The effect of electron beam irradiation on microbiological quality and safety of fresh-cut tomatoes was studied. Fresh tomatoes were obtained from a local supplier and then cut into cubes that were separated from the stem scars. Both cubes and stem scars were inoculated with a rifampin-resistant strain of either Salmonella Montevideo or Salmonella Agona, separated into treatment groups, and treated by electron beam irradiation at 0.0 (control), 0.7, or 0.95 kGy. The effect of electron beam irradiation on Salmonella, lactic acid bacteria, yeast, and mold counts and pH of tomato cubes and stem scars was determined over a 15-day storage period at 4 degrees C. Results indicated that although irradiation treatment significantly reduced most microbial populations on tomato samples, there were no differences in the reduction of microbial populations between treatments of 0.7 and 0.95 kGy. Irradiation at either dose resulted in a significant reduction in Salmonella when compared with the control (P < 0.05). Lactic acid bacteria, yeasts, and molds were more resistant to irradiation than were Salmonella. No differences were detected between the two Salmonella serotypes in response to irradiation treatment. These results indicate that irradiation at doses of at least 0.7 kGy can be used for pathogen reduction in fresh-cut tomatoes. If the use of doses greater than 1 kGy were approved, this technology might be very effective for use in fresh-cut tomatoes to eliminate significant populations of pathogens and to ensure the microbial quality of the product.

Electron beam irradiated sliced cantaloupe was tested for 21 d of storage for total aerobic microbial counts, texture, color, and different sensorial parameters as a function of irradiation doses 0, 0.7, and 1.4 kGy and the wash treatments, 1 and 200 ppm chlorine applied to the melons before cutting. Irradiation resulted in a reduction in the total aerobic microbial counts with increasing doses. Melons washed only with water before cutting had total aerobic bacterial counts of 4.0, 2.0, and 0.8 log colony-forming units (CFU)/g on day 0 at irradiation doses of 0, 0.7, and 1.4 kGy, respectively. Across all doses of irradiation, counts were consistently lower for cantaloupe pieces obtained from melons that had been subjected to chlorine rinse in comparison with those washed with water without chlorine. Melons washed with chlorine before cutting had total aerobic bacterial counts of 2.7, 0.7, and 0.5 log CFU/g on day 0 at irradiation doses of 0, 0.7, and 1.4 kGy, respectively. Objective color analysis indicated no significant effect of irradiation on the color of cantaloupe. Texture measured as compression force was lower only for cantaloupe irradiated at 1.4 kGy. Irradiation did not affect descriptive attribute flavor and texture sensory attributes of cantaloupe pieces. Decontamination of whole cantaloupes before cutting using chlorine wash may be combined with low-dose irradiation for shelf-life extension of sliced cantaloupe.

No abstract