Differential Scanning Calorimetry of Retrogradation and Freezing Process in Starch

1.用差示扫描量热法(DSC)研究了含糖淀粉的热性质：用差示扫描量热法(DSC)研究了10-50%淀粉与0-200%蔗糖回生后的糊化和复糊化。淀粉加糖回生后再糊化的热谱与天然淀粉颗粒加糖后再糊化的热谱有很大不同。天然颗粒的表面状态可能会保护淀粉免受水分子在糖溶液中的渗透，糊化温度随着糖浓度的增加而向更高温度移动。开始转变温度T_s、峰T_p、T_c与糖水比x呈线性关系。当淀粉含量为20%时，T_s(T_p和T_c)=22x+52(60和71)C。2.淀粉冻结：糊化淀粉冻结后，在自由水峰下侧-5℃处出现另一个吸热峰。即使在-18℃下，它也在几天内增长到自由水熔化能的10%左右。DSC提供了一种灵敏的方法来检测水在冰点温度下的流动性。

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.