Vapor pressure deficit and water loss patterns during simulated air shipment and storage of beit alpha cucumber.
Laurin E., Nunes M.C.N., Emond J.P., Brecht J.K.
5th International Postharvest Symposium . Volume of Abstract . Verona, Italy 6-11 June 2004. page 17
2004
บทคัดย่อ
Harvested commodities lose moisture by transpiration, with the rate affected by a environmental factors such as temperature (T), relative humidity (RH), and atmospheric pressure (P).Commodities are commonly exposed to high T, low P, and large vapor pressure deficit (VDP) during air shipment, which can increase their transpiration rate and result in undesirable loss of moisture.The objective of this work was to understand the VPD and water loss patterns of Beit Alpha cucumbers under combined flight conditions (T, RH, P) in airtight and open containers.To simulate flight conditions, cucumbers were stored for 6 hours at 0.7 atm, 20 °C, and initial RH of 70% in airtight or open containers with an air-flow rate of 0.415 Ls-1, and with 1.0 atm cold rooms at 20 °C and 70% RH or 7 °C and 90% RH for 7 days.The VDP was monitored during flight simulation and weight loss was evaluated after harvest, after flight simulation, and daily for 7 days.Exposure of cucumbers to 0.7 atm in either airtight or open containers increased moisture loss compared with 1 atm.The VPD was higher in open containers, enhancing transpiration, and leading to greater moisture loss during the simulated air shipment as well as throughout the storage period.The atmosphere in airtight conditions was quickly water –saturated, limiting transpiration rate and moisture loss during the air shipment simulation.Loss of moisture from the cucumbers exposed to 0.7 atm in airtight containers was significantly greater throughout the storage period compared with fruit in 1.0 atm airtight containers.These latter results suggest that low p during air transport may induce physiological stresses on cucumbers, especially in the water diffusion pathway though the epidermis.