Heat-moisture treatment under mildly acidic conditions alters potato starch physicochemical properties and digestibility

초록

Potato starch was subjected to heat-moisture treatment (HMT; 120 degrees C, 3 h) under mildly acidic conditions (pH 5, 6, or 6.5 [control]) at moisture levels of 15,20 or 25%. HMT starches exhibited significantly delayed pasting times and reduced overall paste viscosities, amylose leaching, and granular swelling characteristics relative to native starch, as well as enhanced levels of thermo-stable resistant starch (approximate to 24%). HMT appeared to alter/enhance short-range chain associations (FT-IR) within amorphous and/or crystalline regions of starch granules. However, the extent of physicochemical change and RS enhancement during HMT was most facilitated by a mildly acidic condition (pH 6) at higher treatment moisture levels (20 or 25%). These conditions promoted limited hydrolysis of amylopectin molecules, primarily at alpha-(1 -> 6) branch points, likely enhancing mobility and interaction of starch chains during HMI. Thus, a slightly acidic pH might reduce conditions and/or timeframe needed to impart physicochemical changes and reduced digestibility to potato starch. (C) 2013 Elsevier Ltd. All rights reserved.

키워드