Quality deterioration of grape tomato fruit during storage after treatments with gaseous ozone at conditions that significantly reduced populations of Salmonella on stem scar and smooth surface

Abstract

Gaseous ozone was evaluated for its effectiveness in reducing populations of Salmonella and native microorganisms on grape tomatoes and its impact on sensory and nutritional quality of the fruit. Grape tomatoes with Salmonella enterica serovar Typhimurium inoculated onto stem scar and smooth surface were treated with 1.71, 3.43 and 6.85 mg L−1 gaseous ozone for 2 or 4 h. For quality studies, non-inoculated tomatoes were treated with gaseous ozone under the same concentrations and durations and stored at 10 °C for 21 d. Sensory properties (appearance and off-odor), total plate count (TPC), mold and yeast count, instrumental color, firmness, and lycopene and vitamin C content were measured on d 1, 7, 14, and 21 of storage. Results showed that 6.85 mg L−1 ozone for 2 and 4 h treatments reduced Salmonella populations by approximately 2 log CFU fruit−1 on both smooth surface and stem scar area of tomatoes. Other treatments did not significantly reduce the populations of Salmonella. Significant reductions on TPC were observed on fruit treated with 6.85 mg L−1 ozone for 2 and 4 h and 3.43 mg L−1 for 2 h on d 1 and 7 of storage. However, mold and yeast counts were not consistently affected by the gaseous ozone treatments. Ozone at 3.43 and 6.85 mg L−1 for 4 h negatively impacted the ratings of appearance and off-odor. In addition, the same treatments significantly reduced firmness and decreased lycopene and vitamin C contents. Overall, our results indicated that gaseous ozone that achieved significant reductions of Salmonella populations caused deteriorations in the quality of grape tomatoes.