脉冲电场预处理对苹果冷冻干燥崩塌温度及干燥品质的影响

项目名称： 脉冲电场预处理对苹果冷冻干燥崩塌温度及干燥品质的影响

项目编号： No.31501212

项目类型： 青年科学基金项目

立项/批准年度： 2016

项目学科： 农业科学

项目作者： 吴亚丽

作者单位： 太原理工大学

项目金额： 20万元

中文摘要： 果蔬冷冻干燥达到崩塌温度时，存在组织断裂、细胞塌缩等现象，影响干燥品质。脉冲电场作为非热加工预处理技术，与冷冻干燥结合，能加快水分扩散传质过程，提高果蔬干燥层温度，改善品质。本研究选取典型果蔬苹果为研究对象，以改善细胞崩塌，提高干燥速率与品质为目的，开展不同脉冲电场参数预处理后苹果的冷冻干燥试验，通过低温冻干显微镜等技术手段探索经脉冲电场预处理后苹果微观结构与干燥层温度之间的关系，确定预处理前后崩塌温度的范围；基于分形几何理论，结合苹果的结构与物性参数，建立预处理后苹果冻干过程的传热传质模型，分析冻干过程中崩塌温度和样品含水率的变化规律，揭示脉冲电场预处理对苹果冷冻干燥崩塌温度的影响机理；通过研究脉冲电场和冻干过程参数对苹果干燥品质的影响，获得优化的脉冲电场和冻干过程参数组合，达到提高干燥速率，改善干燥品质的目的。

中文关键词： 脉冲电场；冷冻干燥；苹果；崩塌温度；干燥品质

英文摘要： During the freeze drying process, when the drying temperature was reached the collapse temperature, the scasoning check and collapse phenomena were appeared and thus reduce the drying effect. Pulsed electric field as non-thermal processing for drying on fruits and vegetables in the freeze drying not only can increase the diffusion coefficient of water and the drying layer temperature, but also can improve product quality and reduced energy consumption. To prevent the collapse of tissue, improve the drying rate and quality, the drying experiments were conducted with the typical fruits and vegetable, such as apple, which were pretreated by pulsed electric field. The scanning electron microscope observations were performed combined with low temperature drying microscopy techniques to analysis the effect of pulsed electric field pretreatment on drying temperature and micro-structural of apple tissues, and determined the collapse temperature. Moreover, the simultaneous heat and mass transfer model was established to predict the drying temperature and moisture distribution in apple tissues that pretreated by pulsed electric field, during freeze drying using fractal geometry theory. And the mechanics mechanism of pulsed electric field on collapse temperature of apples was revealed. According to study the effect of the parameters of pulsed electric field and drying processing on the quality of apple, the optimal parameters of pulsed electric field and vacuum freeze drying processing technology were obtained. The results can reduce energy consumption and improve product quality, thus it provide a strong theoretical support for thermal control of agricultural products drying.

英文关键词： Pulsed electric field;Freeze drying;Apple;Collapse temperature;Drying quality