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Beer Carbohydrates
Abstract
Cereals provide the carbohydrates for beer production. Barley that has been malted is the most usual cereal used. However, other cereals, including wheat, rice, maize, oats, sorghum and sugar syrups, may also be used. During malting all enzymes necessary for total degradation of starch are synthesized and/or activated, together with enzymes that contribute to the hydrolysis of β-glucans and in less extension arabinoxylans. Important transformations occur during mashing, namely, starch is converted into maltose and dextrins. Carbohydrates form 90% of the wort extract, 64-77% of which is usually fermentable by yeast to produce ethanol and carbon dioxide. Carbohydrate levels in beer range from 3 to 61 g/l. Specific data concerning the beer carbohydrate contents reported by different authors are presented. Different contents of total and fermentable sugars are reported according to beer type. Lagers are in general more fully fermented than ales. Total carbohydrate content of lager and ale beers range between 10-30 and 15-60 g/l, respectively. Lagers also contain less residual carbohydrates than ales, 1-7 g/l and 5-10 g/l, respectively. New brewing styles include fully attenuated low carbohydrate beers that contain less carbohydrate amounts (4-9 g/l) because dextrins have been more or less completely digested and fermented. In general, non-alcohol beers produced by short fermentation present higher level of fermentable sugars (about 55 g/l).
... As a result of the above-discussed constraints, the concentration of dextrins in the finished beer, which can be assumed practically unchanged from the respective concentration in the wort, usually falls between 10 and 50 g/L (Langstaff and Lewis, 1993), and, most often, between 10 and 40 g/L (Ferreira, 2009). ...
... Unfermentable sugars have been observed to constitute between 23% and 36% of all wort carbohydrates at mashing-out (Ferreira, 2009). In turn, dextrins constitute 75%-80% of unfermentable sugars in the wort (Bréfort et al., 1989), therefore, the ratio of dextrins to total carbohydrates can be expected in the range 17%-29%, with measured values averaging around 20% (Ferreira, 2009 ...
... Unfermentable sugars have been observed to constitute between 23% and 36% of all wort carbohydrates at mashing-out (Ferreira, 2009). In turn, dextrins constitute 75%-80% of unfermentable sugars in the wort (Bréfort et al., 1989), therefore, the ratio of dextrins to total carbohydrates can be expected in the range 17%-29%, with measured values averaging around 20% (Ferreira, 2009 ...
... It was hypothesized that total fermented sugars would be associated with the sweetness and coating sensations, however, the present results did not show this relationship. Since the TS analysis quantifies only small sugar units, instrumental analysis of carbohydrates, like dextrins, pentosans and β-glucan could potentially be a better prediction for the coating mouthfeel (Ferreira, 2009;Langenaeken et al., 2020). Therefore, small sugar molecules cannot contribute to the sweetness and coating sensation, while the investigation of larger sugar-based molecules, like carbohydrates, could be dominant for the prediction of those sensations. ...
... According to our results, dextrin concentration increases with the content of the dark malts used. Dextrins do not undergo ethanol Molecules 2020, 25, 3882 8 of 18 fermentation using the classic strains of Saccharomyces cerevisiae brewer's yeast, therefore their amount in the wort is similar to that in the beer [38]. ...
The aim of this study was to assess the possibility of shaping properties of beers at the stage of brewing wort production with the use of various types of special malts (chocolate pale, chocolate dark, wheat chocolate, brown barley) and roasted barley grains. The carbohydrate profile, polyphenols content, antioxidant capacity, 5-hydroxymethylfurfural content, and the browning index level were analyzed. Statistical analysis showed significant differences in the values of the examined features between the samples. The sugars whose content was most affected by the addition of special malts were maltose and dextrins. The polyphenol content in worts with 10% of additive was 176.02–397.03 mg GAE/L, ferric reducing antioxidant power (FRAP) 1.32–2.07 mmol TE/L, and capacity to reduction radical generated from 2,2′-Azino-bis(3-ethylbenzothiazoline-6-sulfonic acid) diammonium salt (ABTS•+) 1.46–2.70 mmol TE/L. Wort with 40% dark malt showed the highest content of polyphenolic compounds and antioxidant activity (FRAP and ABTS•+). The HMF content and the browning index value were higher for wort with the addition of darker-colored malts (EBC) and increased with increasing dark malt dose.
... The depolymerization processes are classified into cytolysis (degradation of cell wall polysaccharides), proteolysis (degradation of proteins into amino acids and peptides), and amylolysis (degradation of starch into fermentable carbohydrates) [13]. Dextrins are derived from the partial hydrolysis of starch (α-1-4-and α-1-6-linked d-glucose monomers) and vary in their molar mass [3,22]. Hemicelluloses are cell wall polysaccharides derived from the barley cell wall during cytolytic degradation that consist of 80-90% β-glucans (β-1-3-and β-1-4-linked glucose monomers) and 10-12% pentosans [23,24]. ...
The sensory attribute palate fullness of cereal-based beverages was shown to be affected by polymeric compounds and their macromolecular profile. During malting, the enzymatic degradation of polymers is technologically controlled by the malting parameters, namely the degree of steeping, germination time, and germination temperature. The macromolecular profile of a fermented cereal-based beverage consists of non-fermentable substance classes. Therefore, the macromolecular composition of a final beverage is originally dominated by the raw material, if conventional production methods are used. We investigated the influence of different cytolytic and proteolytic malt modifications on the macromolecular profile of lactic acid-fermented cereal-based beverages (a strain was selected that did not produce exopolysaccharides) and their resultant effect on the sensory perception of the attributes of palate fullness and mouthfeel. Asymmetrical-flow field-flow fractionation coupled with multi-angle light-scattering detection and refractive index detection is an analytical tool for macromolecular characterization to indicate differences in the macromolecular profile, molar mass, and molar mass distribution. The beverages produced using different modified malts demonstrated a considerable variation in their final composition, particularly in the composition of their macromolecular compounds. A higher level of malt modification led to a decrease in the high-molar-mass fraction and a consequent shift toward fractions with a lower molar mass. Malts produced from barley with increased crude protein contents resulted in a greater range within the macromolecular profile. The variation of germination time significantly influenced the number average molar mass, the total refractive index detection (dRI) peak area, and the high-molar-mass fraction, which contained cell wall polysaccharides (60–1200 kDa). The perception of the intensity of palate fullness was significantly correlated with specific macromolecular fractions, which were influenced by the malting parameter degree of steeping and the resultant modification. The perception of the mouthfeel descriptor watery varied significantly for different crude protein contents. Our results are beneficial for a targeted design of beverage composition based on the macromolecular profile by an improved selection of raw materials and malting technology.
... Of interest, but perhaps it should be thought as a concern, is the lack of correlation in the total amount of starch and the two key malt specifications, namely the hot water extract (sweet wort) and fermentability, both measured in laboratoryscale tests. A number of publications have demonstrated positive correlations between fermentable sugars (maltose and maltotriose) and fermentability (Evans et al., 2005;Koljonen et al., 1995;Ferreira, 2009;De Rouck et al., 2013). Furthermore, the inclusion of the individual malt enzymes mentioned above and other malt parameters have been used in simple regression models to predict fermentability. ...
Fermented beverages have been consumed by humans for thousands of years. As humans started to farm rather than hunt, and using grasses that were growing locally, such as the wild species of modern barley (Hordeum vulgare) and the Hordeum spontanium species, they also inadvertently developed a very basic fermentation process. Over millennia, as humans cultivated grains other than barley, usually because barley was not suitable to that environment, nonbarley beerlike beverages were also developed. The main use of the grains is for the starch to be reduced to its basic core unit, glucose, which is easily fermented. This chapter will focus on barley and other cereals used in brewing and also consider other fermented and or distilled products such as hiposho (a small amount of malt) in Japan and baijiu in China, which uses barley and other cereal grains, primarily to use the starch for fermentation.
... Beers are complex mixtures, including saccharides such as glucose, maltose and maltotriose. 38 The DOSY spectrum (Fig. 4a) showed a range of diffusion coefficients, but due to the large number of different components and the limited resolution, little detailed insight can be gained. The anomeric doublet at 5.23 ppm was selected for further analysis with a REST 2 experiment (Fig. 4b). ...
A new family of NMR experiments for mixture analysis (Relaxation-Encoded Selective TOCSY, REST) allows the extraction of component spectra from mixtures. It uses isotropic mixing to label whole spin systems with the relaxation times (e.g. T1, T2) of individual spins.
Article available here:
http://dx.doi.org/10.1039/C7CC03150E
... The analysis includes samples of the years 2011-2014, including sample variation from different sites. b Average determination by HPLC analyses of 18 lager beers reported in the literature (Ferreira, 2009). pH of the historic beer samples, the formation of glucosides with low molecular weight alcohols may result from enzymatic processes involving a-glucosidase instead. ...
In brewing, barley (Hordeum vulgare L.) malt is increasingly being replaced by other cereals. This stems from the desire to add new characteristics to beer and/or to improve the brewing process or cost of production. This research aimed to analyse the effect of different percentage shares (0, 10, 50 and 100%) of oat (Avena sativa L.) malt in the recipe on the course of top-fermented beer production. The analysis conducted did not show any negative effect of the application of 10% share of oat malt in the recipe on the brewing process and the quality of the final product, as compared to the no-oat-malt recipe. On the other hand, in the case of higher oat malt content, prolongation of lautering time (up to ca. 120 min), lower quantity of wort (up to ca. 30%), its extract content (up to ca. 35%), and thus alcohol concentration, as well as intensified colour of beer were observed. In oat and barley beers, the content of D-chiro-inositol was below the detection threshold, while small amounts of myo-inositol were determined in the samples. Furthermore, the application of oat malt affected the ionic content of the wort and did not affect the level of phenolic compounds.
Functional beers are increasing in popularity amid the craft beer movement and rising trends in health and wellness. Within this category, probiotic and prebiotic beers are a novelty and, due to their health benefits, could make significant contributions within the brewing industry. Studies exploring the use of different types of probiotics (Lactobacillus spp., Saccharomyces cerevisiae var. boulardii, and Bacillus spp.) to brew beers have recently emerged. In contrast, prebiotic beers remain relatively unexplored, which is unfortunate as there is great potential in enriching beers with the candidate prebiotics, arabinoxylan-oligosaccharides, and β-glucans, via in situ production. Nevertheless, there are difficulties in developing probiotic and prebiotic beers, and very often, modifications to existing brewing practices need to be made. Furthermore, despite potential therapeutic benefits compared to regular beers, health-promoting messages must abide by local legislations in order to safeguard consumer health against the deleterious effects of excessive alcohol consumption.
Controlled hydrodynamic cavitation techniques and methods are finally achieving industrial uptake, even as single-unit operation systems, with beer manufacturing as a distinct success story. Although they are relatively simple in concept and practical implementation, and generally lead to remarkable benefits, a certain resistance on the industry side, along with still insufficient fundamental and experimental research, is slowing their spread, particularly in the food sector. This chapter offers an up-to-date review of the state of the art, as related to fundamentals, trends, and future directions, in the applications of hydrodynamic cavitation to beer brewing and the processing of juices and other plant-based beverages.
Lactobacillus (L.) brevis represents a versatile, ubiquitistic species of lactic acid bacteria, occurring in various foods, as well as plants and intestinal tracts. The ability to deal with considerably differing environmental conditions in the respective ecological niches implies a genomic adaptation to the particular requirements to use it as a habitat beyond a transient state. Given the isolation source, 24 L. brevis genomes were analyzed via comparative genomics to get a broad view of the genomic complexity and ecological versatility of this species. This analysis showed L. brevis being a genetically diverse species possessing a remarkably large pan genome. As anticipated, it proved difficult to draw a correlation between chromosomal settings and isolation source. However, on plasmidome level, brewery- and insect-derived strains grouped into distinct clusters, referable to a noteworthy gene sharing between both groups. The brewery-specific plasmidome is characterized by several genes, which support a life in the harsh environment beer, but 40% of the brewery plasmidome were found in insect-derived strains as well. This suggests a close interaction between these habitats. Further analysis revealed the presence of a truncated horC cluster version in brewery- and insect-associated strains. This disproves horC, the major contributor to survival in beer, as brewery isolate specific. We conclude that L. brevis does not perform rigorous chromosomal changes to live in different habitats. Rather it appears that the species retains a certain genetic diversity in the plasmidome and meets the requirements of a particular ecological niche with the acquisition of appropriate plasmids.
We wanted to identify key factors influencing the extent of β-glucan production by Lactobacillus brevis TMW 1.2112, which has been isolated from viscous, spoiled beer and which could contribute to viscosity increases of spoiled beverages via exopolysaccharide (EPS) production. In this way, we analyzed the influence of different initial pH values and carbohydrate sources on growth of and slime/β-glucan formation by this strain. In a screening of 48 carbohydrates, 14 fermentable sugars which enabled growth were identified. These sugars were further investigated regarding their EPS formation-promoting properties. The hexose-based mono- and di-saccharides enabled slime formation, while all pentoses failed to cause any thickening effect. The strongest slime formation was observed upon growth on d-maltose, the weakest on d-fructose. A lower initial pH (4.3) caused significant higher viscosities than an initially higher one (pH 6.2). This effect was independent from the carbohydrate supplied. Although the thickening of nutrient media by L. brevis TMW 1.2112 strongly depended on the initial pH and the available carbon source, all isolated polysaccharides were exclusively composed of glucose moieties and exhibited highly similar elution profiles after separation via asymmetric flow field-flow fractionation independently of the provided carbon source. Our results suggest that the extent of β-glucan/slime formation by special L. brevis strains isolated from the brewery environment is strongly influenced by the initial pH and the availability of certain EPS formation-promoting sugars with maltose being the most favored carbohydrate for the regulated and directive biosynthesis of capsular β-glucan.
Cereal-based beverages contain a complex mixture of various polymeric macromolecules including polysaccharides, peptides, and polyphenols. The molar mass of polymers and their degradation products affect different technological and especially sensory parameters of beverages. Asymmetrical flow field-flow fractionation (AF4) coupled with multi-angle light scattering (MALS) and refractive index detection (dRI) or UV detection (UV) is a technique for structure and molar mass distribution analysis of macromolecules commonly used for pure compound solutions. The objective of this study was to develop a systematic approach for identifying the polymer classes in an AF4//MALS/dRI/UV fractogram of the complex matrix in beer, a yeast-fermented cereal-based beverage. Assignment of fractogram fractions to polymer substance classes was achieved by targeted precipitations, enzymatic hydrolysis, and alignments with purified polymer standards. Corresponding effects on dRI and UV signals were evaluated according to the detector’s sensitivities. Using these techniques, the AF4 fractogram of beer was classified into different fractions: (1) the low molar mass fraction was assigned to proteinaceous molecules with different degrees of glycosylation, (2) the middle molar mass fraction was attributed to protein–polyphenol complexes with a coelution of non-starch polysaccharides, and (3) the high molar mass fraction was identified as a mixture of the cell wall polysaccharides (i.e., β-glucan and arabinoxylan) with a low content of polysaccharide–protein association. In addition, dextrins derived from incomplete starch hydrolysis were identified in all fractions and over the complete molar mass range. The ability to assess the components of an AF4 fractogram is beneficial for the targeted design and evaluation of polymers in fermented cereal-based beverages and for controlling and monitoring quality parameters.
To produce experimental beers, different mash mixtures (barley malt, barley malt + 30% pre‐cooked maize, barley malt + 30% nonmalted spelt) and distinct mashing procedures (infusion and decoction) with variations of the rest time and initial temperatures were evaluated. The range of molecular weight distribution (MWD) of the resulting beers was determined using asymmetrical flow field flow fractionation coupled to multiangle laser light scattering and refractive index. There were no differences on the range of MWD among the beers, according to infusion or decoction, using similar raw materials and initial temperatures (45 and 55°C). However the range of MWD was higher (p p p Document Type: Research Article DOI: http://dx.doi.org/10.1002/jib.69 Publication date: September 1, 2013 $(document).ready(function() { var shortdescription = $(".originaldescription").text().replace(/\\&/g, '&').replace(/\\, '<').replace(/\\>/g, '>').replace(/\\t/g, ' ').replace(/\\n/g, ''); if (shortdescription.length > 350){ shortdescription = "" + shortdescription.substring(0,250) + "... more"; } $(".descriptionitem").prepend(shortdescription); $(".shortdescription a").click(function() { $(".shortdescription").hide(); $(".originaldescription").slideDown(); return false; }); }); Related content In this: publication By this: publisher By this author: Rübsam, Heinrich ; Gastl, Martina ; Becker, Thomas GA_googleFillSlot("Horizontal_banner_bottom");
Saccharomyces yeast biomass is the second major by-product from brewing industry. It can be of value as a raw material with different uses, however, it is still underutilized, mostly, for swine and ruminant feed. This review aims to give a brief overview on applications for this agro-industrial by-product as a source of nutrients for human and fish nutrition, microbial growth, production and industrial use of brewer's yeast components and highlight the needs for further investigations and research, especially in the areas of production of ingredients for functional foods and the use of brewer's yeast as agents of detoxifying effluents containing heavy metals.
The effect of beer or red wine marinades on the reduction of heterocyclic aromatic amines (HAs) formation in pan-fried beef was compared. The cooking experiments were performed under well-controlled temperature and time conditions. The samples were analyzed for HAs contents using solid-phase extraction and high-performance liquid chromatography-diode array detection/fluorescence detection. Unmarinated samples cooked in similar conditions provided reference HAs levels. Marinating with beer or with red wine resulted in decreased levels of HAs. The amount of 2-amino-1-methyl-6-phenylimidazo[4,5-b]pyridine and 2-amino-3,8-dimethylimidazo[4,5-f]quinoxaline reduced significantly, respectively, around 88 and 40% after 6 h of marinating with beer or with wine. High variations were observed for reductions of AalphaC, ranging between 7 and 77%. Only beer marinade significantly reduced the levels of 4,8-DiMeIQx at 1, 2, and 4 h of marinating. Multivariate statistical treatment of results indicated that beer can be more efficient on the reduction of some HAs formation. In addition, results from descriptive sensory analysis of unmarinated and 2 h marinated beef samples, tested for by two trained sensory panels, pointed to beer marinade as the most adequate for maintaining the usual overall appearance and quality of the pan-fried steaks.
Complete separation of fermentable and non fermetabile carbohydrates of up to 15 glucose units in wort, mashed malt and beer was obtained in 40 minutes by direct injection on a NH2 column and an HPLC-ELSD apparatus. The results were comparabile with those found with the official HPLC-RI procedure and with chemical determination with Feheling's reagent. In Italian wort and mashed malt, about 88% of the total carbohydrates are fermentable, while in beer only 29% are fermentable.
Beer brewing is an intricate process encompassing mixing and further elaboration of four essential raw materials, including barley malt, brewing water, hops and yeast. Particularly hops determine to a great extent typical beer qualities such as bitter taste, hoppy flavour, and foam stability. Conversely, hop-derived bitter acids account for an offending lightstruck flavour, which is formed on exposure of beer to light. These various processes are presented in detail, while due emphasis is placed on state-of-the-art hop technology, which provides brewers with efficient means to control bitterness, foam, and light-stability thereby allowing for the production of beers with consistent quality.
A high-performance liquid chromatographic method is proposed for the simultaneous separation of main carboxylic acids, carbohydrates,
ethanol, glycerol, and 5-HMF in beer by direct injection. A column packed with a sulfonated divinyl benzene-styrene copolymer
and an isocratic elution with 0.0045N sulfuric acid and acetonitrile (6%, v/v) are employed. UV and refractive index detectors
connected in series are also used to reduce the matrix interference of phenolic compounds. In conditions described, nine compounds
are quantitated in a single chromatographic run without any pretreatment except for sample dilution and filtration before
injection. Precision, accuracy, linearity of response, limit of detection, and limit of quantitation are also evaluated for
each compound. Satisfactory results are obtained to justify the application of this method to all phases of beer production
for process and quality control.
A trifactorial experiment with a level of confidence of P < 0.05 was performed to study worts and lagers produced with barley or sorghum malts, refined maize (MZ), or waxy sorghum (WXSOR) grits treated during mashing with or without amyloglucosidase (AMG). Worts were produced from the different malts, type of adjunct, and enzyme treatment combinations following a double-mashing procedure. The diastatic activity levels of the barley and sorghum malts were 119 and 20°Lintner, respectively. The barley malt produced 35% more 12°Plato (°P) wort with higher amounts of free amino nitrogen and total fermentable carbohydrates compared with counterparts produced from sorghum malt. The barley malt wort contained higher amounts of maltose but lower amounts of glucose compared with the sorghum malt wort. The WXSOR grits produced worts with similar yield and properties as did the worts produced from MZ grits. AMG addition led to a 3% increment on wort yield and increased glucose from 9.3 to 21.5 g/L of wort and total fermentable sugar equivalents from 59.2 to 72.6 g/L of wort. After 144 hr of fermentation, lagers from barley malt and treated with AMG contained 1.0 and 0.25% units higher ethanol than did the counterparts produced from sorghum malt and without AMG. For AMG treated beers, nonsignificant differences in ethanol content were observed between samples mashed with barley malt and beers produced from sorghum malt and MZ grits. Results demonstrated that AMG could be used to increase the initial amount of fermentable sugars especially in sorghum mashes.
Saccharides labeled with the dye 8-amino-1,3,6-naphthalene trisulfonic acid can be separated by electrophoresis and detected with fluorescence-assisted carbohydrate electrophoresis (FACE). Optimization of labeling time at 65°C enables same-day analysis of assay results. Oligosaccharides in beer can be identified in FACE assays based on comigration with standards (e.g., oligosaccharides derived from purified starch, β-glucan, and pentosan). A variety of beers, including lager, light, ale, porter, and stout, demonstrated distinct saccharide patterns in FACE analysis.
No standardized method exists for the determination of total or individual carbohydrates in beer and this could cause difficulties in view of regulatory requirements for labelling. A comparative study of known methods likely to be most suitable for the measurement of total carbohydrate in beer was therefore undertaken. Methods were also examined for estimating other important residual carbohydrates in beer, such as residual fermentable carbohydrates, β-glucan, total fructose and fructosans, and total pentose and pentosans. The beers analysed covered a wide range of carbohydrate levels and, as expected, the different methods gave different values for the carbohydrate content of the same beer. We consider that the colorimetric anthrone-sulphuric acid procedure (Yadav's version) is to be preferred for estimating the total residual carbohydrate content of beer. It is less prone to interference, relatively simple, rapid and gives more accurate results than acid or enzymic hydrolysis in combination with reductometric procedures. The within-laboratory coefficient of variation is 1.68%.
The influence of hydrophobic polypeptides concentrated in beer foam, together with the composition of iso-alpha acids and the content of malto-oligosaccharides in beer on foam stability, has been investigated. The objective was to find out whether a shortage of one of these positive contributors to foam stability could be compensated for by an increased presence of another or whether optimum levels of each contributor is necessary. For that purpose, an image analysis method to evaluate beer foam quality was developed. The foam collapse time was the parameter chosen to group beers according to their foam stability. Profiles of hydrophobic polypeptides that concentrate in beer foam, iso-alpha acids, and malto-oligosaccharides of 14 beer brands were acquired by high-performance liquid chromatography. Principal component analysis (PCA) was performed to show the relationship between beer brands and its composition. Beers that contained propylene glycol alginate as a foam enhancer showed high foam stability except for one beer, which had a low content of hydrophobic polypeptides, thereby highlighting the requirement of threshold levels of hydrophobic polypeptides to obtain stable foam. The data of samples that were devoid of a foam additive were subjected to a discriminant statistical analysis. Foam stability declined in proportion to decreases in hydrophobic polypeptides and to a lesser extent to decreases in iso-alpha-acid contents. Apparently, the content of malto-oligosaccharides were found to have no major influence on foam stability. The model of discriminate analysis was found to explain 100% of the variance in data with 85.2% success in classifying all samples according to the model, suggesting that foam stability is mainly governed by the beer constituents evaluated in this study.
Determination of malto-oligosaccharides and monosaccharides is important for controlling brewing processes and for characterization of final product taste by making a correlation between sensory impressions and quantitative measurement of the components. Amino-layer HPTLC (high-performance thin-layer chromatography) associated with AMD (automated multiple development ) has been evaluated for use in monitoring of maltotetraose, maltotriose, glucose, and fructose in different beers. The AMD-HPTLC system allows one to operate under gradient conditions and to separate complex mixtures of components within large intervals of polarity. In this case the gradient was based on acetonitrile-acetone-water. The results obtained show that the low detection limit, the absence of clean-up procedures, and the high sample throughout make this method suitable even for use on a large scale, thus making it possible to control the main fermentation components in commercial beers.
A series of singly branched α-dextrins with dp ≥ 5 was prepared by treating amylopectin with an α-amylase (Termamyl) and then with β-amylase. The dextrins were separated by gel filtration chromatography and the composition of the fractions was checked by HPAEC. Each fraction gave essentially a single peak by HPAEC but NMR spectroscopy indicated that only the fraction corresponding to dp5 consisted of one compound. The fractions corresponding to dp6, 7 and 8 were found to be mixtures of isomers. Three isomers of dp6 were separated by reversed phase HPLC and were characterised by NMR spectroscopy. The isomers were identified as 62-α-maltotriosyl-maltotriose, 63-α-maltosyl-maltotetraose and 62-α-maltosyl-maltotetraose. 1H and 13C NMR parameters of these compounds and of dp5, 62-α-maltosyl-maltotriose, are discussed in relation to the linkage pattern of the different glucose units and compared with similar parameters in the linear maltodextrins.
Two detection systems for sugar HPLC identification, were compared, namely IR and ELSD. Peak separation was carried out on an adapted BECKMAN HPLC chromatographic line with the two detectors in series. This assembly line allowed the superimposition of two detection features on an single chromatogram. The same sugar mixture injection should be identified with both systems in the same conditions. Three separation devices were used.It was demonstrated that the ELSD technique was well adapted for sugar determination. Compared with the RI detection, ESD showed a better sensitivity, more stability of the chromatographic base line and no incidence of the temperature.However, the main advantage of the ESLD system was the assessment of the gradient elution use, since this is excluded in RI detection.
In brewing science, "mashing" involves steeping malted barley in hot water. This activates the enzymes to breakdown the starch into simple sugars. The spent grains are then separated from the sweet wort. This experiment is an investigation of the chemistry and processes involved in mashing. Crushed malted barley is mixed with hot water and the progress of the reaction is monitored by using a simple iodine test for starch. This offers a very interesting way to study the enzymatic hydrolysis of starch. Keywords (Audience): First-Year Undergraduate / General
J. Inst. Brew. 111(3), 259–264, 2005 The enormous incidence of excess body weight in the popu-lation of the United States and the attendant risks that obesity brings has stimulated unprecedented interest in diets, especially those that do not leave an individual feeling hungry. In particular this has led to so-called 'low carb' diets. Beer has suffered un-fairly through erroneous claims made in connection with at least one of these diets and has been unfairly categorised as being "high carb". In the face of this – and despite the fact that the vast majority of beers contain low levels of so-called "carbs" – there have been certain brands specifically branded as low carb prod-ucts. Brewers intent on marketing products that may genuinely be considered to be part of a "calorie counting" diet should fo-cus on developing products of excellence that contain low levels of alcohol, the latter molecule being the major source of calories in most beers. They may also do more to press the claim of beer as being a source of "good carbs", for the soluble fibre and pre-biotic molecules that it contains and which are derived from the -linked glucans and arabinoxylans that derive from the cereal cell walls.
The first total separation by electrophoresis of five carbohydrates, sucrose, maltotriose, maltose, glucose and fructose, is described. The basic technique requires 1-naphthylacetic acid as background electrolyte at pH 12.5, indirect UV detection at 222 nm, with a capillary of 75 µm × 120 cm and a voltage of 25 kV. Linear calibration curves from 50 to 400 mg l−1 with a good correlation coefficient were obtained. The method has been used to determine carbohydrates during the brewing process of a non-alcoholic beer and also to analyse the carbohydrate content of dietetic fruit juices and chocolate. Copyright © 2004 Society of Chemical Industry
Six endoglucanases (Endo I, II, III, IV, V, and VI), three exoglucanases (Exo I, II, and III), and a beta -glucosidase ( beta -gluc I) isolated from a commercial cellulase preparation of Trichoderma viride origin were examined as to their activities on xylan ex oat spelts. Endo I, II, and III as well as Exo II and III showed no activity toward xylan and were classified as specific glucanases. Less specificity was found for the endoglucanases Endo IV, V, and VI, Exo I, and beta -gluc I, whose enzymes were able to hydrolyze xylan. With respect to product formation these xylanolytic cellulases fit the classification of xylanases generally accepted in the literature. Kinetic experiment with xylan, CM-cellulose, and p-nitrophenyl- beta -D-glucoside revealed that Endo IV, V, and VI and Exo I prefer to hydrolyze beta -1,4-D-glucosidic linkages. beta -Gluc I showed no clear substrate preference.
Separation of the low molecular weight fraction of oligosaccharides from beer and subsequent NMR analysis led to the identification of several new derivatives of trehalose, sucrose, maltooligosaccharides glucosylated at O-2 of reducing end Glc, and linear Glc oligomers with alpha-(1-->3) and alpha-(1-->4)-linkages. Reducing oligosaccharides were labeled with 7-amino-4-methylcoumarin by reductive amination, separated according to their molecular weight and the branching pattern was studied using enzymatic (pullulanase) degradation in combination with MALDI-TOF mass spectrometry and HPLC analysis. It was found that up to DP 10 isomaltooligosaccharides mostly consisted of a linear reducing alpha-(1-->4)-linked Glc chain substituted by single maltose or maltotriose residue at O-6 of any residue except the reducing one.
The application of LC-NMR/MS for the direct identification of carbohydrates in beer has been studied. Carbohydrates are major beer components, and their structural characterization by NMR alone is seriously hindered by strong spectroscopic overlap. Direct analysis of beer by LC-NMR/MS enables the rapid (1-2 h) identification of dextrins with degree of polymerization (DP) of up to nine monomers, with degassing being the only sample treatment required. Although the presence of alpha(1-->6) branching points is easily indicated by NMR for each subfraction separated by LC, difficulties arise for the unambiguous assignment of linear or branched forms of high DP dextrins. The two beer samples investigated in this work were found to have significantly different oligosaccharide compositions, reflecting the different production conditions employed. The use of hyphenated NMR for the rapid characterization of the carbohydrate composition of beers may be the basis of a useful tool for the quality control of beer.
Carbohydrates have been separated on POLYSPHER(R)CH OH columns using pulsed amperometric detection (PAD) and UV detection (lambda =196 nm) in series and pure water as mobile phase. Nearly baseline separations have been obtained for the glycoprotein carbohydrates of sialic acid ( N-acetylneuraminic acid, NANA), N-acetylglucosamine (GlcNAc) and N-acetylgalactosamine (GalNAc). As carbohydrates dissolved and eluted with pure water are present in the neutral form they are not detectable with PAD in contrast to carbohydrate anions formed at high pH values. Therefore an additional NaOH post column reagent has been continuously pumped through a mixing chamber into the mobile phase to form carbohydrate anions resulting in improved detection limits. Monosaccharides as well as glycoprotein carbohydrates could be detected in the microg/ml-range. This method has been applied successfully to the analysis of sugars in fruit juice. With only 2 microl of juice per 50 ml water, the determination of the main constituents, sucrose, glucose and fructose, was possible in a few minutes without sample preparation.
An HPLC method with an evaporative light scattering detector was optimized and validated for quantification of carbohydrates in beer. The chromatographic separation was achieved using a Spherisorb NH2, 5 microm chromatographic column and gradient elution with acetonitrile/water. The determinations were performed in the linear range of 0.05-5.0 g/L for fructose, 0.05-5.0 g/L for glucose, 0.05-15.0 g/L for maltose, 0.05-10.0 g/L for maltotriose, and 0.05-5.0 g/L for maltotetraose. The detection limits were 0.005 g/L for fructose, 0.008 g/L for glucose, and 0.01 g/L for maltose, maltotriose, and maltotetraose. The reliability of the method in terms of precision and accuracy was evaluated in three beer matrices, low alcohol beer, 6% alcohol beer, and beer made with part of adjuncts (4.5% alcohol). Relative standard deviations (RSDs) ranged between 1.59 and 5.95% (n = 10), and recoveries ranged between 94 and 98.4%.
A versatile liquid chromatographic platform has been developed for analysing underivatized carbohydrates using high performance anion exchange chromatography (HPAEC) followed by an inert PEEK splitter that splits the effluent to the integrated pulsed amperometric detector (IPAD) and to an on-line single quadrupole mass spectrometer (MS). Common eluents for HPAEC such as sodium hydroxide and sodium acetate are beneficial for the amperometric detection but not compatible with electrospray ionisation (ESI). Therefore a membrane-desalting device was installed after the splitter and prior to the ESI interface converting sodium hydroxide into water and sodium acetate into acetic acid. To enhance the sensitivity for the MS detection, 0.5 mmol/l lithium chloride was added after the membrane desalter to form lithium adducts of the carbohydrates. To compare sensitivity of IPAD and MS detection glucose, fructose, and sucrose were used as analytes. A calibration with external standards from 2.5 to 1000 pmole was performed showing a linear range over three orders of magnitude. Minimum detection limits (MDL) with IPAD were determined at 5 pmole levels for glucose to be 0.12 pmole, fructose 0.22 pmole and sucrose 0.11 pmole. With MS detection in the selected ion mode (SIM) the lithium adducts of the carbohydrates were detected obtaining MDL's for glucose of 1.49 pmole, fructose 1.19 pmole, and sucrose 0.36 pmole showing that under these conditions IPAD is 3-10 times more sensitive for those carbohydrates. The applicability of the method was demonstrated analysing carbohydrates in real world samples such as chicory inulin where polyfructans up to a molecular mass of 7000 g/mol were detected as quadrupoly charged lithium adducts. Furthermore mono-, di-, tri-, and oligosaccharides were detected in chicory coffee, honey and beer samples.
Six endoglucanases (Endo I, II, III, IV, V, and VI), three exoglucanases (Exo I, II, and III), and a beta-glucosidase (beta-gluc I) isolated from a commercial cellulase preparation of Trichoderma viride origin were examined as to their activities on xylan ex oat spelts. Endo I, II, and III as well as Exo II and III showed no activity toward xylan and were classified as specific glucanases. Less specificity was found for the endoglucanases Endo IV, V, and VI, Exo I, and beta-gluc I, whose enzymes were able to hydrolyze xylan. With respect to product formation these xylanolytic cellulases fit the classification of xylanases generally accepted in the literature. Kinetic experiment with xylan, CM-cellulose, and p-nitrophenyl-beta-D-glucoside revealed that Endo IV, V, an VI and Exo I prefer to hydrolyze beta-1, 4-D-glucosidic linkages. beta-Gluc I showed no clear substrate preference.