AMYLASE ACTIVITY AND ENDOSPERM HARDNESS OF HIGH LYSINE BARLEYS

Several of the high lysine barleys selected by the Udy dye binding method have altered proportions of the main protein fractions. These varieties also vary considerably in endosperm hardness measured as the amount of electrical energy required for milling. A few have endosperms requiring a higher milling energy than that of the parental variety, but five high lysine varieties have soft endosperms typical of barleys that malt readily. In addition the high lysine selections differ markedly in β-amylase and diastatic activity. Mutant R 1508 with the highest grain lysine has very low diastatic activity, whereas R 56 and Hiproly have diastatic activities equivalent to that of a known high diastase barley. α-Amylase activity of high lysine barleys also ranges widely and tends to be inversely related to diastatic activity.     

ENZYME DEVELOPMENT IN THE ALEURONE AND EMBRYOS OF GALANT AND TRIUMPH BARLEYS

The aleurone layer of the pro-anthocyanidin free barley, galant, produced less endo-beta-(1–3, 1–4) glucanase and alpha-amylase than the aleurone of triumph. The slower rate of endosperm breakdown (modification) of galant is associated with its reduced potential to produce the cell-wall-degrading enzyme, endo-beta-(1–3, 1–4) glucanase.     

CLASSIFICATION OF BARLEYS BASED ON MALTING QUALITY BY IMAGE ANALYSIS

Computerised image analysis was investigated as an automated quality control technique for rapid and precise classification of barleys according to their malting qualities. The nineteen samples used in this study were two-rowed winter type barleys. Six of these were assigned to Group 1 and the rest was included Into Group 2 according to their performance in a micro-malting system. Two sets of kernels from each barley sample were recorded, one for training and the other for testing purpose. To be able to have functions yielding the best discrimination scores in the training set, classification analysis was initially performed by the selection of each feature alone as an independent variable. Correct overall classification scores ranged between 52.9% and 78.1% when individual features were used in discriminant analyses. In the second step, the combination of features which yielded the best classification score was determined by stepwise discriminant analysis. Overall success in various combinations was more than 83%. To test the unknown barley samples, the discriminant function produced by the combination of compactness and equivalent diameter features was selected. Correct classification scores of this combination ranged between 60.0% and 94.7%. The result shows that the discrimination of the unknowns is very close to that achieved in the training set .     

EFFECTS OF CULTIVAR AND ENVIRONMENT ON β-GLUCAN CONTENT AND MALTING QUALITY OF TURKISH BARLEYS

Eight barley cultivars grown under the same agronomic conditions and samples of Tokak cultivar grown at six different sites of Turkey were used in this study. There were significant differences among the barley cultivars and growing locations in terms of β-glucan content (p<0.05). Among malt quality criteria tested for the 8 barley cultivars; friability, viscosity, Kolbach index and extract difference showed significant correlations (p<0.05) with the total β-glucan content. Similar correlations were also observed between the malt quality criteria (Kolbach index and extract difference) and β-glucan contents for the Tokak samples grown at different sites.     

RECOGNITION OF TWO LIPASES FROM BARLEY AND GREEN MALT

Lipase was extracted from ground samples of germinating and ungerminated barley, using the detergent Triton X-100. Enzyme activity, measured by the release of oleic acid from radioactively labelled triolein, was approximately half that in suspensions of barley flour. Two distinct lipases, both active at neutral pHs, and having similar molecular weights (around 400,000) but differing in their ionic properties, were isolated from barley. The more abundant lipase was found mainly in the embryo, while the other was located in the endosperm. Both total and extractable lipase activity increased during germination.     

THE MYCOFLORA OF BARLEYS ACCEPTED AND REJECTED FOR MALTING

Barleys were examined by direct and dilution plating before purchase for drying and subsequent malting. The mould flora of barleys rejected because of heating was characterised by lower proportions of field fungi, particularly Cladosporium spp, and higher proportions of storage fungi, particularly Aspergillus glaucus (group), than in undried barleys which had not heated. Results indicated that microbiological analysis could be used to resolve whether self-heating of undried barley has occurred on the farm before the barley has been delivered free of heat to meet a purchaser's specification.     

MALTING AND BREWING WITH BARLEYS HAVING BLUE ALEURONES

Blue aleurones in barley are associated with elevated levels of polyphenolic materials such as anthocyanins and anthocyanidins. A rapid method has been developed for assessing the anthocyanin content of barleys, malts and worts. Malts were prepared from a range of barleys, some of which had intensely blue aleurones, while others were only slightly blue or showed no visible pigmentation. The malting quality of barley was not affected by aleurone colour and ales and lagers of sound flavour as well as acceptable analytical parameters were brewed from malts having pronounced blue aleurones. In some cases sweet worts prepared from blue aleurone malts had a slight pinkish tinge, but this disappeared during wort boiling, and beer colours were normal. Levels of anthocyanins in barley correlated with those in malt and in wort. However, the concentration of anthocyanins was unrelated to the amount of anthocyanogens or total polyphenols. High anthocyanin levels in either barley or beer had no deleterious effects on beer flavour or the rate of haze development.     

LIPOXIDASES IN MALTING AND MASHING

Raw barley contains two lipoxidases and during malting the activity of both enzymes increases, although to differing extents. The amount of activity which develops depends upon the barley variety. Synthesis of lipoxidase during the initial stages of germination requires oxygen, and is lowered by treatments which reduce the availability of oxygen or which restrict embryo growth. Most of the lipoxidase in green malt is destroyed during kilning.     

QUANTIFICATION OF MOULD CONTAMINATION IN SULPHURED AND UNSULPHURED MALT

The use of different techniques for assesment of mould contamination in barley and malt is illustrated by reference to an examination of the effect of sulphuring of malt. Reductions in levels of mould contamination were detected in sulphured malts, compared with corresponding unsulphured controls, using direct and dilution plating techniques. Viable counts of wild yeasts, bacteria and thermophilic actinomycetes were also lower in sulphured malts.     

BARLEY COMMITTEE REPORT 1976/1977 SEASON

The Barley Committee, the constitution and activities of which have already been described,¹ is one of the Technical Committees of the Institute of Brewing. It has been decided that it would be useful to publish more widely a summary of the annual results of the Committee's investigations. Since this is the first such report the section of varietal constants and malting grades includes recalculated results for all the varieties currently on the list recommended to farmers by the National Institute for Agricultural Botany (NIAB). In future years recalculations will be done only for those varieties on or just promoted from the Provisional Category.     

BARLEY AND MALT TANNINOGENS AND BEER QUALITY

Anthocyanogen and catechin contents (tanninogen values) were determined for ten two-row and thirteen six-row barleys and for their corresponding malts. Four barley-malts were then selected for brewing, one with high, one with low, and two with intermediate tanninogen contents. The brews were made using bottom-fermenting (lager) as well as top-fermenting (ale) yeasts, both at 50–55° F. and at 68° F. The quality of the beers, as expressed by standard analyses and flavour evaluation, is discussed in the light of the tanninogen contents of the barleys and the different brewing parameters (yeast type and fermentation temperature).     

RELATIONSHIPS BETWEEN MILLING ENERGY AND HOT WATER EXTRACT VALUES OF MALTS FROM SOME MODERN BARLEYS AND THEIR PARENTAL CULTIVARS

Determinations of hot water extract values of malts of some modern barleys and their parental cultivars correlated well (r = ?0.71) with milling energy estimates made on ungerminated grain. This confirms previous findings that these grain attributes are negatively correlated over different sites and growing seasons. Three types of barley endosperm can be distinguished on the basis of milling energy determinations. Most barley cultivars that are difficult to malt or are classified as feed barleys have high milling energy values (ranging from 370 to > 400 mg trace weight). This includes a number of currently recommended cultivars with Hordeum laevitigum in their pedigree. A second endosperm type has significantly lower milling energy values than the feed barley group (ranging from 330 to 355 mg, trace weight); barleys in this category also produce malts with high hot water extract values, e.g. Wing, Proctor and Berac. All of these barleys have one of the sister lines, Kenia—Opal—Maja in their ancestry. The third endosperm type with a loosely-structured ‘mealy’ endosperm has very low milling energy values (280 to 315 mg, trace weight) and includes the cultivars Ark Royal, Triumph and Keg, which give very high hot water extracts from their malts. All of the barleys in this group have the European malting barley Kneifel (also with a very low milling energy) in their pedigree. The results strongly indicate that hot water extract values of malts of current European cultivars are mainly due to the milling energy attribute of the endosperm, or are closely linked to it. This endosperm attribute has been selected through pedigree crossing or in barley collections, from just a few older malting quality cultivars. Evidence that this attribute is not linked to Hordein protein patterns controlled by the hor 1 and hor 2 loci on chromosome 5, is also presented .     

RAPID PREDICTION OF MALT HOT WATER EXTRACT BY NEAR INFRARED REFLECTANCE SPECTROSCOPY STUDIES ON BARLEY

In recent years there has been an increasing awareness of the need for rapid screening tests for malting quality in barley. An infrared reflectance instrument has been calibrated against malt hot water extract (HWE). Results suggest that this type of instrument can be used to estimate HWE on barley and that this might provide a suitable screening method for use in a breeding programme. Greater accuracy is achieved if separate calibrations are made for winter and spring barleys and the correlation coefficients with HWE were 0.70 (n = 168) and 0.82 (n = 134) respectively.     

BARLEY AND MALT ANALYSIS—A REVIEW

This review describes the developments in barley and malt analysis since 1960, the suitability of analyses commonly used at present, and changes which are likely to occur in future. The review is not restricted to analyses suitable for brewers and distillers but also discusses methods used in the control of malting and in the selection of barley for malting.     

AMYLOLYSIS OF LARGE STARCH GRANULES FROM BARLEYS IN RELATION TO THEIR GELATINISATION TEMPERATURES

Large starch granules, prepared from a range of barley samples, show considerable variation in their susceptibility to attack by α-amylase at 65°C. Susceptibility is not correlated with their protein content, amylose/amylopectin ratio or gelatinisation temperature as measured by loss of birefringence. It does correlate with gelatinisation as measured by swelling of the granules or their staining with Congo Red. When granular expansion is taken as the measure of gelatinisation, the more resistant starches show gelatinisation curves displaced to higher temperatures.     

VARIATION IN THE BIOCHEMICAL COMPOSITION OF ACID EXTRACTS FROM BARLEYS OF CONTRASTING MALTING QUALITY

Acid extracts from barleys of poor malting quality were characterized by high viscosity caused by enhanced concentrations of high molecular weight carbohydrates of which more than 80 per cent was β-glucan. Up to 67 per cent of the β-glucan in these barleys was soluble in the acid extracting solution. In contrast, only about 25 per cent of the β-glucan in good malting barleys was soluble, resulting in extracts having low viscosity. No evidence was found for autolysis in any of the extracts, and extracts from good malting varieties were characterized by high concentrations of fructose and sucrose. Protein concentration in the extracts varied little, although the protein content of the barleys ranged from 9·1 per cent to 15·4 per cent. Soluble protein has no effect on extract viscosity or the gel filtration properties of the carbohydrates. Some quantitative variation in acid-soluble and salt-soluble proteins was seen after electrophoresis on polyacrylamide.     

THE MALTING QUALITY OF SOME SPRING BARLEY VARIETIES GROWN IN ENGLAND AND WALES BETWEEN 1880 AND 1980

The malting behaviour of fifteen barley varieties widely grown between 1880 and 1980 has been compared using material grown at two sites in England in 1980. All the varieties examined were considered to be of malting quality at their time of widespread commercial use. Varieties introduced after 1950 gave higher Hot Water Extracts (mean 74·7%) than varieties introduced before 1950 (mean 71·0%), and when the yield data were included to calculate the yield of extract/ha the post-1950 varieties were found to exceed the older varieties by 48·7%. The Kolbach Index of the modern varieties was higher, although there was no evidence of an increase in cold water extract.     

ISOLATION,PURIFICATION AND ELECTROPHORETIC PROPERTIES OF AN α-AMYLASE FROM MALTED BARLEY

An α-amylase component from malted barley was isolated and purified using aqueous extraction at pH 8·0, heat treatment of the extract at 70°C, specific precipitation with glycogen and ion exchange chromatography on carboxymethyl (CM) and diethylaminoethyl (DEAE) cellulose. The enzyme preparation was shown to be pure by disc electrophoresis at pH 8·9 and iso-electricfocusing on polyacrylamide gel in a pH 4–8 gradient.     

A RAPID AND SIMPLE METHOD FOR THE DETERMINATION OF STARCH AND β-GLUCAN IN BARLEY AND MALT

A simple and precise method suitable for the routine determination of starch and β-glucan in barley and malt is described. Perchloric acid (50 mM) was used to effect rapid (3 min) and exhaustive extraction of both glucans which were then measured directly from this single extract by specific enzymic hydrolysis of the individual glucans to glucose. The glucose was also measured enzymically. Little or no acid hydrolysis of starch or β-glucan was observed under the extraction conditions used; most or all of the free glucose could be attributed to hydrolysis of sucrose. Complete solubilisation of the gum and hemicellulosic components of β-glucan was achieved. Preincubation of the acid extracts with protease prior to amyloglucosidase digestion resulted in higher measurements (approximately 4% w/w) of starch. The method was used to measure the levels of starch and β-glucan in five varieties of barley with contrasting malting quality, in micro-malts prepared from these samples and in commercial lager and ale malts.     

THE ACTION OF ENDO-β-1,3-GLUCANASES ON BARLEY AND MALT β-GLUCANS

The β-glucan extracted from ungerminated barley with water at 40 °C has a much lower specific viscosity than the corresponding material isolated from a wort prepared at 65 °C from a two-day germinated barley malt. Both glucans are similar in that they are polymers of β-D-glucose, with approximately 74% of the linkages in the β-1,4 configuration and 26% in the β-1,3 configuration. However, the two glucans are not hydrolysed to the same extent either by a partially purified bacterial endo-β-1,3-glucanase or by a homogeneous endo-β-1,3-glucanase from malted barley. The malt glucan is readily hydrolysed, causing a rapid decrease in specific viscosity but with no measurable increase in reducing power, whereas barley glucan undergoes only limited hydrolysis under similar conditions. Thus, different β-glucan preparations from barley or malt may be identical in the proportion of β-1,3 to β-1,4-linkages but the overall arrangement of linkages, and hence susceptibility to enzyme attack, differs according to the source and the method of extraction of the glucan. The molecular weights of both β-glucan preparations and the products of their enzyme hydrolysis have been determined by agarose gel permeation chromatography. A simple model which illustrates the underlying structural relationships of the β-glucans from barley and malt is suggested.