Resistant starch in the diet has been proven to provide health benefits, including interventions of diabetes, obesity, and colon cancer. Type 2 resistant starch is found in high-amylose maize starch, and the resistant starch content of individual line of high-amylose maize starch correlates with the amylose content of the starch (r = 0.94). After a thermal-stable α-amylase hydrolysis of the high-amylose maize starches at 95-100 °C (AOAC method 991.43), the resistant starch residues display similar onset (100.7 - 107.7 °C), peak (118.6 - 121.4 °C) and conclusion (139.7 - 158.8 °C) gelatinization temperatures. During the development of starch in the endosperm of GEMS-0067 high-amylose maize line, the resistant starch content of the starch increased with the maturation of the kernel. The gelatinization thermograms of the starches harvested on 15, 20, 30, 40, and 54 days after pollination (DAP) showed a thermal transition peak with the peak temperature at 76.6 - 81.0 °C. A second peak at ca. 97.1°C first appeared on 20 DAP and gradually developed to a major peak on 40 and 54 DAP. After subjecting the starch to solvent extraction of lipids using 85% methanol, the second peak disappeared, indicating the peak resulting from disassociation of amylose-lipid complex, but the conclusion gelatinization temperature remained the same. The percentage of the enthalpy change at temperatures above 95 °C correlated well with the resistant starch content of the starch determined using chemical method (r = 0.92). The results showed that DSC could be used to determine the resistant starch content of starch.
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