The retrogradation of waxy maize starch extrudates: Effects of storage temperature and water content

✍ Scribed by I. A. Farhat; J. M. V. Blanshard; J. R. Mitchell

• Publisher: Wiley (John Wiley & Sons)
• Year: 2000
• Tongue: English
• Weight: 213 KB
• Volume: 53
• Category: Article
• ISSN: 0006-3525
• DOI: 10.1002/(sici)1097-0282(20000415)53:5<411::aid-bip5>3.0.co;2-m

✦ Synopsis

The effects of water content and storage temperature on the kinetics of the retrogradation of nonexpanded waxy maize starch extrudates were studied using 1 H pulsed NMR and wide-angle X-ray diffraction. The increase in crystallinity observed by XRD was accompanied by a decrease in the relaxation times of the solid-like component of the NMR free induction and the spin-echo decays, and an increase in the contribution of the solid-like component to the total signal. The dependence of the rate of starch retrogradation on the storage temperature showed the typical "bell-shaped" behavior, which was successfully modeled using the Lauritzen-Hoffman theory of crystallization of chain-folded polymers. This theory was extended to model the effect of water content on the rate of isothermal crystallization by exploiting the ten-Brinke and Karasz, and the Flory equations to describe the dependence of the glass-transition and the melting temperatures on water content.