CHANGES IN THE CONTENTS OP BARLEY PROTEOLYTIC INHIBITORS DURING MALTING AND MASHING

Abstract

Barley contains three types of large-molecular proteolytic inhibitors, viz., inhibitors active against malt endopeptidases, a specific trypsin inhibitor, and a group of inhibitors of microbial proteinases and chymotrypsin. The inhibitors of malt endopeptidases disappear at an early stage of germination, just before the endopeptidase activity begins to increase. The total amount of these inhibitors is so small, however, that the great increase in endopeptidase activity occurring during germination cannot be due to the breakdown of an “equivalent” amount of inhibitors. The contents of the other two types of inhibitor in barley are much higher; they decrease slowly during germination, but high activities are still present in malt. The inhibitors of microbial proteinases are progressively inactivated during mashing. The trypsin inhibitor retains full activity through mashing, but is completely inactivated during boiling and hopping.