Temperature-induced structural variations of retrograded starch gel during long-term storage were investigated in a real food system (wet starch noodles). Fresh starch noodles presented a B-type XRD pattern containing 8.82% crystallinity and 16.04% double helices. In the first 2 weeks, double helices of starch chain formed long-range ordered structure leading to increased crystallinity, and such structural transformation was positively correlated with increasing storage temperature (from 4 °C to 35 °C) and storage time. However, with the extension of storage time to 12 weeks, the disorganization of supra-molecular structure was likely to be observed by decreased crystallinity, double helix and water mobility. Besides, we propose that the area and intensity of Raman band at 2910 cm-1 can be a good indicator for evaluating perfection of crystallinity in starch noodles. These results contributed to a better understanding of mechanisms underlying molecular order changes of retrograded starch gel product during long-term storage.
Keywords: ATR-FTIR; Ordered structure; Retrograded starch; Starch noodles; XRD.
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