Transit Refrigeration of Perishables in Overseas Van Container Shipments

Transit times for shipments of lettuce, oranges, and honeydew melons, made by ocean carrier from California to Japan and Hong Kong, were 10 and 15 days, respectively. Refrigerated van containers with constant air circulation through the load and a mechanism for reducing refrigeration capacity as the temperature approached the thermostat set point had an average temperature spread of only 2° Fahrenheit (1.1° Celsius) throughout the load from the second day of transit until arrival at destination ports. In two other refrigeration systems without these features, temperature variation throughout the loads averaged 4° F (2° C) and 10° F (6° C) during the same time period. The carbon dioxide levels averaged about 2 percent in the two van loads of oranges and ranged from 0.5 to 1.5 percent in the remaining containers during shipment. A van container designed to maintain controlled atmospheres during transit failed to hold the oxygen concentration at 5 percent, as intended. Arrival quality of the lettuce and honeydew melons was impaired because of variation in maturity of individual heads or melons within cartons, which resulted in physical damage to the lettuce and an excessively wide range of degree of ripeness of the melons.