Effect Of β-amylase From Jiangsu Barley Malt On The Filterability

Barley malt is one of the main raw materials for beer brewing, and the quality of maltdirectly determines the quality of the final beer. However, the poor filtration performance canprolong beer production cycle, increase production costs, cause beer turbidity and decreasestability. In order to find the factors that might cause the poor filtration performance of maltproduced from some barley cultivars grown in Jiangsu province, the proteomes of Jiangsu andimported barley malt were compared by employing two-dimentional electrophoresis (2DE)and MALDI-TOF-TOF tandem mass spectrometry approaches. Glycometabolism-relatedproteins and pathogenesis-related proteins were of the significant differences between the twomalts, and in all of these differential proteins, β-amylase was found to be more significantdifference between them. And the enzymatic activity of β-amylase in Metcalfe barley maltwas30%higher than that of Daner. Therefore, β-amylase was proposed to be related with thefilterability of malt.The β-amylase was purified from Daner barley malt by ammonium sulfate precipitation,anion exchange chromatography and gel filtration chromatography. The specific activity ofthe purified β-amylase was1409.9U/mg, the activity increased by28.4folds and the finalrecovery rate of the total activity was11.5%. The optimum pH of the purified β-amylase was5.5, and the optimum temperature was50℃. It was relatively stable in a buffer solution of pH4.0~7.5and incubated at40~50℃. Ca2+had significant activating effect on the activity ofβ-amylase, while Fe2+had the most significant inhibitory effect. The parameter of enzymekinetics (Km) was5.37mg/mL.The purified β-amylase was then added into mashingprocess of Dan’er malt. The resultsshowed that the β-amylase addition would significantly compensate for the filterability defectof barley malt. When120U/g of β-amylase (about1.5-fold of the different activity ofβ-amylase between Dan’er and Metcalfe malts) was added, the filtration rate of wortincreased by40%, the turbidity and viscosity decreased by72%and14%, respectively. Theactivityof β-amylase in the mash reached maximum under the conditionof60℃, pH5.8, fnegrist and stirring during the mashing. By changing the mashing process, it was found that thefilterability of malt was improved to keep the mash maintained at62℃during mashing.