Characterization of Chemically Modified Potato Starch Films Through Enzymatic Degradation

Abstract

The present investigation was undertaken to characterize the biodegradation pattern of chemically modified starch films. Chemically modified starch films obtained by esterification of the hydroxyl groups of the polysaccharide have shown lower water sorption than native starch films, being therefore more attractive for a number of processing applications. However, no systematic study characterizing their biodegradation behavior and comparing it with the degradation pattern of native starch films has still been published. In the current contribution we characterized the enzymatic degradation pattern of three derivatized starch films by use of a commercial α-amylase from Bacillus licheniformis. Optimum degradation conditions were chosen upon assaying the effect of enzyme load and temperature on the reaction course of native starch films. Under the conditions selected, comparison of different derivatization procedures revealed that the starch film modified with octanoyl chloride was enzymatically hydrolyzed at a much higher rate than native starch film. Maleated starch films also showed higher susceptibility to α-amylolytic hydrolysis than native starch, whereas acetylated starch showed a hydrolysis pattern similar to that of native starch. Differences in degradation rates of chemically modified films were explained in terms of their amylose content which promotes dense networks that hinder the access of starch-degrading enzymes.