子芋冷冻升华干燥最佳工艺研究

Optimal Technology of Freeze-Drying Process of Son-taroes

研究子芋冷冻升华干燥时的工艺特性 ,包括降温速率、真空度、加热板温度设定程序以及冷凝器温度对冷冻干燥过程和产品质量的影响 ,并利用非线性回归分析法对最佳的加热板温度设定程序所对应的物料温度变化曲线的经验公式进行拟合。得出的子芋冻干最佳工艺条件为 :快速冷冻到 - 30℃ ,降温速率为 - 0 .2℃ / m in;干燥时真空室的真空度为 6 6 .7Pa;冷凝器温度为 - 34℃～ - 40℃ ;加热板温度的设定程序为 :在 1.5 h内升温至 80℃ ,恒温5 h,而后在 1h内降温至 70℃ ,恒温 1h,又在 1h内降温至 6 0℃后自动关闭加热器 ,自然冷却至室温。按此生产的产品感官效果明显好于热风干燥产品 ,且复水速率高 34倍 ,复水量高 1.3倍 ,体积收缩率仅为热风干燥产品的40 .7% ,重要营养成分α- VE的保存率提高 1.15倍。

The technological characteristics of son taroes of Colocasia esculenta Schott during freeze drying process was studied, including the influence of the temperature decreasing rate, the vacuum, the temperature and heating programme of heating plate, and the temperature of condenser to the process and the product quality of freeze drying taroes. The optimal technogical condition was: the temperature of freezing -30℃, the temperature of decreasing rate -0.2℃/min, the vacuum 66.7 Pa, the temperature of condenser -34℃^-40℃, the programme of heating plate was rising the temperature to 80℃ within 1.5 hours, keeping the temperature for 5 hours, then decreasing the temperature to 70℃ within 1 hour, keeping the temperature for 1 hour and then decreasing the temperature to 60℃ within 1 hour, at last, taking off the heater automatically, cooling the product to the room temperature naturally. The sensory quality of freeze drying tatoes was obviously better than that of the products dried by the hot air. The restoration velocity in water was 34 times, the ability for restoration in water was 1.3 times, the contract rate of volume was 40.7% and the keeping rate of main nutrient α VE of freeze drying taroes was 2.15 times of that of the product dried by hot air.