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Arabinoxylans (AXs) from wheat malts potentially affect beer quality and production. β- d-Xylosidase is a key enzyme that degrades the main chains of AXs to produce xylose. This study performed a partial characterization of β- d-xylosidase from wheat malts. The optimal temperature was 70 °C and the enzyme exhibited excellent thermostability, that is, residual activities were 92.6% at 60 °C for 1 h. The enzyme was stable over a pH range of 3.0–6.0 and showed optimum activity at pH 3.5 and 4.5. Kinetic parameters Km and Vmax of wheat malt β- d-xylosidase against p-nitrophenyl-xyloside were 1.74 mmol L−1 and 0.76 m m min−1, respectively. The enzyme activity was severely inhibited by Cu2+, moderately inhibited by Mn2+, Mg2+, Al3+, Ca2+, Ba2+ and Na+ and mildly inhibited by Fe3+ and Fe2+. The partial enzymatic characterization achieved in this study can be used as a theoretical basis for purifying β- d-xylosidase from wheat malts. Copyright © 2015 The Institute of Brewing & Distilling

To investigate the changes in protein in cloudy wheat beer (CWB) brewing, the molecular weight (Mw) of protein components in wort, fermenting wort, beer and beer foam were analysed by high-performance size-exclusion chromatography. It was found that the Mw of protein during brewing was mainly distributed between 100 and 0 kDa. From mash to the final beer, the most abundant protein component was the 7.6–2.1 kDa fraction, which occupied more than 40% of the total protein. The extraction of soluble protein from malts into wort mainly focused on the protein rest process, where the 100.0–32.1 and 7.6–2.1 kDa fractions increased significantly. In addition, the 100.0–13.2 kDa fraction was the predominant thermolabile protein that decreased during lautering and boiling. The dominant protein constituting the fine coagulum, the 100.0–13.2 kDa fraction, also decreased during fermentation and maturation. The CWB, defoamed CWB and CWB foam had similar protein Mw distributions, while the CWB foam concentrated much more protein and the 7.6–2.1 kDa fraction was the major protein in the CWB foam. Copyright © 2015 The Institute of Brewing & Distilling

In this study, the relationships between protein degradation, enzyme activities and quality of EBC (European Brewery Convention) wort were investigated. The Kolbach index of wheat malt at 37.6–42.7% was found to be suitable for acquiring higher enzyme activities. A globulin increase was the main factor that promoted the activities of the degradation enzymes. Strong synergistic activity was observed among the polysaccharide degradation activities of enzymes [α-amylase, β-amylase, β-glucanase, β-d-xylosidase and β-(1,4)-endoxylanase]. Increased protease production improved the Kolbach index of a wheat malt, that is, promoted the degradation of gliadins into albumins and globulins. Increased albumins and globulins resulted in increased enzyme activity for polysaccharide degradation. Increased enzyme activities demonstrated synergistic actions that ultimately promoted the quality indices of an EBC wort, including extract yield, α-amino nitrogen, acidity and chromaticity. Copyright © 2014 The Institute of Brewing & Distilling

Sulphur dioxide (SO2) is the main additive in grape wine production and cannot be eliminated by simple distillation from the base wine, lees or fermented pomace. This research was conducted to confirm the effectiveness of calcium oxide, powdered activated charcoal and hydrogen peroxide on SO2 reduction in distilled grape spirits using a double distillation method. Three treatments were conducted on the first distillate. Each method was assessed for its effectiveness on SO2 reduction and its influence on the volatile compounds present, which were analysed both by GC and sensory evaluation. The total residual SO2 content in the second distillate, which had been treated with calcium oxide, was about 2.00 mg L−1. The value was below 1.00 mg L−1 for the activated charcoal and hydrogen peroxide treatments. The calcium oxide treatment was the most convenient method, when compared with the other two treatments, but it also caused the largest decrease in acids and esters. The activated charcoal-treated distillate had the highest sensory evaluation. However, there were some drawbacks, such as the loss of esters and a higher cost for temperature maintenance (70°C for ~12 h). The hydrogen peroxide treatment resulted in the lowest pH and most of the volatile compounds were retained, but the sensory evaluation was second to the activated charcoal treatment. Copyright © 2013 The Institute of Brewing & Distilling

Characteristics of lipoxygenase (LOX) in wheat malt with various conditions, including optimum temperature, pH and thermostability, were studied. The results showed that the optimum temperature was 35 °C, the optimum pH value was 6.8 and the deactivation temperature was 70 °C. With increasing temperature, thermal stability was reduced. The LOX activity of dry wheat malt showed a significant positive correlation with filtration time (R = 0.979, p

In this study, the malting performance of six traditional Chinese wheat varieties was evaluated. The effects of protein content on wheat endosperm composition and the malt quality were studied. The β-glucan in the malt showed a positive correlation (r = 0.806, P

The content and the molecular weight distribution of wheat water-soluble proteins during malting were determined. Also, the relationships between wheat malt characteristics and water-soluble protein molecular weight distributions were studied. The water-soluble protein content was found to increase during malting and the increment was most significant on the first and second days. The molecular weight distribution of the wheat water-soluble protein was analysed by high-pressure size exclusion chromatography (HPSEC) and sodium dodecyl sulphate–polyacrylamide gel electrophoresis (SDS-PAGE) methods. The HPSEC method showed that the content of all six molecular weight fractions (>24.4, 9.8–24.4, 3.9–9.8, 2.5–3.9, 0.4–2.5 and 24.4, 9.8–24.4 and 3.9–9.8 kDa fractions showed a declining trend during steeping but an increase during the first 2 days of germination. The content of the 9.8–24.4 kDa fraction increased during the process of kilning. Wheat had a high percentage of the >24.4 and 9.8–24.4 kDa fractions, while wheat malt had a high percentage of the 2.5–3.9 and 0.4–2.5 kDa fractions. The molecular weight fractions of the water-soluble protein had negative correlations with wheat malt viscosity and positive correlations with wheat malt extract. The SDS-PAGE analysis showed that the band of the 60 kDa water-soluble protein faded, while the bands of the 56, 44 and 12–15 kDa water-soluble proteins became darker during malting. Copyright © 2014 The Institute of Brewing & Distilling