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

Authors: WANG, LIN - University Of Leeds; Fan, Xuetong; Sokorai, Kimberly; Sites, Joseph

Submitted to: Food Control
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 3/20/2019
Publication Date: 3/28/2019
Citation: Wang, L., Fan, X., Sokorai, K.J., Sites, J.E. 2019. 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. Food Control. 103:9-20.
DOI: https://doi.org/10.1016/j.foodcont.2019.03.026

Interpretive Summary: Gaseous ozone has been studied for it efficacy in inactivating various microorganisms. However, there have been few studies dealing with quality, particularly nutrients, of fresh produce treated with gaseous ozone to enhance microbial safety. The present study was conducted to determine the efficacy of dry gaseous ozone in inactivating Salmonella on grape tomatoes and its impact on fruit sensory and nutritional quality during 21 days of storage at 10 C. Results demonstrated that high concentrations of gaseous ozone significantly reduced Salmonella population on tomatoes. However, loss of nutrients and deterioration in other quality attributes were observed during storage. Therefore, dry ozone may not be appropriate to enhance the microbial safety of grape tomatoes without compromising fruit quality. The information will be of value for other researchers to explore ways and conditions to minimize quality changes caused by the gaseous treatment.

Technical 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 stem scar and smooth surface inoculation with Salmonella enterica serovar Typhimurium were treated with 1.71, 3.43 and 6.85 mg per liter dry gaseous ozone (<10% relative humidity) for 2 or 4 hours. For quality studies, non-inoculated tomatoes treated with gaseous ozone under the same concentrations and durations and stored at 10 C for 21 days. 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 day 1, 7, 14, 21 of storage. Results showed that 6.85 mg per liter ozone for 2 and 4 hours treatments reduced Salmonella populations by approximately 2 log CFU per fruit 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 per liter ozone for 2 and 4 hours and 3.43 mg per liter for 2 hours on day 1 and 7 of storage. However, mold and yeast counts were not consistently affected by the gaseous ozone treatments. Ozone at concentrations of 3.43 and 6.85 mg per liter ozone for 4 hours negatively impacted the ratings of appearance and off-odor. In addition, the treatments significantly reduced firmness and decreased lycopene and vitamin C contents. Overall, our results indicated that dry gaseous ozone that achieved significant reductions of Salmonella populations caused deteriorations in the quality of grape tomatoes.