An Discussion of Vegetables Freezing Rates of Vacuum Cooling and Refrigerator Cooling

Vegetables are perishable agricultural products. In order to prolong the fresh-keeping period of agricultural products, vegetables should be cooled rapidly soon after harvest. The pre-cooling of vegetables after harvest is the first link of cold chain; therefore, it's especially important. The boiling point of water descends with the reduction of pressure inside the container. The vacuum cooling utilizes the water content evaporation on the surface of vegetables to take away a great quantity of vaporization heat, and lower the temperature of vegetables swiftly. The experiment took the ways of vacuum cooling and refrigerator cooling respectively to test the freezing rates of head vegetables, leaf vegetables, and root vegetables. The experiment findings show that vacuum cooling has best freezing effect on leaf vegetables, and second best freezing effect on head vegetables.