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Abstract
This publication describes the results of 14 test shipments of California naked-packed and wrapped iceberg lettuce shipped in a highway refrigerated trailer modified with a 3-inch-(7.6 cm) deep floor and 0.75-inch (1 .9 cm) wall battens. The trailer was equipped with a conventional refrigeration unit or with a bottom-air-delivery refrigeration unit. On arrival at eastern markets, naked-packed lettuce loaded directly on the floor of a trailer with the conventional refrigeration system had a temperature spread of 15°F (8.3°C) compared with a spread of 11°F (6.1°C) for lettuce in a trailer with the bottom-air refrigeration system. The maximum lettuce temperature on arrival was 4°F (2.2°C) lower in the trailer with the bottom-air-delivery system than that in the trailer with the conventional system. For wrapped lettuce loaded on pallets in the trailer with the conventional refrigeration system, the temperature range on arrival was 19°F (10.6°C) compared with 14°F (7.8°C) in the trailer with the bottom-air-delivery system. The maximum lettuce temperature on arrival was 5°F (2.8°C) lower in the trailer with bottom-air-delivery than in the other type of trailer.