香蕉的真空冷冻干燥技术

以成熟度"果蒂黄中带绿色，果皮淡黄色"的香蕉为材料，测得香蕉真空冷冻干燥过程的共晶点温度和共熔点温度分别为-33.5℃和-22.0℃，由此确定冻结温度为-43~38℃;分析了香蕉干燥过程的冻干曲线变化趋势;对香蕉真空冻干技术工艺的原料成熟度、预处理方法及流程中的过程参数进行研究。结果表明∶香蕉处于"果蒂黄中带绿色，果皮淡黄色"成熟度时，冻干品的质量及风味效果最佳，采用"0.05%柠檬酸+0.5%氯化纳+0.6%氯化钙"护色剂浸渍10min具有良好护色保脆的效果。香蕉较优化的真空冷冻干燥技术工艺参数∶香蕉片厚度取5~7mm，以速冻方法冻结，加热板温度设定45℃，干燥室真空度控制于20~30Pa范围等。

Studies on Vacuum Freeze-drying Technologies for Mature Banana Fruits

The temperatures of eutecic point and co-melig point for mature banana fuits withyellow-greenish pedicels and liht-yelowish skins were determined in a vacuum freze-drying process, and they were-33.5 C and-22.0°C separately, based on which the frezing temperatures determined to range from-43 C to-38C. The changes of the freeze-drying curve of the bananas were analyzed. Banana maturity and methods of pre-treatment as well as the parameters during vacum freze-drying of the bananas were also studied. The results suggested the frozen products were the best in aste and appearance when the banana fuits used as material were in the above-mentioned maturity.The mature banana fruits were soaked for 10 min with a color-keeping agent (0.05% citric acid＋0.5% sodium chloride＋0.6% calcium chloride),sliced 5~7mm thick,quickly frozen and then vacuum dried by maintaining the heating plate temperature at 45 C and the drying chamber vacum at 20~30 Pa.The technological parameters observed from these products were found optimum.