Cold Treatment Management During a Simulated Refrigerated Transport of Citrus Fruit at Industrial Scale

In the present paper are discussed the results of simulated refrigerated transport of citrus fruit at industrial scale. Fruit temperature distribution in a refrigerated cargo (reefer) has been studied in order to reduce the temperature difference in the load, to increase quality and shelf life after shipment. The mean temperature difference between the probes placed in the head space was shorter than 0.5°C while graphic peaks showed the temperature increase due to the on/off cycle of the automatic defrosting system. The temperature was also more than 10°C higher than the mean registered value, and leads to a partial warming of the product. This undesired effect appears less important when the distance of the probe is higher respect to the air-cooler. Data concerning the probes placed on the container floor demonstrated a good result in terms of temperature homogeneity, but temperature reached a minimum level of about -0,8°C (when the cooling system started) which can be considered too low for orange fruits storage, due to the risk of cold damage rising (about -1,0°C). Vented boxes allow a more rapid cooling and a more accurate temperature control, probably due to the presence of the vent openings and, consequently, the less thermal resistance. Indeed citrus fruits placed in the vented boxes show a temperature variation like the environment cold air, while the fruits in the classic boxes show a great inertia to modify their temperature. Therefore, using the vented boxes need a precise control of the container air temperature, as any air temperature fluctuation can lead to a fruit quality decrease. The container for citrus fruit transport has to be suitable for cooling; every container for food freezing is not suitable for the scope; indeed the low evaporation temperatures could lead the rising of fruit cold damages.