Active modified atmosphere package induced a new physiological disorder of minimally processed romaine lettuce leaves

Active modified atmosphere (active MAP) is commonly used for browning control of fresh-cut lettuce. However, it induces a disorder which is first reported in this study, described as 'leaf collapse'. This study attempt to evaluate the possible factors involved in the development of this physiological disorder. Therefore, minimally processed romaine leaves of a sensitive and a resistant cultivar were stored under three different conditions (active MAP, passive MAP, air) for 6 days at 4 degrees C. The results showed that the development of leaf collapse was correlated with the interaction of cultivar and atmosphere composition. No correlation among leaf calcium content as well as leaf age with collapse index was recorded. On the contrary, results showed increased C2H4 production and membrane permeability of the sensitive lettuce cultivar as well as C2H4 accumulation in packages during storage under active MAP conditions compared to tolerant one.