Preparing modified starch by using dry method of microwave has been gradually promoted in China. It has some advantages such as short process, low energy consumption, easy to operate. The process of preparing oxidation starches by two oxidants; chlorine dioxide (to oxidation starch A) and sodium chlorate (to oxidation starch B) was investigated, and the characteristics of the modified starches were also discussed in this paper. The results on theprocess study showed that the oxidation reaction on starch could be caused by both oxidants using dry method of microwave heating. The carboxyl group content of oxidation starch A and oxidation starch B prepared by the method were (0.068 ±0.002)% and (0.586 ±0.002)% separately. The results on the properties of the modified starches showed that the thermal viscosity stability of the oxidation starch was improved and freeze - thaw stability of oxidation starch B was better. The release water rate of oxidation starch B was only 23.7% after freeze thawing twice. The alkali resistance of oxidation starch A was good, but not to the acid resistance. However, oxidation starch B showed a better alkali resistance and acid resistance. The oxidizing reaction to the modified starches happened in amorphous of the starch through X - ray diffraction. However, the crystal structure remains the same as the original starch.%干法制备变性淀粉已逐步在国内推广,它具有流程短,能耗低,操作简便等优点.采用微波干法工艺,研究了二氧化氯、氯酸钠两种氧化剂制备氧化淀粉(分别为氧化淀粉A和氧化淀粉B)的工艺和变性淀粉的性能.工艺研究表明,两种氧化剂均能通过微波干法制备氧化淀粉,而氧化淀粉A和氧化淀粉B的羧基含量分别为(0.068±0.002)％和(0.586±0.002)％.性能研究表明,氧化淀粉的热黏度稳定性得到了改善,氧化淀粉B的冻融稳定性较好,经2次冻融,析水率仅为23.7％；氧化淀粉A耐碱性能好,耐酸性较差,氧化淀粉B则具有较好的耐酸耐碱性；X-射线衍射结果表明淀粉的氧化反应主要发生在淀粉的无定型区,而晶体结构仍与原淀粉相同.
展开▼
