二氧化氯的催化法制备及其对冬枣的保鲜效果

Preparation of Chlorine Dioxide by Catalytic Method and Its Preservation Effect on Winter Jujube

[目的]为冬枣保鲜提供科学依据。[方法]研究了以氯酸钠和硫酸为原料,尿素为还原剂,MnO2/Cr2O3为催化剂制备二氧化氯的方法。并用该方法制备了低温型缓释二氧化氯制剂1、2号,比较了其对低温贮藏冬枣的保鲜效果。[结果]经正交试验优化后,制备二氧化氯的最佳工艺为:温度70℃,酸度6mol/L,m(MnO2)∶m(Cr2O3)=3∶1,n(NaClO3):n(CO(NH2)2)=2.5∶1,此条件下,二氧化氯产率达95%,纯度达95%以上。放置缓释二氧化氯制剂后,冬枣的可滴定酸和Vc含量均高于对照组,失重率、呼吸强度和乙醇含量均低于对照组。二氧化氯释放量大的1号缓释剂的保鲜效果好于释放量小的2号缓释剂。[结论]缓释二氧化氯制剂可有效提高冬枣的保鲜效果。

[Objective]The purpose of the research was to supply scientific basis for preservation of winter jujube. [Method]The preparation method of chlorine dioxide with sodium chlorate and sulfuric acid as raw materials,urea as reducer and MnO2/Cr2O3 as catalyst was researched. And the low-temperature and slow-release chlorine dioxide preparations 1 and 2 were prepared by using this method and their preservation effects on winter jujube stored at low temperature were compared. [Result]After optimization by orthogonal test,the best preparation technology of chlorine dioxide was as follows：the temperature was 70 ℃,the acidity was 6 mol/L,the proportions of m（MnO2） to m（Cr2O3） and n（NaClO3） to n（CO（NH2）2） were 3：1 and 2.5：1 resp. Under this condition,the yield rate and purity of produced chlorine dioxide all reached above 95%. After the slow-release chlorine dioxide preparation was applied,compared with control group,the contents of titratable acid and Vc in winter jujube were higher and its weight loss rate,respiratory intensity and alcohol content were lower. The preservation effect of slow-release preparation 1 with larger release amount of chlorine dioxide was better than that of slow-release preparation 2 with smaller release amount. [Conclusion]The preservation effect of winter jujube could be enhanced by using slow-release chlorine dioxide preparations effectively.