皱皮木瓜真空冻干工艺优化及基于LF-NMR技术的复水特性研究  

Optimization of Vacuum Freeze-drying Process and Rehydration of Chaenomeles speciosa(Sweet.) Nakai Based on Low-field NMR Technology

作　　者：崔莉[1] 杜利平[1,2] 闫慧娇 刘伟[1] 耿岩玲[1] 王晓[1] 

机构地区：[1]山东省中药质量控制技术重点实验室山东省分析测试中心,济南250014 [2]食品科学与工程学院山东农业大学,山东泰安271018

出　　处：《中国食品学报》2019年第6期124-133,共10页Journal of Chinese Institute Of Food Science and Technology

基　　金：国家自然科学基金面上项目(81473298);山东省科技发展计划项目(2014GSF119031)

摘　　要：目的:对皱皮木瓜片的真空冷冻条件进行优化,研究木瓜片复水过程中水分状态变化。方法:采用单因素试验结合Box-Behnken响应面法,分别以复水比和色差值为指标,考察木瓜片厚度,真空冷冻干燥机的隔板温度以及真空度3个因素对冻干工艺的影响,优化皱皮木瓜片冻干工艺;利用低场核磁共振技术比较真空冷冻干燥和热风干燥的木瓜片成品复水过程中水分状态的变化情况。结果:确定皱皮木瓜真空冷冻干燥的复水比最佳工艺条件:木瓜片厚度4mm,隔板温度40℃,真空度2.4mbar;色差值最优的组合为:木瓜片厚度7.45mm,隔板温度28.37℃,真空度2.02mbar。NMR试验表明,复水过程中进入木瓜片中的水很快转化为不易流动水,结合水和自由水变化不大,且真空冷冻干燥的木瓜片中不易流动水增加较快,说明冻干比热风干燥的木瓜片品质好。结论:本研究结果为优化的皱皮木瓜真空冷冻干燥工艺参数,低场核磁共振技术可用于表征皱皮木瓜复水过程中水分状态的变化。Object: The changes in moisture state of Chaenomeles speciosa(Sweet.) Nakai during rehydration process were investigated and the optimization of vacuum freeze drying conditions were couducted. Methods: the dependence of the rehydration and color difference regarding as indexes on three factors(papaya slice thickness, clapboard temperature and vacuum degree) were studied via combination of the single factor experiment with Box-Behnken response surface method to optimize freeze-drying process. Comparable study on the changes in moisture state of papaya slices subjected to either vacuum freeze drying or hot-air drying during rehydration process were conducted by Low Field-Nuclear Magnetic Resonance (LF-NMR). Results: Taking the rehydration as evaluating indexes, the optimized processing conditions on papaya slices by vacuum freeze drying was: slice thickness 4 mm, clapboard temperature 40 ℃ and vacuum degree 2.4 mbar. Taking the color difference as evaluating indexes, the optimized processing conditions was: slice thickness 7.45 mm, clapboard temperature 28.37 ℃ and vacuum degree 2.02 mbar. The LF-NMR measurements showed the moisture state of Chaenomeles speciosa(Sweet.). The slices treated with vacuum freeze drying translated into immobilized water more quickly than that subjected to hot-air drying, whereas bound water and free water rarely changed similarly during rehydration process, indicating the quality of vacuum freeze drying can be preserved well relative to hot-air drying treatment. Conclusions: the results obtained from this study can provide theoretical references to practical vacuum freeze drying of Chaenomeles speciosa(Sweet.) Nakai slices. Meanwhile, LF-NMR method was effective to assess water distribution during food rewater process of papaya slices.

关 键 词：皱皮木瓜 真空冷冻干燥 LF-NMR(低场核磁共振) 复水特性 

分 类 号：TS255.3[轻工技术与工程—农产品加工及贮藏工程]