STORAGE OF MINIMALLY PROCESSED ROMAINE LETTUCE UNDER CONTROLLED-ATMOSPHERE

The effects of CO2 and O-2 concentration on the preservation of minima lly processed Romaine lettuce (Lactuca sativa, L.) under controlled at mosphere were studied. The lettuce was stored at 4C for 16 days under a continuous stream of nitrogen containing 0.5 to 2% O-2 and 2 to 15% CO2. Increasing the CO2 content in the atmosphere to 10% or more reduc ed enzymatic browning due to wounding and improved lettuce visual qual ity. However, 15% CO2 caused brown lesions (brown stain, BS) after 8 d ays of storage. Decreasing the O-2 content to 1% in the presence of 10 % CO2 reduced tissue browning slightly without lowering the content of phenols, but 0.5% O-2 increased browning and anaerobiosis. Among the atmospheres tested, 10% CO2 and 1% O-2 were beneficial for maintenance of the quality of minimally processed Romaine lettuce.