Prediction and Validation of Water Condensation on Cold-stored Apples under Various Hygrothermal Conditions in a Packinghouse

Fruit condensation after cold storage diminishes operational efficiency and increases the risk of microbial contamination during packinghouse and distribution operations.Water condensation on cold-stored apples was predicted using psychrometric methods and validated through laboratory investigations to offer effective fruit temperature control guidelines.A survey conducted in 2023 at eight agricultural product processing centers (APCs) revealed that the storage temperatures and relative humidity (RH) levels for apples ranged from 0.0 to 1.0C and exceeded 85%, respectively.Packinghouses were managed under ambient conditions or air-conditioned environments, targeting atmospheres of 20C with 60% RH.A theoretical estimation of the vapor pressure deficit (VPD) between the fruit and packinghouse environments indicated that raising the fruit temperature to prevent water condensation could be realized at temperatures ranging from 0.5C to 17C, depending on the atmospheric conditions.The fruit temperature for vapor pressure equilibrium (VPE) was 12.5C under the targeted environmental condition of 20C with 60% RH.Six treatments, combining the fruit temperatures with atmospheric simulations inside a packinghouse, were applied as a validation experiment.The simulated atmospheric temperature and humidity conditions were 10C and 20C with 50% RH and 80% RH, respectively, for 0C fruit temperature, and 20C with 60% RH and 80% RH at 12C.The laboratory experiment demonstrated that water condensation varied among the treatments, consistent with the theoretical VPD estimations.A significant regression model was developed between the VPD and the amount of condensation on the apples.The results of this study suggest the feasibility of psychrometrics for detailed and effective temperature management strategies for cold-stored apples during packinghouse operations.