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Gelatinization and retrogradation properties of acetylated corn starch studied by DSC

Native starch has limitations in food industry applications such as high tendency toward retrogradation, low thermal resistance and shear resistance. Therefore starch is often modified in different ways to change and improve its performance. The aim of this research was to study effect of acetylation on gelatinization and retrogradation properties of corn starch. Acetylation was carried out by treating corn starch with 4, 6 and 8 % (w/w) of acetic anhydride at room temperature (the percentages of acetyl group were 1.257, 1.739 and 2.212 %). Differential scanning calorimetry (DSC) was used to investigate gelatinization and retrogradation properties of acetylated corn starch. Studies were conducted on model solutions with starch concentration of 30 %. Starch suspensions were heated in a temperature range from 25 °C to 95 °C at heating rate of 10 °C/min. After gelatinization, samples were cooled and stored at 4 and 25 °C. The enthalpy of retrogradation was measured by DSC after seven and fourteen days of storage. It was observed that acetylated corn starches gelatinized at lower temperatures and had lower values of gelatinization enthalpy in comparison with native starch. Comparing to acetylated starches, native corn starch had significantly higher tendency of retrogradation after 7 and 14 days of storage at 4 and 25 °C.

Corn starch; acetylation; gelatinization; retrogradation; DSC

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