预处理对红枣分段间歇微波耦合热风干燥特性及品质的影响  

Effects of pretreatment on characteristics and qualities of Chinese jujube drying by segmented intermittent microwave coupled with hot air

作　　者：罗东升[1,2,3] 朱玉丽[1,2,3] 王梅 胡小松[1,2,3] 吴继红[1,2,3] 

机构地区：[1]中国农业大学食品科学与营养工程学院,北京100083 [2]国家果蔬加工工程技术研究中心,北京100083 [3]农业部果蔬加工重点开放实验室,北京100083 [4]哈密职业技术学院,哈密100875

出　　处：《农业工程学报》2017年第7期261-267,共7页Transactions of the Chinese Society of Agricultural Engineering

基　　金：国家科技支撑计划课题(2012BAD36B07)

摘　　要：为探究分段间歇微波耦合热风干燥红枣最佳工艺,分析不同预处理对红枣品质的影响。该文采用响应面法,优化出最佳干燥工艺为:第一段间歇比为4、水分转换点为1g/g、第二段间歇比为6。此条件下,干燥时间为625.27 min,能耗为5 128 kJ,维生素C质量分数为419 mg/(100g),经验证,模型预测误差小于5%。基于最佳工艺,探究热烫、油酸乙酯结合预冻和高压二氧化碳3种预处理方式对红枣干燥速率、单位耗能及品质的影响。结果显示,油酸乙酯结合预冻处理组干燥时间最短(P<0.05)、能耗最低(P<0.05);高压二氧化碳处理组干燥后维生素C、总酮、总酚质量分数,抗氧化能力均最高(P<0.05);热烫预处理组褐变程度最低(P<0.05),组间色泽无明显差异(P>0.05)。试验证实,高压二氧化碳联合分段间歇微波耦合热风干燥是一种高效干燥技术,能保证红枣的营养品质,研究为该项技术的推广提供基础数据。This research was aimed to explore the optimal drying process of Chinese jujube by segmented intermittent microwave coupled with hot air drying（IMAD） and to study the influence of different drying pretreatment technologies on drying rate, unit energy consumption and quality of jujube. The drying pretreatment technologies included dipping in alkaline emulsion ethyl oleate solution followed by slow freezing at-18 ℃（AEEO ＋ freeing）, high pressure carbon dioxide（HPCD）, and hot water blanching（HWB）. Firstly, to obtain the best drying process, intermittent ratio in the first drying stage（IR1）, transition point in moisture content between the 2 stages of drying（TPMC）, and intermittent ratio in the second drying stage（IR^2） were set as the independent variables, and the drying time, unit energy consumption and vitamin C content after drying were set as the dependent variables. According to central composite design of the response surface technology, the obtained optimal process parameters were IR1 of 4（the ratio of runtime to stand-by time of microwave oven was 5 s ： 15 s）, TPMC of 1, and IR^2 of 6（5 s ： 25 s）. On this condition, the drying time was the shortest（625.27 min）, the unit energy consumption was the minimum（5 128 kJ） and the vitamin C content after drying was the maximum（419 mg/（100 g））. Then, to know the effect of drying pretreatment technologies on quality, Chinese jujube samples were dried respectively by 3 pretreatment technologies combined with the best drying process. The results implied that the special epidermis structure of Chinese jujube may be damaged during drying pretreatments, and especially the method of AEEO ＋ freeing led to the moisture in Chinese jujube much more easily diffused and evaporated. So the drying rate was obviously improved and the energy consumption was reduced. Correspondingly, with regard to drying rate, the AEEO ＋ freeing groups were the maximum, followed by the HPCD groups and the HWB groups, and the control grou

关 键 词：干燥 优化 品质控制 红枣 预处理 分段间歇微波耦合热风干燥 

分 类 号：TS255.36[轻工技术与工程—农产品加工及贮藏工程]