The cold chain in low temperature logistics is closely related to modern life. Temperature control is required when vegetables and fruits are collected, and pre-cooling is the first step of the cold chain, so it is very important. Vacuum pre-cooling decreases the temperature of vegetables and fruits rapidly and uniformly as the water on the vegetable and fruit surfaces evaporates and takes away a large amount of heat. This experiment used vacuum to cool vegetables, kept the vacuum at 5.5~7 Torr, and examined the vegetables with humidification and without humidification before cooling to study their weight loss rate and cooling rate.
