A demanda por frutas e hortaliças frescas, associada à necessidade de maior praticidade da vida atual, está incentivando o interesse dos consumidores por produtos minimamente processados. Entre os microrganismos patogênicos que podem ser transmitidos por estes vegetais encontram-se principalmente Listeria monocytogenes, Escherichia coli O157:H7 e Samonella spp. Alguns métodos são utilizados para prevenir e controlar estes microrganismos, entre eles, a irradiação. Amostras de agrião (Nasturtium oficinallis) minimamente processado foram inoculadas com uma mistura de três cepas de Salmonella (Salmonella Infantis, Salmonella Enteritidis ATCC 13076, Salmonella Tiphymurium ATCC 14028) e expostos às doses de 0; 0,2; 0,5; 0,7; 1,0; 1,2 e 1,5 kGy. O valor D₁₀ para Salmonella spp inoculada em agrião minimamente processado submetido à radiação gama variou de 0,29 a 0,43 kGy. Amostras de agrião expostas a doses de 1, 3 e 4 kGy e amostra testemunha, mantidas sob refrigeração, foram utilizadas para avaliação sensorial e vida-de-prateleira. Todas as amostras expostas à radiação foram aceitas pelos julgadores. A vida-de-prateleira da amostra de agrião exposta à 1 kGy foi de 16 dias, um dia e meio a mais que a testemunha. A vida-de-prateleira das amostras expostas à 3 e 4 kGy foi de 9 e 6 dias, respectivamente.

Consumer attitudes towards foods have changed in the last two decades increasing requirements for freshlike products. Consequently less extreme treatments or additives are being required. Minimally processed foods have freshlike characteristics and satisfy this new consumer demand. Besides freshness, the minimally processing also provide convenience required by the market. Salad vegetables can be source of pathogen such as Salmonella, Escherichia coli O157:H7and Listeria monocytogenes. The minimally processing does not reduce the levels of pathogenic microorganisms to safe levels. Therefore, this study was carried out in order to improve the microbiological safety and the shelf-life of minimally processed vegetables using gamma radiation. Minimally processed watercress inoculated with a cocktail of Salmonella spp was exposed to 0.0, 0.2, 0.5, 0.7, 1.0, 1.2 and 1.5 kGy. D₁₀ values for Salmonella spp inoculated in watercress varied from 0.29 to 0.43 kGy. Samples of watercress exposed of 1, 3 e 4 kGy and non-irradiated sample, stored at 7°C, were submitted to sensory evaluation and their shelf-life was determined. All samples were accepted by members of sensory panel. The shelf-life of sample irradiated with 1 kGy was 16 days (one and half day more than shelf-life of non-irradiated sample) and samples exposed to 3 and 4 kGy presented shelf-life of 9 and o days, respectively.