Research On Reducing The Barley Material Consumption During The Malting Process

The barley material is consumed during the process of malt steeping, germinating,kilning and grubbing. The consumption is malting loss which is about9%~14%of the barleydry weight. Reducing the malting loss can not only reduce the malting cost, but also reducethe discharge of CO2, which will make remarkable economic and environmental benefits. Weshould reduce the malting loss in the condition of ensuring the malt quality.During the process of malting, partial carbohydrate materials of barley are metabolizedto H2O and CO2in the tricarboxylic acid cycle. The consumption is respiration loss, which isthe primary source of malting loss. Malate dehydrogenase (MDH) is a key enzyme in thetricarboxylic acid cycle. If the activity of MDH can be inhibited, the consumption ofcarbohydrate material would be reduced, and the malting loss would be reduced.In this research, Sebastian barley and Chinese barley were used as test samples formalting, we added different concentrations of Na+, Ca2+and Zn2+in the last steeping and usedblank group as control group. For finding out which metal ion can reduce the activity ofMDH and malting loss, and have no negative effect on the activity of α,β amylase andpectinase, we determined the effect of Na+, Ca2+and Zn2+on the activity of MDH, α,βamylase and pectinase in the process of barley germination, and determined the respirationloss and malting loss in the end of malting. We analyzed the inhibition type of metal ion bykinetics of enzyme-catalyzed reactions. We determined the quality parameters of malt, andfound out the optimal group which had the lowest malting loss and best quality parameters.The result showed that treatment groups treated with Na+and Ca2+increased therespiration loss and malting loss, so treatment groups treated with Na+and Ca2+in the laststeeping were not feasible in this research. The results of treatment groups treated with Zn2+showed that, Zn2+promoted the activities of α,β amylase and had seldom action to pectinase,the activity of MDH was inhibited by Zn2+, and the inhibition type of Zn2+wasnoncompetitive type. The malting loss was reduced during the process of malting whenSebastian barley treated with0.50,0.75,1.00mmol/L Zn2+and Chinese barley treated with0.75,1.00mmol/L Zn2+, the treatment group of1.00mmol/L Zn2+had the lowest malting loss and best quality parameters, the Sebastian barley treatment group’s malting loss reduced by1.47%, and the Chinese barley treatment group’s reduced by1.23%.