The combined effects of ultraviolet-C irradiation and modified atmosphere packaging for inactivating Salmonella enterica serovar Typhimurium and extending the shelf life of cherry tomatoes during cold storage

The combined effects of ultraviolet-C (UV-C) irradiation, modified atmosphere packaging (MAP), and cold storage temperature on the quality of inoculated (Salmonella enterica serovar Typhimurium) and non-inoculated cherry tomatoes were investigated. Based on the inactivation and sublethal injury tests of S. Typhimurium by UV-C irradiation, 2 kJ/m(2) UV-C was selected for the combined treatment. Non-inoculated and inoculated cherry tomatoes were irradiated with 2 kJ/m(2) UV-C and then packaged under two different modified atmosphere conditions (passive and active) and stored for 9 d at 4 and 20 degrees C. As controls, non-irradiated cherry tomatoes packaged in perforated film bags were stored. When the inoculated cherry tomatoes that were irradiated with UV-C were packaged under an active modified atmosphere (5.3% CO2 + 5.5% O-2), the S. Typhimurium populations were significantly reduced during storage at 4 degrees C compared to those of other treatments. Regarding the color, the combination of UV-C and active MAP delayed the change of Hunter b* and Delta E values in cherry tomatoes during storage at 4 degrees C. Regardless of treatment and packaging method, the cherry tomatoes stored at 4 degrees C exhibited a lower decrease of firmness compared to those stored at 20 degrees C. After 9 d of storage at 4 or 20 degrees C, there were significant differences in lycopene content and weight loss depending on storage temperature or gas composition in packaging film. Therefore, these results suggest that the combination of UV-C irradiation and active MAP can improve the microbial safety and extend the shelf life of cherry tomatoes during cold storage. (C) 2014 Elsevier Ltd. All rights reserved.