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The Influence of the Withering Temperature on the Resulting Proteolytic and Cytolytic
C. Mueller, M. Kleinwaechter, D. Selmar and F.-J. Methner

During kilning, the germinated malt has to be dried from moisture contents of 42?48 to 3?6 % to interrupt the growth and to make the malt storable. Therefore, the green malt is firstly dried by blowing air with moderate temperatures between 45?65 ?C through the grain bed. This first of two steps during kilning is called withering and it is important to ensure highest possible enzyme activities in the malt which are mandatory for later brewing process. During withering, the enzyme formation and activities are accelerated and a lot of biochemical reactions, e.g. the enzymatic degradation of cell wall substances hemicelluloses (cytolysis) and protein (proteolysis), occur especially at a stage of still high grain?s moisture content. The withering temperature has a remarkable influence on the final malt quality. After withering, when a moisture content of 10?15 % is reached, the malt is cured at higher temperatures between 75?90 ?C for some hours for pale malt like Pilsener malt.

Descriptors: kilning program, withering temperature, cytolysis, proteolysis, grain layers

BrewingScience Monatsschrift fr Brauwissenschaft, 67 (July/August 2014), pp. 88-95