Effect of modified atmosphere packaging on quality and shelf life of baby leaf lettuce

Abstract

Freshly harvested baby leaf lettuce (Lactuca sativa L. cv. Red Romaine) leaves were packaged with 1,300, 20,000, 40,000, or 100,000 cm(3)/m(2)/day/atm oxygen transmission rate (OTR) packaging films as modified atmosphere packaging (MAP), as well as perforated film, then stored at 8 degrees C with 90% relative humidity in order to determine the most suitable OTR film. The results indicated that the 20,000 cm3 OTR film modified the atmosphere created in the package so that it consisted of 19.25-19.95% oxygen, 1.55-4.90% carbon dioxide and 5.10-8.06 mu l/l ethylene. Changes in quality of the lettuce, including weight loss, visual quality, chlorophyll concentration, colour (L*, a*, b*, chroma and hue angle) and off-odour were lowest under the 20,000 cm(3) OTR film. Leaves under the 20,000 cm(3) OTR film also exhibited the highest shelf life at 30 days. The anthocyanin concentration was highest and the peroxidase activity, which results in browning, was lowest under the 20,000 cm(3) OTR film, compared with the other treatments. In the baby leaf lettuce, the antioxidant capacity was tested and measured as flavonoid, phenolic, 1,1-diphenyl-2-picrylhydrazyl and total vitamin C concentrations, all of which showed the highest concentrations under the 20,000 cm(3) OTR film. Therefore, the 20,000 cm(3) OTR film, as a MAP, could be useful for the cold chain distribution of baby leaf lettuce for maintaining quality and thus exporting lettuce for consumer satisfaction.