A METHOD FOR THE STUDY OF THE ENZYMATIC-HYDROLYSIS OF STARCH GRANULES

A method for the study of the enzymic hydrolysis of starch granules is described. A solution of alpha-amylase was pumped through a bed of normal or waxy-maize starch in a column, and the eluate was passed through a column of ion-exchanger that retained the enzyme but not the solubilised dextrins which could be analysed further by gel-permeation chromatography. The material released first from the waxy-maize starch granules contained comparatively large proportions of dextrins of d.p. > 3000. Subsequently, maily dextrins were produced from each type of starch with d.p. 50-200 similar to those produced from the gelatinised starches. Dextrins with d.p. approximately 6 were also solubilised in the later stages. The content and the lengths of amylose-like chains within the normal maize granules decreased notably when large concentrations of enzyme were used. These chains were probably not released from the granules and the reaction seemed to be correlated with the enzyme adsorbed on the granules, whereas the solubilised material originated from the amylopectin component.