WATER MOBILITY IN STARCH SUCROSE SYSTEMS - AN O-17 NMR-STUDY

Sucrose/starch mixtures containing 0, 10, and 20% sucrose were equilibrated with water vapor enriched to 1%17O, at water activities (aw) of 0.88, 0.93, and 0.97. In all samples, a significant quantity of water did not appear in the NMR spectrum, presumably because it was immobilized. The amount of water, which was somewhat mobile and appeared in the spectrum, increased with increasing aw and sucrose content. The relaxation time of this NMR active water was strongly dependent on sucrose content, in a way that could not be explained by any simple model. Thus, the presence of sucrose has a profound effect on interaction of starch with water. Copyright © 1990, Wiley Blackwell. All rights reserved