苹果冷冻干燥过程的优化及最佳工艺条件的确定

Establishment for the Optimum Technological Conditions and the Optimized Process for Apple Freeze-Drying

对苹果进行了冷冻干燥实验,确定了苹果片冻干工艺条件,计算了冻结时间,建立了苹果片冻干的传热传质模型,由模型计算出不同厚度物料的理论干燥时间,并与实验值进行了比较.探讨了冻结速率、物料温度、干燥室及捕水器温度、压强对冷冻干燥过程及制品质量的影响.苹果冷冻干燥的适宜工艺参数为冻结温度-35 ℃,冻结时间1 h,升华干燥时干燥仓压强70～90 Pa,解吸干燥时干燥仓压强20～30 Pa,解吸干燥时物料温度50～60 ℃.

xThe freeze-drying experiment of apple and obtained the freeze-drying technology for apple slice were investigated in the paper, and the freezing time was calculated and the model of heat-transfer and mass-transfer for apple slice was established, and the theoretic drying times with different thickness of apple slice were calculated by the model, and the comparison between calculation and experiment value was discussed. The influence of freezing rate, materiel temperature, the temperature for drying room and water catching machine on the freeze drying process and the quality of the products were discussed. The parameters for freeze-drying technology of apple slice are that the freeze time is 1 h, terminal freezing temperature,-35 ℃, the pressure for sublimation and drying is 70-90 Pa, and 20-30 Pa for desorption and drying, the materiel temperature in desorption is 50-60 ℃.