本实验分别以天然马铃薯淀粉(potato starch,PS)、改性马铃薯淀粉(包括羟丙基二淀粉磷酸酯(hydroxypropyl distarch phosphate,HDP)、醋酸淀粉(acetate starch,AS)和氧化淀粉(oxidized starch,OS))为基材,通过流延法制备可食用淀粉膜,考察冻融处理对膜物理性质、机械性能、阻隔性能、微观结构和热稳定性的影响.X射线衍射结果表明,马铃薯来源的淀粉颗粒具有典型的B型晶体结构,在成膜过程中淀粉结晶度降低,冻融处理后淀粉膜晶体峰强度明显减弱.扫描电子显微镜观察结果显示,冻融处理破坏了淀粉膜的微观结构,其中PS膜上出现明显裂纹,AS膜上出现蜂窝和层状结构,而HDP和OS淀粉膜具有更完整的形态.热重分析结果表明,随着温度的升高,淀粉膜的热重曲线出现4个质量损失阶段,分别对应水分散失、甘油挥发、淀粉解聚及淀粉分解,而冻融处理对膜热稳定性影响较小.常温条件下,PS膜具有最佳的机械性能,其拉伸强度为2.29 MPa,断裂伸长率为68.82％.在3个冻融循环后,淀粉膜的拉伸强度至少增加了2倍,断裂伸长率普遍降低,而溶解度和水蒸气透过率仅有轻微变化.综合考虑不同淀粉膜微观结构、机械性能、水蒸气透过率及水溶性,HDP膜表现出更好的冻融稳定性,可应用于冷冻低水分食品的保藏.“,”A series of edible films were obtained using native potato starch (PS) or modified potato starches,including hydroxypropyl distarch phosphate (HDP),acetate starch (AS) and oxidized starch (OS) by the casting method.The effects of freeze-thaw (F-T) treatment on the physical,mechanical and barrier properties,microstructure and thermal stability of the films were studied.X-ray diffraction (XRD) indicated that potato starch granules displayed a typical B-type crystalline structure,the crystallinity was damaged during the film-forming process,and the peak intensity was decreased obviously after F-T treatment.F-T treatment damaged the microstructure of starch-based films as observed by scanning electron microscopy (SEM),and there appeared obvious cracks on PS film,and honeycomb-like and lamellar structures on AS film,while OS and HDP films maintained a more complete morphology.In the thermogravimetric curves of starch-based films,four stages of mass loss appeared as temperature increased,corresponding to water loss,volatilization of glycerol,and depolymerization and decomposition of starch,respectively.Nevertheless,F-T treatment had little effects on the thermostability.At room temperature,PS film had the best mechanical property with tensile strength (TS) of 2.29 MPa and elongation at break (EB) of 68.82％.After three F-T cycles,film TS increased at least twice and EB generally declined,while solubility and WVP changed only a little.HDP film displayed much better F-T stability considering the microstructure,mechanical property,water vapor permeability and water solubility collectively,indicating its potential applications in frozen low-moisture foods.