The pre-cooling of fruits and vegetables is an important step in the cold-chain
and a proper pre-cooling time period can assure the quality of fruits and vegetables. Here the lumped parameter method was set up to estimate the required time period after which the center temperature of the grape reaches the air temperature in the cooling store by analyzing the heat transfer of the grape in pre-cooling
and was confirmed by the experiment. The results show that adopting the qualitative size R
the method can estimate the pre-cooling time period of the grape properly when the air velocity in the cooling store is larger than 1.1m/s.