Use of ionizing radiation to ensure the safety of pre-cut fresh vegetables

The determination of D10 values for two Escherichia coli strains (an ATTC and a wild type), Listeria innocua, and a non toxigenic strain of Escherichia coli O157:H7 was carried out in different vegetal products. The studied products -celery (Apium graveolens), cabbage (Lactuca sativa var. capitata), iceberg lettuce (Lactuca sativa var. capitata), carrots (Daucus carota L.), spinach (Spinacia oleracea) and two mixed salads (Toscana, containing chopped iceberg lettuce (Lactuca sativa var. capitata), red cabbage (Brassica oleraceae var. rubra) and shredded carrot (Daucus carota L.) and Four Seasons, a mixture of chopped romaine lettuce (Lactuca sativa var. longifolia), iceberg lettuce (Lactuca sativa var. capitata), Butterhead lettuce (Lactuca sativa var. acephala) and spinach (Spinacia oleraceae) - were minimally processed. The effect of irradiation with 5 D10 doses on the natural microflora and on the sensory characteristics, during refrigerated storage, of the non inoculated products, was also studied. After irradiating with 5 D10 doses, a considerable reduction in the initial contamination of the studied vegetables was obtained. No significant variation of the microbiological counts of the irradiated products was observed during the refrigerated storage, while in the non-irradiated samples a progressive increase up to 3.5 logs in some vegetables was observed. In general, no significant changes in the sensory parameters were observed after irradiation and during seven days storage at refrigeration temperature (4 deg. C). (author)