THE INADEQUACY OF UNMODIFIED POTATO STARCH AS DIETARY CARBOHYDRATE FOR THE ALBINO RAT

Abstract

Unmodified (raw) potato starch was poorly utilized, whereas unmodified corn starch and wheat starch were almost completely digested by the rat. The ingestion of unmodified potato starch caused a distention of the caecum and intestines. This enlargement resulted from the accumulation of food residue in the caecum and the consequent formation of gas from fermentation. The utilization of unmodified potato starch was not appreciably improved by the inclusion of either lactose or sucrose in the ration. However, the utilization of potato starch by the rat was improved when the starch was heated in an autoclave at 120° C, in a dry oven at 145° C, or was finely ground. During digestion studies performed in vitro with pancreatin pronounced hydrolysis of both corn starch and wheat starch occurred, but hydrolysis of unmodified potato starch was very slight. Ground potato starch was hydrolyzed very rapidly. The low digestibility of unmodified potato starch was attributed to the resistance of the outermost layer or layers of the granules to attack by alpha-amylase.