Fresh cut lettuce (Lactuca sativa L.) quality as affected by packaging material

The use of fresh cut vegetables has continued to increase in salad bars and fast food restaurants. Their storage life is influenced by their continued respiration and the biochemical activity associated with senescence. Enzymatic browning is one of the main causes of quality losses during postharvest storage. The combined use of modified atmosphere packaging and low temperature reduces respiration and delays senescence, thereby extending storage fife. The objective of this work was to assess the suitability of a range of polymeric films for modified atmosphere packaging on butterhead, crisphead, latin and leafy lettuce types minimally processed during storage at 4 degreesC for 9 days. Multilayered polyolefin RD-106, PD-900 and PD-961EZ films with different gas permeability (oxygen permeability from 3000 to 11500 cm(3) m(2) 24 h, 1 atm at 22.7 degreesC, carbon dioxide permeability from 9800 to 30000 cm(3) m(2) 24 h, 1 atm at 22.7 degreesC) were tested. Phenylalanine ammonia lyase (PAL), polyphenol oxidase (PPO) and peroxidase (POD) activities, and the content of phenolic compounds were measured to relate them to overall visual quality, leaf edge browning and leaf surface browning. The variability in enzymatic activity was affected by both the type of lettuce and the permeability of the packaging material for O-2 and CO2. A low chlorogenic acid concentration and the best organoleptic quality was achieved with the packaging material PD 900. The leafy lettuce type had the highest concentration of chlorogenic acid without quality losses by enzymatic browning. Leafy lettuce packed with multilayered polyolefins mantained an acceptable quality for consumption after 9 days of storage, independent on the polymeric film used as packaging material.