高温果汁真空冷却特性

为减小真空冷却中液体飞溅并研究不同条件对降温速率的影响，采用控制变量法，通过改变容器的形状、顶部材料与孔径大小、物料的相对装载量、不同初始温度和冷却终温等条件，测定果汁降温过程的质量和温度变化，根据测试结果计算出不同变量下的无效失水率和降温速率。研究表明，降温速率大且无效失水量小的最佳工艺条件为使用相对装载量23.3%、容器顶盖材料为刚性材料、孔径5 mm的长方形容器，由初始温度80℃降至冷却终温为25℃，此时的无效失水率最小，降温速率最快。

Characteristic Analysis of Vacuum Cooling of High Temperature Juice

In order to alleviate the liquid spatter during vacuum cooling and explore the influence of different conditions on the cooling rate,the control variable method was used to test the quality and temperature changes of the juice during the cooling process by changing the container shape,top material,aperture size,relative loading capacity of materials,and different initial and final temperatures. The ineffective water loss rate and cooling rate under different variables were calculated based on the test results.The study showed that the optimal condition for achieving a high cooling rate and low ineffective water loss was as follows:a rectangular container with a relative load of 23.3%,rigid container top material,and aperture size of 5 mm,as well as a decrease in temperature from 80 ℃to 25 ℃. At this time,the ineffective water loss rate was the lowest,and the cooling rate was the fastest.