Effects of low-dose gamma irradiation on the shelf life and quality characteristics of cut romaine lettuce packaged under modified atmosphere

Cut romaine lettuce, packaged under modified atmosphere, was subjected to 0 .15 and 0.35 kGy gamma irradiation. Irradiation at 0.35 kGy decreased aerob ic plate counts by 1.5 logs and yeast and mold counts by 1 log; these diffe rences were maintained through the 22-d storage. Irradiation at 0.15 kGy ca used smaller reductions in microbial counts. A decrease in headspace CO2 wa s observed in the 0.35-kGy-treated lettuce, although CO2 concentrations inc reased in all samples with storage. O-2 concentration was not affected by i rradiation. Ten percent loss in firmness was observed at 0.35 kGy, while ot her sensory attributes such as color, generation of off-flavor, and appeara nce of visual defects were not affected.