Vacuum Precooling Model of Longan Fruit

A kinetic model on vacuum precooling fruit based on Fick diffusion law was established. The model well predicted experimental results and showed that at low pressure the cooling rate is inversely proportional to the square of the fruit radius and related to the tempertature of condenser. Longan fruit was cooled from 28 ℃ to 7 ℃ within 11 minutes in a vaccum cooling cell. The experimental data showed a good fit with model. And the result showed that the vacuum cooling is a good way for fruit treatment after harvest.