biochemical problems including: high malting losses estimated at 10–30% as against 8–10% for barley; high gelatinisation temperatures which limited starch solubilisation/ hydrolysis by the amylolytic enzymes during mashing; low extract yield/low diastatic power (DP) due to inadequate hydrolytic enzyme activities especially β‐amylase; low free α‐amino nitrogen (FAN) due to inadequate proteolysis limiting yeast growth during fermentation; high wort viscosities/beer filtration problems due to low endo‐β‐1,3; 1–4‐glucanase activities on the endosperm cell walls causing the release of some β‐glucans. Strident research efforts using improved Nigerian sorghum malt varieties (SK5912, KSV8 and ICSV400) have reported some encouraging results. The knowledge of the biochemical integrity of the endo‐β‐glucanases of the sorghum malt is helping to elucidate their mode of activity in the depolymerisation of the β‐glucans. This is bound to ensure process efficiency in sorghum beer brewing, reduce beer production costs and ultimately, produce a Pilsner‐type of lager beer with 100% sorghum malt.     

Free α-amino nitrogen production in sorghum beer mashing

Free α-amino nitrogen (FAN) is an essential nutrient for yeast growth during fermentation. Under normal conditions of sorghum beer mashing, 60°C at pH 4.0, production of FAN by proteolysis accounts for approximately 30% of wort FAN, the remaining 70% being preformed in the malt and adjunct. The quality of the FAN in sorghum beer worts is good as it does not contain a high percentage of proline. Optimum conditions for FAN production during mashing are 51°C and pH 4.6. Wort FAN was increased proportionally by raising the ratio of sorghum malt to adjunct and conversely decreased by raising the ratio of adjunct to malt. FAN was also increased by the addition to the mash of a microbial proteolytic enzyme. Wort FAN is directly proportional to malt FAN.     

125th Anniversary Review: The science of the tropical cereals sorghum,maize and rice in relation to lager beer brewing

Mainstream lager beer brewing using the tropical cereals sorghum, maize and rice, either as malt or as raw grain plus commercial enzymes, is becoming widespread. This review examines the differences in composition between these tropical cereals and barley and their impact on brewing processes and beer quality. All of these cereals have a starch gelatinization temperature some 10 °C higher than barley. The sorghum prolamin proteins are particularly resistant to proteolysis owing to disulphide cross‐linking involving γ‐kafirin. Unlike barley, the major endosperm cell wall components in sorghum and maize are arabinoxylans, which persist during malting. The rice cell walls also seem to contain pectic substances. Notably, certain sorghum varieties, the tannin‐type sorghums, contain considerable levels of condensed tannins (proanthocyanidins), which can substantially inhibit amylases, and probably also other brewing enzymes. Tropical cereal malts exhibit a similar complement of enzymic activities to barley malt, with the notable exception of β‐amylase, which is much lower and essentially is absent in their raw grain. Concerning beer flavour, it is probable that condensed tannins, where present in sorghum, could contribute to bitterness and astringency. The compound 2‐acetyl‐1‐pyrroline, responsible for the popcorn aroma of maize and also the major aroma compound in rice, presumably affects beer flavour. However, much more research is needed into tropical cereals and beer flavour. Other future directions should include improving hydrolysis of prolamins into free amino nitrogen, possibly using prolyl carboxypeptidases and investigating tropical cereal lines with useful novel traits such as high amylopectin, high protein digestibility and low phytate. Copyright © 2013 The Institute of Brewing & Distilling     

Effects of phenolics in sorghum grain on its bitterness,astringency and other sensory properties

Despite the fact that condensed tannins are potentially important antioxidants, there is a general belief that tannins in sorghum confer objectionable sensory attributes. The objective of this study was to determine differences in the sensory attributes of sorghums containing different levels of total phenolic compounds. A trained sensory panel described and quantified the sensory attributes of different sorghums (condensed‐tannin containing and tannin‐free). All the sorghum cultivars were perceived as bitter and astringent. Bran infusions of tannin sorghums were perceived as darker, clearer, more bitter and more astringent than those of the tannin‐free sorghums, while those of tannin‐free sorghums were perceived as sweeter and cloudy. Sorghum whole‐grain rice from the tannin sorghums which had relatively soft endosperm texture (PAN 3860 and Ex Nola 97 GH) was perceived as dark, hard, chewy, bitter and astringent, while that from tannin‐free sorghums having relatively hard endosperm texture (Segaolane and Phofu) was perceived as soft, sweet and had a maize‐flavour. Surprisingly, the bitterness and astringency, as well as other sensory attributes of NS 5511 (tannin sorghum), were perceived as similar to PAN 8564 (tannin‐free sorghum) even though NS 5511 had more than twice the total phenol content of PAN 8564. This suggests not all condensed‐tannin containing sorghums have objectionable sensory attributes. Copyright © 2007 Society of Chemical Industry     

Unmalted triticale cultivars as brewing adjuncts: effects of enzyme activities and composition on beer wort quality

The applicability of three selected triticale cultivars (Trinidad, Lamberto, Fidelio) for use as brewing adjuncts was investigated in comparison with wheat adjunct and barley malt. Fermentable substance, crude protein and arabinoxylan levels of starchy materials were determined as well as their native potencies (amylolytic, proteolytic, pentosolytic) to solubilise and degrade grain components during mashing. Laboratory‐scale experiments were performed to evaluate the influence of the adjuncts (composition, enzyme potency) on beer wort quality by mashing mixed (1:1) grists of malt and adjunct. Barley malt was rated as the superior raw material, possessing considerably higher enzyme activities and yielding the lowest wort viscosity. Among the triticale cultivars cv Trinidad was identified as the most suitable to serve as a brewing adjunct due to its improved starch solubilisation properties and its ability to generate low wort viscosities. Compared with the potent malt enzymes, the enzyme activities of unmalted triticale (such as amylases, pentosanases and proteases) had little affect on the composition of the sweet worts. In contrast, the contents of crude protein and fermentable substance of the triticale varieties greatly affected wort quality. Furthermore, the adjunct moiety determined the level of wort viscosity when mashing a combination of malt and triticale. In general, the brewing properties of triticale cv Trinidad were comparable with those of wheat. Copyright © 2004 Society of Chemical Industry     

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     

Polyphenol oxidase activity in white tan‐plant‐type sorghums: An important determinant of the relatively dark colour of their porridges

The relatively dark colour of food products from white tan‐plant (food‐grade) sorghums can compromise their acceptability. The relationship between white tan‐plant sorghum polyphenol oxidase activity (PPO) and porridge colour was investigated, primarily using lines grown in the same locality over two seasons. Sorghum was intermediate in PPO between wheat and maize. White tan‐plant sorghum and white maize whole grain flours were similar in colour. However, with white tan‐plant sorghum, the transition from flour to porridge caused a much larger reduction in L* value. Further, the correlation between white tan‐plant sorghum PPO activity and porridge L* values was highly significantly negative (P < 0.001), the relationship accounting for 40–50% of variation. PPO in white tan‐plant‐type sorghums is therefore an important determinant of the relatively dark colour of porridges. Breeding to reduce PPO activity could improve consumer appeal. Cultivar Sima (IS 23520) that had low PPO activity and produced light‐coloured porridge could be useful for breeding.     

Effect of mashing procedures on brewing

The effect of the double decoction mashing method (method A) and the single decoction plus infusion mashing method (method B) on brewing were compared. The trials were carried out with the same raw material (malt and a minor amount of corn as adjunct) on an industrial-scale plant. The effects of mashing methods A and B were evaluated in wort and beer samples obtained with the high gravity system. The analytical parameters of the worts and beers produced and the economic aspects of production (yield, beer quality, time and energy) were discussed. The results showed no considerable differences in beer quality, while a significant difference was observed in the composition of fermentable sugars of worts. Method B gave a wort with a higher content of fermentable sugars which were converted to alcohol during fermentation; therefore, it allowed to obtain a higher beer volumetric yield of the same quality while saving time and energy.     

Investigation of mashing regimes for low‐alcohol beer production

Low‐alcohol beer can be obtained by physical and biological methods. The group of biological methods includes modification of the mashing regimes and changes in the fermentation process. The aim of the present work was to study two mashing regimes for low‐alcohol beer production. The increase in the mashing duration at 50 °C led to a linear increase in the extract and the concentration of reducing and fermentable sugars in the wort. It was found that the rate of formation of reducing sugars was higher than that of the formation of fermentable sugars, which can be used for the optimization of the mashing process. The introduction of a pause at 77 °C did not lead to a substantial increase in the concentration of fermentable extract, but did lead to an increase in the total and non‐fermentable extract. The available nitrogen content in the laboratory wort was in the range of 120–150 mg/dm³. As a result of conducting fermentation processes with the top‐fermenting yeast strain Saccharomyces cerevisiae S‐33, it was found that the combination of a small amount of fermentable sugars and a low fermentation temperature led to a beer being obtained that met the requirements for a low‐alcohol beverage. Copyright © 2016 The Institute of Brewing & Distilling     

Potential for improvement in yeast nutrition in raw whole grain sorghum and maize lager brewing and bioethanol production through grain genetic modification and phytase treatment

Brewing and bioethanol production with raw grain and exogenous enzymes produces wort with satisfactory hot water extract (HWE). However, the free amino nitrogen (FAN) and mineral content can be too low, owing to low protein digestibility (PD) and phytate–mineral chelation, respectively. This study evaluated the potential for improvement in yeast nutrition in raw whole sorghum and maize brewing and bioethanol production by genetic modification (GM) of sorghum to improve PD and reduce phytate content, and by treatment with exogenous phytase. While phytase addition decreased sorghum spent grain phytate content (88%) and content of minerals (17 to 59%; i.e. increased wort mineral content), it did not affect maize phytate spent grain mineral content or HWE significantly. However, phytase addition did increase maize wort FAN (20%), sorghum HWE (2.8 percentage points) and wort FAN (23%). GM sorghum gave reduced spent grain mineral contents (11–38%), increased HWE (5.5 percentage points) and wort FAN (71%). Hence, genetic modification of sorghum to improve PD and reduce phytate content has considerable potential in raw grain brewing and bioethanol production to improve yeast nutrition. Copyright © 2012 The Institute of Brewing & Distilling     

THE INFLUENCE OF FREE ALPHA-AMINO NITROGEN IN SORGHUM BEER FERMENTATIONS

The interactions of wort free α-amino nitrogen (FAN) and sugar in sorghum beer fermentations were quantified and a simple equation derived. This equation describes the wort FAN demand as a function of the sugar concentration necessary to produce a fully fermented beer within 48 hours. The influence of wort FAN on sorghum beer fermentations had not been quantified so research was undertaken to define sorghum beer yeasts' requirement for wort FAN and the interactions that occur between wort FAN and sugar. Laboratory, sorghum malt and adjunct, worts mashed to cover a wide range of FAN and wort sugar concentrations, were fermented and analysed. The initial wort FAN affects the ethanol production rate, FAN uptake and sugar utilisation rates.     

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     

酿酒高粱籽粒微观形态分析及其果皮厚度和单宁含量的相关性

该研究对全国已推广的19份酿酒高粱的果皮（果皮层和种皮层）厚度及淀粉粒径长度进行统计分析,并初步总结了高粱籽粒单宁含量与果皮厚度间的关系。结果表明,酿酒高粱的果皮厚度并不呈单峰分布,西南糯高粱的果皮厚度与其他地区高粱差异显著（P＜0.05）,其中红缨子高粱果皮厚度在＜100 μm范围内平均值为（59.74±9.87） μm。不同酿酒高粱淀粉粒径长度差异也比较明显,说明高粱原料酿造性状的优劣要综合考虑其性状表现。单宁含量和果皮厚度间具有较好的直线相关关系（R=0.501 4）,果皮厚度每增加1 μm,籽粒的单宁含量则增高0.014 7%。     

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.     

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     

Effect of Germination Moisture and Time on Pearl Millet Malt Quality — With Respect to Its Opaque and Lager Beer Brewing Potential

The effect of germination moisture and time on pearl millet malt quality was investigated. Two pearl millet varieties SDMV 89004 and 91018 were germinated at 25°C under three different watering regimes for 5 days. As with sorghum malting, diastatic power, beta‐amylase activity, free α‐amino nitrogen (FAN), hot water extract and malting loss all increased with level of watering. However, pearl millet malt had a much higher level of beta‐amylase and higher FAN than sorghum malt and a similar level of extract. Malting losses were similar or lower than with sorghum. Thus, it appears that pearl millet malt has perhaps even better potential than sorghum malt in lager beer brewing, at least as a barley malt extender, especially in areas where these grains are cultivated and barley cannot be economically cultivated. Also, its increased use in commercial opaque beer brewing, where sorghum malt is currently used, could be beneficial.     

A novel approach for the production of a non‐alcohol beer (≤0.5% abv) by a combination of limited fermentation and vacuum distillation

Despite the increasing demand, the production of non‐alcohol beers is still limited by unsatisfactory or artificial flavour and taste. In this study, a novel approach to producing non‐alcohol beer is presented, in which the alcohol‐reducing techniques, limited fermentation and vacuum distillation were combined. Starting from barley and wheat malts, wort with a low level of fermentable sugars was prepared by infusion mashing and lautering. Limited fermentation was carried out by Saccharomycodes ludwigii at 18°C. When the level of fermentable sugar was reduced by 25%, the fermented wort was quickly cooled from 18 to 0°C and held at that temperature for two days. The young beer was obtained after degassing and removal of yeast and was then subjected to vacuum distillation at 0.06 MPa to remove the alcohol. The concentrated extract is suitable for storage and transportation. The final product of non‐alcohol beer was obtained by dilution with deoxygenated water and carbonation with 6.0 g/L CO₂, followed by addition of 8–12% of regular beer and equilibration for 2–3 days to develop normal beer aroma. The results showed that the non‐alcohol beer had several favourable properties, including the alcohol level of <0.5% (v /v), colour 7.0 (EBC), thiobarbituric acid value of 1.05 and ratio of alcohols to esters of 1.08. Compared with other methods for the production of non‐alcohol beer, this novel approach produced a favourable alternative to regular beers with similar flavour characteristics and satisfactory stability. Copyright © 2017 The Institute of Brewing & Distilling     

低浓度淡爽型啤酒的酿造

以改善低浓度淡爽型啤酒品质为目的 ,提出了一种新颖的低浓度淡爽型啤酒的酿造方法 .采用二次煮出二段式糖化法 ,用 70 %麦芽和 3 0 %大米的原料配比 ,提高麦芽汁中糖与非糖的比值 ,并在糖化过程中添加啤酒酵母提取物作啤酒发酵的补充氮源 .所酿造的啤酒口味纯正 ,泡沫洁白细腻 ,持久挂杯 .     

Brewing with up to 40% unmalted oats (Avena sativa) and sorghum (Sorghum bicolor): a review

Beer production with up to 40% unmalted cereals such as barley, wheat, rice and maize is legally allowed and thus practised in many European countries. The use of oats and sorghum as brewing adjuncts has great potential for creating new beer types/flavours and saving costs. In contrast to oats, sorghum is not as well known within Europe; however, its versatility makes it a very promising crop for exploitation in these temperate‐zone regions. This review describes the brewing‐relevant characteristics of unmalted oat and sorghum grain, investigates the role and properties of endogenous/exogenous enzymes during mashing, discusses the processability/quality of mashes, worts and beers produced with up to 40% oat or sorghum adjunct, and examines the effectiveness/limitations of endogenous enzymes as well as the benefits of the application of exogenous enzymes. Copyright © 2014 The Institute of Brewing & Distilling