Thermal Transitions in Gelatinized Wheat Starch at Different Moisture Contents by Dynamic Mechanical Analysis

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Abstract
Gelatinized starch was analyzed by DMA and the resulting overlapped tan 5 curve was characterized. At high moisture contents (>30% w/w), transitions around ice melting region of tan 5 peak (>50°C wide) showed skewness at the low temperature side. After deconvolution, a symmetrical, sharp, main peak was correlated with the ice melting endotherm but the cause of the lower temperature asymmetrical peak was not identified. At <30% moisture, two deconvoluted Gaussian peaks indicated at least two separate, broadly distributed domains (slightly frequency dependent). Transitions (other than ice melting), if caused by glassy rubbery transitions, were small in tan 5 and broad (50–100°C wide).