Differential Scanning Calorimetry of Retrogradation and Freezing Process in Starch

1. 淀粉与糖的热性质：用差示扫描量热法（DSC）研究了10-50%淀粉与0-200%糖降解后的糊化和再糊化。淀粉与糖还原后的再糊化热光谱与天然淀粉颗粒与糖的糊化热光谱有很大的不同。天然颗粒的表面状态可以保护淀粉不受糖溶液中水分子的渗透，糊化温度随着糖浓度的增加而升高。转变起始温度Ts、峰值Tp、结论Tc随糖水比x呈线性增加。在20%淀粉的情况下，表示为Ts (Tp和Tc) =22x + 52(60和71)C。2. 淀粉冻结：糊化淀粉冻结后不久，在游离水峰-5℃的下侧出现另一个吸热峰。即使在-18℃的低温下，在几天的时间里，它也增长到自由水熔化能的10%左右。DSC是一种灵敏的检测水在冻结温度下迁移率的方法。

1. Thermal properties of starch with sugar: Gelatinization and re-gelatinization after retrogradation of 10-50% starch with 0-200% sugar were studied by differential scanning calorimetry (DSC). Thermal spectra of re-gelatinization after retrogradation of starch with sugar were far different from those of gelatinization of the natural starch granule with sugar. The surface state of the natural granule may protect the starch from penetration of water molecules in the suger solutionThe gelatinization temperature shifted to higher temperature as increase of the sugar concentration. Start temperature of the transition Ts, peak Tp, conclusion Tc were linearly increased with x, the fraction of sugar to water. It was expressed as Ts (Tp and Tc) =22x + 52 (60 and 71) C in the case of 20% starch. 2. Freezing of starch: Another endothermic peak appeared at -5 C lower side of the free water peak soon after freezing of gelatinization starch. It grew to about 10% of the melting energy of the free water during several days even at -18 C. DSC gives a sensitive method to detect the mobility of water at freezing temperature.