ESTIMATION OF CARBOHYDRATES IN WORTS AND BEERS BY GAS CHROMATOGRAPHY

Modifications of existing methods using trimethylsilyl ethers for estimating wort and beer carbohydrates are described. Samples to which a known amount of phenyl β-D-glucopyranoside is added as internal standard are quickly dried in vacuo at 40° C. prior to trimethylsilylation and chromatography. Peak areas of separated sugars are measured relative to the standard and are computed as the concentrations present in the original samples by way of calibration factors, obtained by similar treatment of known amounts of pure sugars. Standard deviations of less than 5% are obtained for glucose, maltose and maltotriose from twelve replicate analyses of a given wort. The technique, applied to a number of worts and beers of varied composition, compares favourably with existing methods of estimating individual sugars in worts and beers.     

Changes in the carbohydrate constituents of yam tuber (dioscorea rotundata,poir) during growth

The amounts of sugars, starch, hemicellulose and cellulose in yam tubers were estimated at different stages of maturity and in yam tuber (“EgbodO”) sections. Maltose, sucrose, glucose and fructose were the free sugars identified in the ethanolic extracts of the yam samples. Sucrose formed the bulk of the total sugars. The “bottom” portion of the “Egbodo” yam tuber was richer in total sugars (4.9%) than either the “middle” (1.8%) or the “head” (2.4%) regions. Starch accounted, respectively, for 60, 77 and 78% of total carbohydrates in the “bottom”, “middle” and “head” regions of the “egbodo” yam tuber. A peak value of 84% starch was obtained 6 months after planting the yam setts. Its decrease to 64% at 8 months has been partly attributed to reduced photosynthetic activity through yellowing and subsequent loss of leaves. The sum of cellulose and hemicellulose, regarded as non-available carbohydrates was less than 7% of the total carbohydrates. The linear fraction, amylose, formed about 17.8% of the starch prepared from whole yam tubers of varying maturities, and from yam tuber sections, the remaining being amylopectin. The observed amylose and amylopectin values did not vary significantly over the period of observation. These amylose and amylopectin fractions had iodine affinities of 17 and 0.1%, respectively.     

Carbohydrate content and structure during malting and brewing: a mass balance study

A holistic view of the fate of barley starch, arabinoxylan and β-glucan throughout malting and brewing is largely missing. Here, an industrial scale malting trial and pilot brewing trial were performed, and the concentration and structural characteristics of carbohydrates were analysed at 28 key points in the process. The barley starch content decreased during malting from 75.0% to 69.7%. During mashing, malt starch was converted to fermentable sugars (75.3%), dextrin (22.8%) or was retained in spent grains (1.8%). Arabinoxylan was partially hydrolysed during malting. Despite mashing-in at 45°C, no further solubilisation of arabinoxylan was observed during mashing. However, the average degree of polymerisation of the soluble arabinoxylan fraction decreased slightly. During fermentation, the arabinoxylan content decreased to 2.5 g/L. The amount of barley β-glucan decreased gradually in time during malting. Of the solubilised β-glucan, 31% was retained in the spent grains during wort filtration, slightly lowering the β-glucan content in the wort. The β-glucan content remained at 0.5 g/L during fermentation. Sucrose was hydrolysed during mashing, probably by barley invertases. From the total amount of malt used, 41.0% was converted to fermentable sugars. This mashing yield could have been improved by the full hydrolysis to fermentable sugars of the present β-glucan (to 41.1%), the remaining starch in spent grains (to 42.0%) and dextrin in wort (to 50.3%). These results provide more insight into the carbohydrate conversions during malting and brewing and can act as a baseline measurement for future work. © 2020 The Institute of Brewing & Distilling     

GAS LIQUID CHROMATOGRAPHY OF WORT AND BEER CARBOHYDRATES II. QUANTITATIVE DETERMINATION OF WORT,BEER, AND BREWING SYRUP CARBOHYDRATES

A method for the preparation and gas chromatography of the trimethylsilyl derivatives of carbohydrates was applied to the quantitative analysis of carbohydrates in worts, beers, and brewing syrups. The derivatives can be easily and quickly prepared from lyophilized worts or beers and aliquots of the reaction mixtures can be injected directly into the gas chromatograph. Gas chromatographic separations of the mono- to tetra-saccharide fractions were achieved in less than thirty minutes through the use of linear temperature programming. Recoveries of carbohydrates added to wort ranged from 97 to 105%. Quantitative data for replicate wort analyses showed relative standard deviations of from 1·7% for glucose to 5·3% for maltose. The silylation reaction can be applied to the volatilization and subsequent study of a wide variety of compounds occurring in brewing materials.     

The Horace Brown Medal Lecture: Forty Years of Brewing Research

Horace Brown spent fifty years conducting brewing research in Burton‐on‐Trent, Dublin and London. His contributions were remarkable and his focus was to solve practical brewing problems by employing and developing fundamental scientific principles. He studied all aspects of the brewing process including raw materials, wort preparation, fermentation, yeast and beer stability. As a number of previous presenters of the Horace Brown Lecture have discussed Brown's achievements in detail, the focus of this paper is a review of the brewing research that has been conducted by the author and his colleagues during the past forty years. Similar to Horace Brown, fundamental research has been employed to solve brewing problems. Research studies that are discussed in this review paper include reasons for premature flocculation of ale strains resulting in wort underattenuation including mechanisms of co‐flocculation and pure strain flocculation, storage procedures for yeast cultures prior to propagation, studies on the genetic manipulation of brewer's yeast strains with an emphasis on the FLO1 gene, spheroplast fusion and the respiratory deficient (petite) mutation, the uptake and metabolism of wort sugars and amino acids, the influence of wort density on fermentation characteristics and beer flavour and stability, and finally, the contribution that high gravity brewing has on brewing capacity, fermentation efficiency and beer quality and stability.     

ON THE DIFFERING RATES OF FRUCTOSE AND GLUCOSE UTILISATION IN SACCHAROMYCES CEREVISIAE

Fructose is utilised slower than glucose when the two sugars are fermented separately. This phenomenon occurs in a growth promoting medium as well as in brewers wort when using the brewing yeast Saccharomyces cerevisiae. The use of a fructose adjunct in wort at concentrations of 2% w/v and above, may result in residual concentrations of fructose to remain at the end of fermentation and consequently taint the beer with a sweet off-flavour. Glucose and fructose have no effect on maltose utilisation. Thus they do not exert catabolite repression on the maltose membrane transport system in the particular brewing strain of S. cerevisiae under investigation, when fermented in brewers wort.     

外加酶法酿制低糖啤酒糖化工艺的研究

以普鲁兰酶Ｐｒｏｍｏｚｙｍｅ１２０Ｌ为重点，综合分析了外加酶糖化过程中影响麦汁总还原糖量和糖组成的各种因素，如各酶制剂的用量、糖化温度、料水比、物料比及各因素之间的相互作用等，确定了一套最优的糖化工艺方案。所得麦芽汁浸出率高、色度浅、粘度低、还原糖含量高；经过高效液相色谱分析（ＨＰＬＣ）表明，其糖组成合理；经过十天的发酵，发酵度达８２．２％，酒精分为６．４５５％（Ｗ／Ｗ）。     

THE CAMBRIDGE PRIZE LECTURE 1996 FROM FIELD TO FIRKIN: AN INTEGRATED APPROACH TO BEER CLARIFICATION AND QUALITY

A concerted and integrated research programme has considerably enhanced the current understanding of fining agents and their effect on beer clarification and quality. In addition to previously published data, much new information has been presented to help develop this understanding. The numerous complex and often inter-related factors that affect both isinglass and copper fining performance have been discussed both qualitatively and quantitatively. This information has been used to identify the following critical control parameters which will facilitate the optimisation of beer quality and brewing process efficiency : Pre- and post-fining beer temperature beer particle levels and NMP charge wort pH cold wort clarity beer pH pre-filtration beer clarity . The discrete unit operations of the brewing process have been integrated into a single continuous process, where the efficiency of each operation depends on the efficiency of all of the previous operations, and impacts directly on that of all subsequent operations. Using this approach, beer clarity problems can in certain circumstances be traced back to variations in the microflora present on barley in the farmer's field. Thus to truly control beer quality, the brewing process must be considered to start not with mashing or malting, but rather with barley growing, and the process must be managed right through “from field to firkin” .     

ADJUNCTS

Although not essential in brewing, adjuncts are used in most countries and brewing regions and provide benefits in extract cost and beer qualities. Brewing sugars and caramel syrups may be used to adjust wort and beer characteristics with little capital investment. The incorporation of caramel malts can contribute to beer quality and stability. On a world-wide perspective, cereal-based adjuncts are dominant in the brewing of beer, and are the only adjuncts used in the production of Scotch grain whisky and the whiskeys of other countries, and in malt vinegar produced in the United Kingdom. The cost of adjuncts often depends on local availability, the added value of by-products and the utilisation of the maximum amount of starch or sugar from the agricultural source.     

Carbohydrate Make Up of Huskey Barley

The chemical composition of two and six‐row huskey barley grown under Haryana agroclimatic conditions is reported. Two‐row varieties had slightly higher percentage of reducing sugars, sucrose and lignin, whereas protein, proanthocyanidins, starch, neutral detergent fibre (NDF), acid detergent fibre (ADF) and hemicellulose were higher in six‐row barleys. Malting significantly decreased the starch, sucrose and protein contents, while total soluble sugars, reducing sugars and maltose increased. The concommitant decrease in proanthocyanidins level is also desirable when barley is used for malting and brewing purposes. The variety RD2560 emerged to be superior for malting and brewing. The conduction of feeding trials and investigation of physico‐chemical properties of barley starch are suggested.     

MEASUREMENT OF CARBOHYDRATES IN WORT AND BEER—A REVIEW

Methods are reviewed for measuring total wort and beer carbohydrate and carbohydrate fractions, such as dextrins, oligosaccharides, fermentable sugars, β-glucans, total fructose and fructosans, pentose and pentosans. The methods are conveniently classified under the following headings: reductometry, colorimetry, enzymic procedures, automated analyses, paper and column chromatography, thin layer chromatography, gas liquid chromatography and high performance liquid chromatography. Techniques involving chromatography are particularly useful for separating and estimating individual sugars.     

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.     

MEASUREMENT OF FERMENTABLE SUGARS

A method is described in which the fermentable sugars of wort, beer and syrups are rapidly separated as a group from the unfermentable carbohydrates, by desorption from a charcoal-kleselguhr column using 15% ethanol as the eluting agent. This separation procedure may conveniently be combined with an automated redox electrode procedure for carbohydrate determination.     

Improved quantitative ion chromatography of industrial sugars: removal of interfering amino acids

The effect of interfering amino acids on the accurate quantitation of sugars in sugar industry samples, using ion chromatography with integrated pulsed amperometric detection (IC-IPAD), was investigated. Industrial sugar samples included beet syrup, juice and molasses samples. Using sugar and amino acid standard mixtures, and industrial sugar samples, proline was found to co-elute with fructose and serine with sucrose, and both co-elutions were “additive”, which caused both fructose and sucrose to be overestimated. Conversely, the co-elution of arginine with myo-inositol, and glutamine with glucose had a marked “suppressive” effect on sugar quantitation and both myo-inositol and glucose were underestimated. Various methods were investigated for their efficiency to remove interfering amino acids, but not remove sugars: prefiltering of dilute samples through cation exchange syringe filters proved the most efficient method. Using sugar and amino acid standard mixtures, within experimental error, the cation exchange filter restored the mean concentrations of myo-inositol, glucose and sucrose to expected values, and standard deviations for all sugars were reduced markedly. Removal of interfering amino acids in a beet juice from a sweet water tank caused increases in mean concentrations for myo-inositol (+4.2%) and particularly for glucose (+62.5%), and a decrease for fructose (−7.3%). ©     

Barley for Brewing: Characteristic Changes during Malting,Brewing and Applications of its By‐Products

ABSTRACT: Barley is the basic raw material for brewing. Its chemical composition, brewing, and technological indices are highly determinative for the beer quality and the economical efficiency of the brewing process. Barley is rich in protein, carbohydrates, dietary fibers, minerals, and vitamins. The presence of nonstarch polysaccharides as mixed linkage (1‐3),(1‐4)‐β‐d ‐glucans and arabinoxylans together with the enzymes are responsible for barley modification. Malting is a complex process that involves many enzymes; important ones are α‐amylase, β‐amylase, α‐glucosidase, and limit dextrinase. During the process of malting and brewing, the by‐products left after separation of the wort are rich in protein, fibers, arabinoxylans, and β‐glucan. This review summarizes and integrates barley grain with respect to nutritional, functional, and compositional changes that take place during malting and brewing. It also explores in‐depth the several by‐products obtained after brewing and their potential for various food applications. Barley brewing by‐products offer an opportunity for cereal‐based baked and extruded products with acceptable sensory and nutritional characteristics.     

Influence of sorghum grain type on wort physico‐chemical and sensory quality in a whole‐grain and commercial enzyme mashing process

To determine the most suitable types of sorghum for whole‐grain adjunct in lager beer brewing, 14 cultivars of five different types: white tan‐plant, white non‐tan‐plant, red non‐tannin, white tannin (type II) and red tannin (type III) were evaluated. The effects of grain type on wort physico‐chemical and sensory quality with raw grain and malt plus commercial enzyme mashing were assessed. Tannin content correlated significantly and negatively with wort extract and fermentable sugars (p < 0.001) and free amino nitrogen (FAN; p < 0.1). This is attributable to inactivation of the exogenous enzymes by the tannins during the mashing process. However, the type II tannin sorghums had wort quality attributes closer to the non‐tannin sorghum types, probably owing to their relatively low tannin content (≤1%). Malting gave a great improvement in wort extract, fermentable sugars and FAN, but substantially influenced wort sensory properties in terms of higher sourness, bitterness and astringency, as well as the expected more malty flavour. Worts from raw red non‐tannin sorghums were similar to those of white tan‐plant sorghums in both physico‐chemical and sensory quality. Thus, red non‐tannin sorghums, in view of their better agronomic quality, have considerable potential as a whole‐grain adjunct in lager beer brewing. Copyright © 2013 The Institute of Brewing & Distilling     

HORACE BROWN MEMORIAL LECTURE A CONSPECTUS OF BREWING PROGRESS

Horace Brown, who started as a brewer just over a hundred years ago, was an outstanding pioneer in the introduction of science to explain and guide brewing practice. His own and Pasteur's work saved brewing from repeated crises due to spoilage infections and so made it safe to brew thoughout the year. Attempts to control infection gave rise to Brown's great interest in the nitrogen compounds and led him to notable discoveries, apart from his outstanding work in many other fields. The writer followed with researches on the nitrogen compounds of barley, malt, wort and beer. These are summarized here and the potentialities for further developments today in the study of proteins are outlined. Against the background of the changing scene in brewing, a summary is given of the writer's further work on the agricultural aspects of barley growing, on barley germination and malting and on “sediment action” and yeast nutrition in fermentation. In addition a summary is given of his contributions in biological engineering, to continuous fermentation and to a scientifically-based conditioning process, using lupulin extracted from hops and incoporating a greatly accelerated haze-prevention method, which is economical. While drastically shortening the process, this and the other stages have been beneficial rather than otherwise to beer flavour.     

Infrared spectral analysis of sugar profiles of worts from varying grist to liquor ratios using infusion and ramping mash styles

Fermentability is an important trait for the brewing industry. Current industry methods lack the predictive capacity to accurately estimate how well a wort will ferment in the brewhouse. Wort from two mashing styles (high‐temperature infusion and low‐temperature ramping), and under varying grist to liquor (G:L) ratios, were produced and the differences in maltose, maltotriose and glucose were measured. The two mashing styles showed differences in original extract (Plato) values between the G:L ratios with a 1:2 G:L having the highest original extract. Maltose was the most abundant sugar in all sample types. All worts were scanned using Fourier transform infrared (FTIR) and the spectra also showed differences between the original extract and final extract with most of the changes around the spectral region associated with carbohydrates, a result of sugar utilization by the yeast. FTIR calibrations for extract and fermentable sugars all had r² values >0.98, with ratio of standard error of prediction to standard deviation >5. The results indicated changing fermentable sugar levels, thus making a prediction of fermentability possible. The FTIR also provided a rapid measure of changes in the fermentable sugar profile, which could assist maltsters and brewers in monitoring malt and beer quality. Copyright © 2016 The Institute of Brewing & Distilling     

Carbohydrate Make-up of Chick Pea,Cow Pea and Horse Gram

Extraction with 70% ethanol of chick pea, cow pea and horse gram yielded 7.1, 8.1 and 3.6%, respectively of free sugars, all showing the presence of galactose, glucose, sucrose, raffinose, stachyose and verbascose in varying proportions. Starch was isolated in 28 – 37% yields; whereas the unavailable carbohydrates were found to be 17.6, 14.5 and 24.2% respectively. All the fractions contained uronic acid, pentoses and hexoses in different proportions. No ethanol-soluble sugar or starch was detectable in the husk. The husk was rich in cellulose which still contained small amounts of pentose constituents, indicating probably its incomplete extraction or a strong macromolecular association.