Kraft paper boxes containing 10 expanded polystyrene trays with 200g skinless deboned chicken breast each were irradiated with 60Co source of a Nordion JS7500 irradiator. The trays were previously wrapped with polyethylene film. The samples were exposed to 1.5; 3.0 and 7.0 kGy doses in the static mode at 0º and 180º in relation to the irradiation beam. Set of 18 alanine+paraffin dosimeters per treatment were distributed inside the boxes for evaluation of irradiation dose homogeneity. A separeted dose calibration curve was obtained by irradiating in the range of 1 to 10kGy. After the irradiation, the chicken breasts were stored at 5±1ºC for 39 days and were analysed microbiologically in total psychrotrophic aerobic bacteria, total mesophilic aerobic bacteria, molds and yeasts, Pseudomonas spp, Enterobacteriaceae, lactic bacteria counts and E.coli during the storage period. The results revealed a linear behaviour of the alanine+paraffin dosimeters in the range of 1 to 10kGy irradiation. In regard to the microbiological aspect, compared to the shelf-life of 5 days for the controls, there were a increasing of 1.75; 4.40 e 7.0 times shelf-life for chicken breasts irradiated with 1.5; 3.0 and 7.0kGy, respectively. There was an increasing change of the smell of burnt as the irradiation doses increased. Thus, 3kGy dose was considered as the ideal dose to assure a longer shelf-life to the product, without perceptible changes in the aspect.
chicken breast; irradiation; dosimeters; microbiology; sensory evaluation
