Research On A New Process Of Barley Syrup For Beer Brewing By Holoenzymatic Method

To research the new technology of barley syrup by enzymatic method, the optimum tempreture and pH value ofβ-amylase, promozyme, neutral protease, xylanase,β-glucanase were identified. Using domestic barley as raw material, the preparation conditions of barley syrup was further researched and the new process was also determined. To some extent, new process resolved some problems in the preparation process of barley syrup, such as unsufficient promotion of enzyme preparation, lowα-amino acid-N content and irrationality for saccharide component and Lundin fraction of soluble nitrogen, and systematically expounded the theory and the basis of related technology. The research showed that:1 Through a single factor test, the optimum pH and temperature ofβ-glucanase, neutral protease and xylanase were concentrated in 6.5, 50℃,β-amylase and promozyme for 5.5, 55℃. Accordingly, in order to fully play the catalytic role of these enzymes, the two-step saccharification technology were applied to preparate for barley syrup.2 With the conditions of temperature 100℃and pH 6.5, the effects of enzymes on barley liquefaction under different times were examined. when the amount of enzymes were 15U/g, the optimum time was 40 minutes. Because of reasonable liquefaction, the final raw material using rate was 99.5%.3 In every step of saccharification technology, the effects of liquefaction time, enzymes assemblage and amount of enzymes on barley liquefaction were researched. The optimum enzymes assemblage wereβ-amylase, promozyme, glucoamylase,β-glucanase and xylanase, with their adding amounts 100u/g, 0.2ASPU/g, 7u/g, 2.0u/g and 3.0u/g, respectively. The optimum time in the first step was 2h, while that in the second step was 4h. In this way, the saccharide component of barley syrup was reasonable, and itsβ-glucan and other substances were sufficiently degradated, which eliminated its impact on the beer brewing using barley syrup.4 It was discovered through proteolysis that the problem of low content ofα-amino acid-N in barley syrup can only be resolved when hydrolyze protein ahead of liquefaction , so we advanced new technology of proteolysis: partical protein was hydrolyzed, after liquefaction, protein was hydrolyzed again. Through the new technology, the content ofα-amino acid-N and soluble nitrogen reached to 184.4mg/L and 994.6mg/L respectively, increased by 60% compared with those of the reported, besides the soluble nitrogen had rational Lundin fraction, which meeted the needs of beer brewing. The optimal conditions of hydrolyzation were as follows: the addition of neutral proteinase during prehydrolysis was 100u/g, the time was 30minutes, while the addition of neutral proteinase was 50u/g during saccharification.5 The preliminary experiment of beer brewing were carried out by substituting 30% of malt wort with barley syrup. The quality indexes of the products of beer were qualified to GB- 4927-2001.