353 A polymer science approach to starch retrogradation.

I. A. FARHAT, J. M. V. Blanshard, and J. R. Mitchell. Division of Food Sciences, School of Biological Science, University of Nottingham, Loughborough LE12 5RD, UK.

The retrogradation of rubbery extruded waxy maize starch was studied using wide angle x-ray diffraction and proton NMR relaxometry as a function of composition and storage temperature. The Lauritzen-Hoffman theory of crystallization of chain folded synthetic polymers combined to the Ten-Brinke et al. equation describing the plasticization of the amorphous amylopectin by water and the Flory equation relating the melting temperature of the starch crystallites to the water content was applied. This approach enabled the successful modelling of the results in both temperature and water content domains over a wide range of composition and storage conditions. The effect of various sugars on the kinetics of starch retrogradation was also examined in the same context.