Kaffircorn malting and brewing studies. IV.—The extraction and nature of the insoluble amylases of kaffircorn malts

The α‐ and β‐amylases produced by the germination of kaffircorn may be either soluble or insoluble depending on the variety of the kaffircorn. The insoluble amylases occur chiefly in malts from ‘birdproof’ kaffircorn and sweet sorghum. The amylases of these varieties, unlike the bound amylase of barley, are active in the insoluble state. Proteins, peptone, ethylenediamine, histidine and compounds containing the group —N°C(X)·N— (where X is not oxygen) effect maximum liberation of the insoluble amylases. Partial solution is obtained with salts, surface‐active agents and certain basic substances. The release of the amylases is not a proteolytic process but possibly a desorption from the surface of an insoluble protein.