Transit Temperatures of Iceberg Lettuce Shipped in Pallet Bins

Transit temperatures of western iceberg lettuce packed in bulk bins were determined in four test shipments of fully loaded trailers. Air temperatures in the four loads ranged from a high of 43°F (6.1°C) to a low of 24°F (-4.4°C); lettuce temperature averaged less than 40°F (4.4°C). The lowest lettuce temperatures were at the rear of the trailer where the air returns to the refrigeration unit. Heads of lettuce in the top layer bins were slightly cooler than those in the bottom layer bins. All lettuce temperatures were in an acceptable range during the tests, although not as close to the thermostat setting of 34°F. (1.1° C) as would be desirable.