制麦对蛋白水解酶活性及氨基氮含量的影响

THE EFFECSTS OF MALTING ON THE PROTEINLYTIC ENZYME ACTIVITY AND AMINO NITROGEN CONTENT

以水溶性大麦蛋白质为底物，测定麦芽蛋白质水解酶活性和α－氨基氮含量。结果表明，绿麦芽与原料大麦相比，蛋白酶活性增长了１０．６倍，但经焙燥，活性降低１９．３％；粗酶液在６０℃以上保温２０ｍｉｎ，即失去活性，但在协定法糖化升温至７０℃之前并未完全钝化。测得１２个麦芽样品的总α－氨基氮（α－ＡＮ）包括５３％～７３％的原始ＡＮ和２７％～４１％的酶解ＡＮ。经过焙燥后由于蛋白水解酶活性和原始ＡＮ损失导致成品麦芽中总α－ＡＮ的减少。

A method was developed to assay the proteolytic enzyrne activity in malt with the barley solubleprotein as substrate for estimating the enzymolytic activity of malt. The enzyme activity was measured interms of free α-amino nitrogen(α-AN) solubilized.The proteolytic activity in green malt increased by 9.6times compared with which in raw barley but decreased by 19.3%after kilning。 The malt proteolytic enzymewas not inactivated thoroughly when the temperature was bellow 70℃ during EBC mashing, though thecrude enzyme was inactivated above 60℃ for 20min。 Total malt α-AN included 53%～73%of the originalAN and 27%～47%of the enzymolytic AN in 12 samples. Loss of proteolytic activity and original AN afterkilning led to the reduction of total α-AN in final malt.