Research On Protein And Polysaccharide Distribution Of Cloudy Wheat Beer

Cloudy wheat beer got consumers to chase after because of its fine and smooth foam, fresh and unique flavor, and the appearance of turbidity. As important components of beer, protein and polysaccharide played pivotal roles in beer characteristics. To understand the influence of protein and polysaccharide on beer quality, and provide theoretical reference for industrial production, the content and molecular weight changes of protein and polysaccharide during brewing; the differences of beer foam and beer; the differences of different beers; chill haze of beer, were studied in this research.1 The changes of protein and polysaccharide distribution of cloudy wheat beer during brewingBy sampling following the industrial brewing of cloudy wheat beer, we found that, the extraction of protein and FAN mainly focused on protein resting process. During fermentation, contents of protein and FAN have similar trend: decended violently on D2 and fluctuated gently soon aferwards. The extraction of polysaccharide continued along all the mashing process, and reached the maximum amount at the end of mashing. Wort boiling and cooling process decreased the amount of polysaccharide. Glucose had the highest amount compared with the other four monosaccharides. At the begging of fermentation, the amounts of glucose and mannose decreased significantly, while that of arabinose, xylose and galactose kept changeless. The av DP of WEAX decreased which stated that WEAX decomposed during mashing. The A/X value of WEAX was 0.50 during brewing.By means of SDS-PAGE, we found that the distribution of protein Mw didn’t change during protein resting process. Turning into saccharification, 65 k Da、27 k Da、23 k Da fractions disappeared, while 45 k Da、35 k Da、29 k Da fractions faded away partially. By means of HPSEC, we found that the Mw of protein mainly distributed between 16.8 k Da and 23.7 k Da and 2.1- 7.6 k Da protein fraction was the primary protein during brewing. 7.6- 32.1 k Da protein fraction was the predominant thermolabile protein that decreased during saccharification and boiling. The most abundant polysaccharide component was the 0.37-12.53 k Da fraction. During wort preparation process, the Mw of polysaccharide in wort decreased from 7.17 k Da to 5.32 k Da on the whole, while increased to 15.48 k Da turning into fermentation, and fluctuated gently soon afterwards in maturation. Wort boiling and cooling decreased the amount of 0.37- 38.54 k Da polysaccharide fraction. Yeast used <2.25 k Da polysaccharide fraction for growth and propagation during fermentation.2 The research on protein and polysaccharide distribution of beer and beer foamBy analysising beer and beer foam which were separated by pouring, we found that, the contents of protein, FAN, WEAX of foam were higher than that of beer and defoamed beer. By means of SDS-PAGE, we found that beer, defoamed beer and beer foam had similar patterns of protein Mw, major fractions were 40 k Da, 10 k Da and 5 k Da, minor fractions were 65 k Da, 60 k Da, 45 k Da and 35 k Da. The result of HPSEC showed that the Mw of protein and polysaccharide in beer foam were higher than that of defoamed beer, which indicated that high Mw protein and polysaccharide played important role in beer foam formation and stability.3 The difference analysis of different beersBy analyzing different sorts of beers, Taishan cloudy wheat beer, Valentin wheat beer, Tsingtao Aogute beer, Valentin bock beer, we found that the contents of protein, FAN, WEAX in the two wheat beers were higher than that of Tsingtao Aogute beer. The contents of protein and WEAX in Valentin bock beer were closed to that of the wheat beers, while FAN content was lower.As shown in HPSEC patterns, 2.1- 7.6 k Da fraction was the primary protein in the four beers. The highest protein Mw of the four beers was 18.16 k Da appeared in Taishan cloudy wheat beer, the following were Valentin bock beer(13.80 k Da), Valentin wheat beer(13.12 k Da), Tsingtao Aogute beer(8.50 k Da). The content of >32.1 k Da protein fraction in Valentin bock beer was higher than that of the two wheat beers obviously, while that of Tsingtao Aogute beer was the lowest. The polysaccharide Mw of the two wheat beers were 12.82 k Da and 10.15 k Da, which were higher than that of Valentin bock beer(9.65 k Da) and Tsingtao Aogute beer(4.94 k Da).4 The research on chill haze distribution of different beersDifferent beers were brewed using different malts combination, barly malt beer, barly malt : wheat malt = 1 : 1 beer, wheat malt beer. By extracting and analyzing the chill haze in the three beers, we found that, the chill haze of barly malt beer was composed by 40 k Da, 15 k Da,7 k Da fractions, while that of wheat malt beer was 15 k Da, 10 k Da. > 13.2 k Da protein fraction was the primary chill haze. The higher the add proportion of wheat malt, the larger the Mw of chill haze in beer.