猕猴桃片冻干—真空微波联合干燥过程中品质变化及收缩模型

以猕猴桃为原材料,利用冻干—真空微波联合干燥的方式,选取不同的微波功率(0.25,0.30,0.39 W/g),结合猕猴桃在干燥过程中的收缩比、感官品质、色差、复水比、孔隙率等,分析猕猴桃片在干燥过程中的干燥特性、孔隙结构和收缩特性,建立猕猴桃片冻干—真空微波干燥过程中的收缩模型。研究结果表明,不同微波功率下,猕猴桃片的干燥特性有很大差异,微波功率越大,猕猴桃片的感官评分越高,色差越小,复水比越大,收缩比也越大,即达到干燥终点的体积越大,且猕猴桃片的孔隙率也越大。随着干燥的进行,猕猴桃片的水分含量越低,收缩比越小。猕猴桃片的最佳收缩模型为SR=k1+k2 MR+k3(MR)2,R^2>0.99,RSS<0.001,能很好地反映猕猴桃片在冻干—真空微波联合干燥过程中体积收缩的变化。

Quality change and shrinkage model of kiwi during freeze drying and vacuum microwave combined drying

Kiwifruits were respectively dried by freeze-drying and vacuum-microwave combined drying,with different microwave power(0.25,0.30 and 0.39 W/g).In combination with the shrinkage ratio,sensory quality,color difference,rehydration ratio and porosity of kiwifruit in the drying process,the drying characteristics,pore structure and shrinkage characteristics of kiwifruit pieces in the drying process were analyzed,and the shrinkage model of kiwifruit pieces in the process of FD pretreatment vacuum microwave drying was established.The results showed that the drying characteristics of kiwifruit slices changed with the different power of microwave,and the higher the microwave power could cause higher sensory score of kiwifruit slices,less color difference,larger the rehydration ratio,and larger the shrinkage ratio.It was found that the larger volume could made the greater porosity of kiwifruit slices.However,during the drying process progresses,the lower moisture content of kiwi slices resulted in smaller shrinkage ratio.The optimal shrinkage model of kiwi slices was SR=k1+k2 MR+k3(MR)2,R^2>0.99,RSS<0.001,which could well reflect the changes of volume shrinkage of kiwi slices in the process of freeze-drying and vacuum-microwave combined drying.