In vitro digestibility of ultrasound-treated corn starch

Abstract

Ultrasound technologies are increasingly used for the production of modified starches. An accurate understanding of the effects of ultrasound treatment on the morphological and functional properties of starch granules and dispersions is still under progress. This work studied the digestibility of corn starch as affected by ultrasound treatment (24 kHz). Results based on SEM, XRD, FTIR and apparent viscosity analysis of native and sonicated starches were conducted to gain insights regarding the mechanisms affecting starch digestibility due to ultrasound treatment. The resistant starch content of native starch dispersions increased from 4.7% to 6.2% after 16 min of sonication. This increase was attributed to morphological and crystallinity changes that reduced the structure of the starch granule channels. For gelatinised starch dispersions sonicated 16 min, the resistant starch content increased from 2.1% to 4.0%, while the rapidly digestible starch fraction showed an increase from 42.9% to 60%, an affect that was attributed to the formation of short-chained amylose molecules by effects of ultrasonic cavitation.