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Highlights • Mannose polymers content was significantly high in wheat beers. • Mannose polymers in beers might exist as mannan, glucomannan, or both together. • Degree of polymerization was calculated as mannan and glucomannan, respectively. • Mannose polymers content positively correlated well with beer viscosity. Abstract Mannose polymers are important non-starch polysaccharides in beers. In this study, thirty-six beer samples representing three categories based on materials, including all barley malt beer, barley malt with adjuncts beer and wheat beer, were selected to investigate the content as well as its correlation with beer physicochemical indices, degree of polymerization, molecular weight and existent form of mannose polymers. The results suggested that mannose polymers level was significantly high in the wheat beer (156.76 mg/L and 456.50 mg/L calculated as mannan and glucomannan, respectively). Degree of polymerization was 23–47 and 46–162 calculated as mannan and glucomannan, and the molecular weight was 3,744 - 7,632 Da and 7,470 - 26,262 Da, respectively. Average ratio of glucose to mannose in glucomannan was between 1.79 and 1.93 without significant difference among three groups. Mannose polymers possibly exist in mannan, glucomannan or both. The content had significantly positive correlation with the original extract and viscosity of beers. Their correlation coefficients indicated more important influence on beer viscosity than β-glucan. This preliminary study would be helpful for revealing the structure of mannose polymers and its effect on beer brewing as well as human health. [ABSTRACT FROM AUTHOR]

Compositions, molecular characteristics, and rheological properties of the water-extractable polysaccharides from okra were investigated. The proportions of galacturonic acid and monosaccharides in the refined polysaccharides were 62.47% and 13.47%, respectively. The molecular weight distribution of 717.5 kDa in the crude polysaccharides was removed through a purification process. Okra polysaccharides were pseudo-plastic fluids exhibiting shear thinning behavior. The refined polysaccharides had a higher apparent viscosity (332.15 mL g−1) than the crude polysaccharides (294.69 mL g−1), and exhibited a positive linear correlation with the logarithm of the zero shear viscosity between 1.0% and 4.0%, showed an elastic behavior at a stress of 1 Pa over the frequency range of 1–10 rad/s. When the concentration reduced below 2.0%, the refined polysaccharides showed a predominantly viscous response over the same frequency range. The rheology was greatly affected by their concentrations, indicating water-extractable okra polysaccharides have great potential as a thickening agent in food industry. [ABSTRACT FROM AUTHOR]

[Display omitted] • PME, PL and PG were inhibited but not totally inactivated in apple wine fermentation. • CaCl 2 promoted methanol yield and pectin breaking by promoting PME and PL activities. • PME, PL and PG were activated and methanol increased after aging at 4 °C for 30 days. • CaCl 2 retained pectin with Mp of 3.07 kDa, which was degraded mostly in wine I. • Pectin's Mp in group S was split into molecular mass lower than 3 kDa. Understanding pectin structure and pectinase activity was important to control methanol content in apple wine. Therefore, this study compared inoculated fermentation (I), spontaneous fermentation (S) and inoculated fermentation combined with CaCl 2 treatment (I & CaCl 2) to explore their differences in methanol production, pectin peak molecular weight (Mp), and the activities of pectin methyl esterase (PME), pectin lyase (PL) and polygalacturonase (PG). The results showed that the activities of PME, PL and PG were intensively inhibited during fermentation; however, they still retained 3.41–5.84% (PME), 9.46–17.71% (PL) and 9.17–10.31% (PG) of the initial activities after aging for 30 days. Therefore, the methanol content was increased in all three aged wines even aging at 4 °C. CaCl 2 promoted the PME and PL activities, and thus accelerated the methanol production. Because the pectin with Mp 3.07 kDa was retained by CaCl 2 , the highest pectin content was found in wine I & CaCl 2 (160.69 mg/L), which was 95.47 mg/L higher than that in wine I, and 107.03 mg/L higher than that in wine S. In group S, the long lag period allowed pectin to withstand the pectinases inherent in apple juice for a long time, which was conducive to the cleavage of pectin to Mp lower than 3 kDa continuously, its further degradation led to the lowest pectin content (53.65 mg/L) in wine. Hence, inhibiting the pectinases activities, or shortening the aging period would play an important role in decreasing the methanol content in apple wine. [ABSTRACT FROM AUTHOR]

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 [ABSTRACT FROM AUTHOR]

BACKGROUND Arabinoxylans ( AXs) are partially water-extractable polymers that cause problems of viscosity and filterability during beer brewing. This study investigated the effects of Kolbach index ( KI) on water-extractable AXs ( WEAXs). RESULTS KI had positive correlations with extract ( r = 0.845) and free amino nitrogen ( FAN) ( r = 0.958). The contents of malt WEAXs ( WEAXsm), total AXs and wort AXs ( WAXs) were 10.8-11.6 g kg−1, 57.5-60.8 g kg−1 and 137.5-140.5 mg per 100 mL respectively and the corresponding arabinose/xylose (A/X) ratios were 0.52-0.56, 0.55-0.62 and 0.48-0.50. The molecular weight (Mw) ranged from 4.92 × 104 to 6.93 × 104 Da for WEAXsm and from 1.24 × 104 to 2.90 × 104 Da for WAXs. KI had negative correlations with the average degree of polymerization ( avDP) of malt ( r = −0.877) and wort ( r = −0.978). Wort viscosity showed a positive correlation with the Mw of WEAXsm (Mwm) ( r = 0.821). CONCLUSION Increasing KI can promote the degradation of the xylan backbone, while it cannot affect the branching of the polymer chain and the content and Mw of WEAXs. © 2014 Society of Chemical Industry [ABSTRACT FROM AUTHOR]

This research was to explore the distribution and some molecular characterization of arabinoxylan in wheat beer (B), beer foam (BF) and defoamed beer (DB) because of the crucial influences of arabinoxylan on wheat beer and its foam. The purified arabinoxylan from B, BF, and DB were fractionated by ethanol of 50%, 67%, 75%, and 80%. The monosaccharide composition, substitution degree (Ara/Xyl ratio, A/X), and average degrees of polymerization (avDP) of arabinoxylan were investigated. Molecular weight and microstructure were also involved in this study by GPC-LLS and SEM, respectively. Under the same ethanol concentration, the arabinoxylan content in the BF was higher than the other two, respectively, and it was precipitated in BF fraction with 50% ethanol which accounted for 80.84% of the total polysaccharides. Meanwhile, the greatest substitution degree (A/X) and highest value of avDP of the arabinoxylan was found in all beer foam fractions regardless of the concentration of ethanol used. The average degrees of polymerization (avDP) of arabinoxylan displayed a significant difference (p < 0.05) among B, BF, and DB. Furthermore, arabinoxylan presented varied microstructure with irregular lamellas and spherical structures and the weight-average molecular weight (Mw) of arabinoxylan showed the lowest values in BF, while the largest values were shown in DB. Therefore, arabinoxylan was more accumulated in beer foam, especially in 50% ethanol, characterised by greater value of A/X and avDP, as well as lower Mw. It was suggested that the arabinoxylan played important roles in maintaining wheat beer foam characteristics. [ABSTRACT FROM AUTHOR]