Effect of electron-beam irradiation on the safety and quality of Fusarium-infected malting barley

Utilization of Fusarium-infected barley for malting may lead to mycotoxin production during malting and decreased malt quality. Electron-beam irradiation may prevent safety and quality defects and allow use of otherwise good quality barley. We evaluated electron-beam irradiation for preventing Fusarium growth and mycotoxin production while maintaining barley-malt quality characteristics. Four barley lots with varying deoxynivalenol (DON) concentrations were irradiated at 0, 2, 4, 6, 8, and 10 kGy. Treated barley was malted in a pilot-scale malting unit. Barley and malt were analyzed for Fusarium infection (FI), germinative energy (GE), aerobic plate counts (APC), mold and yeast counts (MYC), and DON. Malt quality parameters included malt extract, soluble protein, wort color, wort viscosity, free amino nitrogen, alpha-amylase, and diastatic power. FI, APC, and MYC decreased in barley with an increase in dosage. The APC and MYC for malts from barley exposed to 8–10 kGy were slightly higher than in other malted samples indicating that irradiation-resistant microflora could flourish during malting. Barley GE significantly decreased (3–15%) at 8–10 kGy. Although irradiation had no effect on DON in raw barley, DON decreased significantly (60–100%) in finished malts prepared from treated barley (6–10 kGy). Malt quality parameters were slightly affected by electron-beam radiation. The results suggest 6–8 kGy may be effective for reducing FI in barley and DON in malt with minimal effects on malt quality.     

CONTROLLING MALTING LOSSES WITH ANOXIA,CARBON DIOXIDE,AND SULPHUR DIOXIDE

Micromalting trials were used to evaluate the effectiveness of various treatments with anaeroblosis, carbon dioxide or sulphur dioxide in controlling malting losses with grain treated with gibberellic acid. Periods of increasing anoxia, with carbon dioxide accumulation as in Kropff malting, produced malt with a reduced malting loss and a lower hot water extract than control malting. Covering germinating barley with atmospheres containing various partial pressures of carbon dioxide reduced malting losses, but the resulting malts were usually inferior in quality to the controls. Sulphur dioxide gas, applied to moist germinating barley three days after casting, reduced malting losses by almost 3%, and increased the hot water extract by about 3 lb./Qr. relative to control malts. The treated malt occupied less space than the control, and the heat output was reduced. Sulphur dioxide treatment and only 4 days' germination produced a malt in high yield, with an extract identical to that of a control malt germinated for five days. The sulphur dioxide malts yielded worts with lower pH and higher soluble nitrogen values than the control and the fermentability of the worts was normal.     

A SIMPLE AND RAPID TEST FOR ASSESSMENT OF ENDOSPERM PROTEIN MODIFICATION DURING MALTING*

A simple test has been developed for the quantitation of endosperm protein modification in malts. Barley meals or ground malts were extracted with a suitable solvent and the clarified hordein extract diluted into an appropriate precipitant. Of a variety of extractants and precipitants investigated, 1M urea-1% (v/v) mercaptoethanol and 1M sodium chloride were respectively found to be most suitable. Under these conditions a turbid suspension forms; the turbidity of extracts decreased progressively during malting. Turbidity was due to selective precipitation of a specific group of “B” hordeins. In an analysis of nine varieties differing in malting qualities, a significant correlation between the reduction in extract turbidity and cell wall modification (Calcofluor staining) was observed at 48 hours' malting. In addition, for each variety examined, protein modification occurred about one day before carbohydrate modification. Analysis of commercial malts and several samples of selected cultivars from regional trials found good correlations between malt turbidities and percent malt extract and Kolbach index. The test is rapid (10–90 mins) and can be used to screen large numbers of samples; since it is simpler than alpha—amino nitrogen or Kolbach index determination, it may be of use in analysis of malts for protein modification.     

NEW MASHING SYSTEM FOR DETERMINATION OF LABORATORY EXTRACT

The method of preparation of laboratory wort by the Tepral mashing system provides a clear improvement in the evaluation of industrial malts and in the optimization of malting procedures. The equipment required is simple and easy to operate. The use of the method has shown significant differences in terms of both wort viscosity and extract yield between malt from 2-row spring barley (variety Carina) and malt from 2-row winter barley (variety Sonja), produced under identical industrial conditions: the Sonja malt gave fewer good results for finely ground malt than did the Carina malt.     

Effect of hot water treatments on the safety and quality of Fusarium-infected malting barley

Utilization of Fusarium-infected barley for malting may lead to mycotoxin contamination of malt and decreased malt quality. Hot water treatments may prevent or reduce safety and quality defects and allow use of otherwise good quality barley. We evaluated hot water treatments for preventing Fusarium growth and mycotoxin production while maintaining barley-malt characteristics. Four barley lots with varying deoxynivalenol (DON) concentrations were hot water-treated at 45 or 50 degrees C for 0, 1, 5, 12, and 20 min. Treated barley was malted in a pilot-scale malting unit. Barley and malt were analyzed for Fusarium infection (FI), germinative energy (GE), aerobic plate count (APC), mold and yeast count (MYC), and DON. Malt quality parameters included malt extract, soluble protein, wort color, wort viscosity, free amino nitrogen, alpha-amylase, and diastatic power. Significant decreases in FI occurred within 1 min at both 45 degrees C (41-66%) and 50 degrees C (51-69%) in all barley samples. Significant reductions in APC (1.0-1.8 log) and MYC (1.7-1.8 log) in barley were observed after 5 min at both temperatures. The largest reductions for DON were observed in malts prepared from barley treated with hot water at 45 degrees C (79-93%) and 50 degrees C (84-88%) for 20 min. GE and most of the malt quality parameters were only affected when barley was treated at 50 degrees C for 12 and 20 min. The results suggest that hot water treatments may offer the potential for treating mildly FHB infected malting barley.     

采用PCR-RAPD技术鉴定16种北美啤酒大麦

本文采用PCR—RAPD技术，从浸泡过的成熟胚乳中提取DNA，成功地鉴定了在北美种植的五种二棱啤酒大麦和十一种六棱啤酒大麦。与从叶芽中提取DNA的结果比较，表明该方法简单快捷而又准确可靠。     

Effects of nitrogen application on malt modification and dimethyl sulfide precursor production in two Japanese barley cultivars

BACKGROUND: Nitrogenous components have a great influence on both malt and beer qualities. Barley storage proteins are degraded during the germination process, in which amino acids and small peptides are released. Some of these compounds relate to dimethyl sulfide precursor production in the malting process. In this study, barley and malt qualities were investigated using two Japanese barley cultivars, Sukai Golden and Mikamo Golden, with several different nitrogen (N) treatments. RESULTS: Nitrogen top‐dressing treatments efficiently increased N and sulfur (S) concentrations in grains. A difference in malt modification was induced by these treatments without any change in protease activity in malts. S‐Methyl methionine (SMM) concentration in malt of Sukai Golden with low‐N treatment was 1.8–2.1 times higher than that with higher‐N treatments. Methionine concentration in malts was not significantly affected by N treatments of both cultivars, while grain S level was not consistent under any treatments. CONCLUSION: Results show that low‐N treatment increases SMM concentration in malts despite major S‐containing amino acids of malts being not highly affected by the difference in nutrient status of grains. Further investigations are necessary into aspects of both metabolic profiles in barley germination and SMM degradation in the kilning process. Copyright © 2008 Society of Chemical Industry     

NEW BARLEY VARIETIES IN CONTINENTAL EUROPE*

Breeding and cultivation of high quality malting and brewing barleys still play an important part on the Continent. In each country of the former six of the Common Market, there are Institutes and Associations dealing with the selection and promotion of suitable strains. In Germany, examination of new hybrid strains is carried out by micromalting very small samples (2 × 100 grams). If larger quantities of defined material are available, malting of 1 kg takes place; the malt obtained is then processed within a micro-brew. By such means it has been shown that recently introduced barley types such as Villa, Carina, Columba and Ortolan are at least equal to the former well-known types Wisa, Bido and Union. Desirable agricultural properties were improved without impairing the extract level of malts and the enzymic capacity could be raised. The small-scale brews showed favourable results in the distribution of nitrogenous substances and level of polyphenols and with respect to foam stability and flavour properties. A mathematical evaluation has indicated the influence of variety on extract and protein content of barleys, though the growth area is also of considerable importance. Relationships between variety and polyphenols and gums have been found as well as an influence on sugar composition and amino acid level in worts and beers. A study of naked barley and winter barley has shown that these types, owing to various deficiencies, are unlikely to become important.     

Changes in Germination and Malting Quality During Storage of Barley

To increase brewing yield and efficiency, malts with high extract values, high enzymic activities and good modification are essential. To produce malt that meets these requirements, the barley employed must have minimal post‐harvest dormancy and be able to germinate vigorously. The aims of this study were to determine the extent to which some Australian barley varieties changed during post‐harvest storage, how these changes influenced germination characteristics, enzyme production and malt quality, and, of the germination tests examined, which gave the best indication of a barley's malting potential. Four commercially grown barley samples were obtained, one from Tasmania and three from Victoria. Each sample was stored at room temperature for one year. At monthly intervals, samples were taken and placed at ?18°C. The germinative energy (GE) and germinative index (GI) of these samples were measured. Samples were also micro‐malted and the quality of the malt was assessed using standard EBC methodology. Storage at room temperature positively influenced the germination characteristics of all samples, with concomitant improvements in hydrolytic enzyme production during malting and in a number of malt quality parameters. It was found that, of the germination tests examined, the GI consistently correlated with enzyme activities during malting and with various malt quality parameters thus indicating that the GI is a good indicator of malting potential.     

Effect of sample size on the micro-malting of barley

Steep moisture, malt moisture, malt yield, malt extract and extract yield were determined when barley samples in the range 5–100 g were subjected to the same malting procedure. Smaller samples took up more water during steeping, and produced malts with a higher moisture content. This led to a lower malt yield and a higher malt extract and extract yield for small samples. The malt moisture, malt extract and extract yield determinations on 5 g samples were of similar precision to those on 100 g samples, while the steep moisture and malt yield were more variable with the small sample.     

Mechanisms of Malt Extract Development in Barleys from Different European Regions: II. Effect of Barley Hordein Fractions on Malt Extract Yield

To examine environmental differences between southern and northern European malting barleys, particularly relating to protein and hordein influences on malt extract development, samples of the malting barley cultivar Alexis, from the Nordic countries and from the Iberian Peninsula, were used. Fractionation of hordeins was carried out on barley grams, prior to micromalting and malt analyses, using high performance liquid chromatography (HPLC). Different mechanisms for extract development, in malting barleys from the North and South of Europe, have been demonstrated. Barley protein content determined a significantly greater decrease in malt extract in the Nordic samples, compared with those from the Iberian Peninsula, while apparent final attenuation showed a more pronounced positive association with extract in the South than in the North. B‐hordein was associated with a significanlty greater decrease in malt extract in the Nordic compared to the Mediterranean samples.     

法麦Vanessa制麦特性的探讨

法麦Vanessa是优质的啤酒大麦,但该品种大麦不同于国麦和其它进口大麦,制成的麦芽通常粘度和葡聚糖较高,因此,制麦时要根据大麦特性适时制定相应工艺,才能获得优质麦芽。     

THE VISCOSITY OF WORTS IN RELATION TO THEIR CONTENT OF β-GLUCAN

A procedure is given for assessing that proportion of wort viscosity which is attributable to β-glucan. Worts obtained from unkilned samples of malt which have been processed for 54 or 72 h show enhanced viscosity. This is principally due to β-glucan although the contribution of other constituents, absent from the wort of fully modified malt, is of significance. Barley variety is shown to have a pronounced effect on wort viscosity. Insoluble β-glucan is brought into solution in mashes at 65° C. The β-glucan isolated from malt which has been inactivated using aqueous ethanol prior to extraction at 65° C, is of higher specific viscosity than that isolated from control worts prepared at the same temperature. The introduction of a rest by mashing initially at 40° C results in the production of wort of lower viscosity, a decrease in the β-glucan content of the wort and a reduction in the specific viscosity of the β-glucan. There is no apparent relationship between the endo-β-glucanase content of the malts and either the viscosity of derived worts or the degree of breakdown of β-glucan which occurred during malting and mashing. Abrasion of barley, which is a factor assisting the distribution of enzymes during malting, acts to reduce wort viscosity.     

Malting Behaviour of Barleys Grown in Canada and Spain as Related to Hordein and Enzyme Content

To continue our effort to analyse the genetic (varietal) and environmental (sites and years) effects on malting quality of barley, we have field‐tested four barley varieties, two‐ and six‐rowed, European and North American, in Spain and Canada in 1998 and 1999. The Spanish trials were autumn‐sown whereas the Canadian ones were spring‐sown. Barley grain was analysed for total protein and hordein contents and micromalted. Canadian‐grown barleys had significantly lower contents of grain protein and all‐three hordein fractions than the Spanish ones. They also had lower malt respiratory losses, wort β‐glucan and viscosity but lower fine‐ and coarse‐ground malt extract yield, friability, free amino nitrogen, Kolbach index, α‐amylase and diastatic power. In other words, the Canadian‐grown barleys, despite showing lower protein and hordein contents, produced malt of inferior quality than their Spanish counterparts, which, overall, produced higher quantities of degrading enzymes (amylolytic, proteolytic and cytolytic) during germination, thus being able to attain higher extract yield levels.     

USE OF THE HAGBERG FALLING NUMBER APPARATUS TO DETERMINE MALT AND BARLEY QUALITY

The Hagberg Falling Number measurement, widely used in the milling industry for assessing the baking quality of wheat flour, has been modified and used as a rapid mashing technique to assess malt quality. Barley Malt flour is mixed with cold mashing liquor containing 0.1% calcium chloride and 15 mM beta-mercapto-ethanol. The slurry is heated and mixed by the Falling Number apparatus, and the starch is gelatinized. After one minute of heating/mixing the stirring rods are raised and released. As the gelatinized starch is hydrolysed by amylases, the viscosity of the slurry decreases allowing the stirring rods to fall. The time taken for these rods to fall a fixed distance is called the Falling Number. A relationship has been determined between the Falling Number obtained for a malt and the quality of the malt. Poor quality malts had a high Falling Number (e.g. >200s) whilst good malts had a low Falling Number (e.g. <150s). The correlation coefficient between Falling Number and Hot Water Extract (IOB coarse grind) was ?0.89, and between Falling Number and Friability was ?0.96. These good correlations indicate the measurement was influenced by the degree of endosperm modification. Being a mashing technique, however, the Falling Number was also influenced by other factors which influence mashing such as enzyme complement and water binding. This technique has the potential to measure malt quality using a commercial apparatus more rapidly than present malt analyses. No significant relationship could be determined between the Falling Number and the malting quality of barley.     

THE INSTITUTE OF BREWING ANALYSIS COMMITTEE REVISED METHODS OF EXTRACT DETERMINATION

Following a Brewer's Society request to consider a change from a standard Miag Disc Mill setting of 0·5 mm to one of 0·7 mm the Analysis Committee has re-evaluated the determination of hot water extract. It is recommended that from 1st December 1979–1. A Miag Disc Mill setting of 0·7 mm be adopted for grinding malt for the determination of hot water extract. 2. Where an estimate of the fine/coarse grind hot water extract difference is required, mill settings of 0·2 mm and 0·7 mm respectively should be used. The reproducibility of this procedure is adequate to separate malts into classes with high and low values but analytical tolerances cannot be recommended for commercial transactions. Revised methods for setting the Miag Disc Mill and for determining the hot water extract of fine and coarse ground malts are given in Appendix I. It is proposed that all mashes should be made in stainless steel beakers, the use of the standard brewers' mash flask being limited to making the mash to the correct volume at the end of the determination. It is recommended that, from 1st December 1979, the 0·7 mm Miag Disc Mill setting should replace also the 0·5 mm setting in all Recommended Methods for coloured malts, dark malts, roasted barley and unmalted grain. It is further recommended that from 1st December 1979 all specific gravity determinations for laboratory extracts of malt, coloured malt, dark malt, roasted barley, unmalted grain, sugars, syrup, caramel and spent grains should be made at 20°C.     

Malt characteristics of sorghum vulgare varieties from ghana

Two local varieties, a white type and a red type, of Sorghum vulgare cultivated in Ghana were malted, using a micro-malting method, and their malt characteristics studied and compared to that of a commercial barley malt. The optimal germination time, at 30°C, to produce a good malt of high diastatic power and extract from local varieties of these varieties was 4-5 days. The local varieties were also found to have high diastatic activities of between 55 and 68% of the commercial barley malt. Hot-water extracts of the well malted sorghum varieties were also found to have higher and sustainable amounts of free amino nitrogen than the commercial malt. The hot-water extracts of sorghum malts were lower than the commercial barley malt, yielding about 66-77% of the barley malt, but contained a higher glucose to malt ratio. In terms of varietal superiority, the white sorghum yielded higher malt extracts than the red type.     

AMMONIUM PERSULPHATE IN MALTING: CONTROL OF NDMA AND INCREASED YIELD OF MALT EXTRACT

Application of ammonium persulphate to barley just beginning to germinate, allows the production of malts with a low NDMA content, even when high NO, conditions are used during kilning. No other palliative, such as sulphuring, is required. Like bromate, the persulphate reduces root growth and malting loss but, unlike bromate, it does not restrict nitrogen modification. It appears to enhance the effect of gibberellic acid. Use of persulphate, therefore, not only gives a greater yield of malt but can also give more extract from a given weight of malt. It may also facilitate the malting of inferior barley samples.     

MALTING QUALITY OF SRI LANKAN VARIETIES OF SORGHUM

The malting quality of Sri Lankan sorghum was studied using seventeen varieties. These varieties represented four colour categories (brown, yellow, pink and white) of sorghum found in Sri Lanka. The main criteria used for the assessment of malting quality in this study were the malting loss, diastatic power, liquefying power and the quantity of extract. Malting losses of these varieties were somewhat higher than those encountered in malting barley. However, they appeared to depend partly on the malting conditions. The diastatic powers and liquefying powers observed in this study were inferior to those observed with barley malt. However, with some varieties they appeared to be adequate for the purpose of mashing, as indicated by the high extract values obtained, which were comparable with those of some barley malts. Extract values of the four colour categories varied considerably and the best values were observed with the yellow and pink varieties and some varieties of white. Brown varieties in spite of their comparatively high diastatic powers and liquefying powers gave very little or no extract on mashing.