Biochemical changes and sensory quality of shredded and MA-packaged iceberg lettuce

Cultivars of shredded iceberg lettuce (Lactuca sativa L.) 'Saladin', 'Santis', 'Telda' and 'Roxette' responded in a parallel way to four modified atmosphere (MA) packaging treatments. Moderate vacuum packaging (mvp) in 80 mu m polyethylene (PE) inhibited enzymatic browning over 10-day storage at 5 degrees C. When lettuce was packaged in 80% O-2, 20% CO2 (80/20), more browning occured in SL3-bags (59 mu m multilayer coextruded film) than in PE-bags. Polyphenol oxidase activity declined during storage in all 4 atmospheres, with lowest activity in PE-80/20. Endogenous ascorbic acid (AA) did not act as an efficient antioxidant in delaying browning. Total carbohydrate content (TC) declined slightly during storage. Tristimulus color measurements correlated highly with visual ratings.