MODIFIED-ATMOSPHERE PACKAGING OF MINIMALLY PROCESSED LOLLO-ROSSO (LACTUCA-SATIVA) - PHENOLIC METABOLITES AND QUALITY CHANGES

The effect of modified-atmosphere packaging (MAP) on the amount of sol uble phenolics in, and the visual appearance of, white, green and red tissues of minimally processed ''Lollo Rosso'' lettuce were evaluated. Minimal processing induced a two-fold increase in the amount of solub le phenylpropanoids in the midribs during storage in air at 5 degrees C. When the lettuce was stored in the presence of 2-3% O-2 and 12-14% CO2, this increase was not induced and no browning was observed. A par ticularly marked decrease in the amount of phenylpropanoids was observ ed in MAP-stored green and red tissues. The concentrations of flavonoi ds and anthocyanins did not change much in midribs and green tissues, while they were significantly degraded in red tissues under MAP condit ions. MAP storage proved useful in the prevention of browning, the mai n cause of quality loss in minimally processed ''Lollo Rosso'' lettuce . However, MAP storage was not so beneficial for the preservation of t he quality of red tissues and? in fact, their overall visual quality, texture, aroma and macroscopic breakdown under MAP conditions were wor se than those of air-stored tissues.