Safer prepared meals for immunocompromised patients and the general consumer by gamma irradiation

Ready-to-eat meals are commonplace nowadays in urban life. Many of them, minimally processed, could convey foodborne pathogens likely to cause diseases in the consumer, which is of concern to the normal population and even more so to immunocompromised patients. The feasibility of attaining microbiological decontamination at pasteurization levels of such foods by gamma irradiation was studied. Typical Argentine dishes were chosen after market surveys: cannelloni in tomato sauce, tomato and carrot salad with boiled egg, empanada, fruit salad in gelatin jelly with white cheese, ham and cheese sandwich, chicken and vegetable pie, custard, and bread pudding, in different packaging. Microbiological profiles of the meals were obtained and challenge tests with Listeria innocua or Salmonella enteritidis were performed to determine the minimum radiation dose to be applied in each food so as to attain a 6 log cycle reduction of pathogen counts. Preliminary sensory evaluations, out of panel, were carried out to determine possible evident sensory alterations due to the irradiation treatment. Then, a greater number of samples were irradiated at the minimum radiation dose and at a maximum dose equal to or less than twice the minimum, at the ⁶⁰Co semi-industrial facility of the Ezeiza Atomic Center. Microbiological and sensory analyses by a consumer panel were performed on control and irradiated samples throughout storage life at refrigeration temperatures. A whole irradiated lunch, composed of salad, empanadas and fruit salad, was sampled by 44 immunocompromised patients at a hospital. The composition and adequacy of this lunch was designed by nutritionists. Results showed that it was feasible to attain the proposed decontamination goal without significantly impairing the sensory quality. Shelf life was almost tripled in irradiated samples. Immunocompromised patients enjoyed the irradiated lunch and requested it and other dishes to be made commercially available. (author)