Effect of cyclic exposure to ozone gas on physicochemical, sensorial and microbial quality of whole and sliced tomatoes

The effect of a humidified flow of ozone-enriched air applied cyclically (4 ± 0.5 μL L−1 of O3 for 30 min every 3 h) on metabolic behaviour and sensorial and microbial quality of whole and fresh-cut ‘Thomas’ tomatoes stored up to 15 days at 5 °C was examined. The application of O3 initially stimulated the respiration rate in a way similar to a stress, although after 2 days, the metabolic activity decreased to a rate lower than that of control (air flow). In O3-treated whole and sliced tomatoes a higher sugar (fructose and glucose) and organic acid (ascorbic and fumaric) content was found. The kind of cut (whole or slices) did not affect the sensitivity of tomato to O3. In whole tomatoes, O3 maintained the tissue firmer than in control fruit while no influence was found on slices. The O3 treated fruit retained a good appearance and overall quality in slices but experienced a reduced aroma. Also, O3 substantially reduced microbial counts, being more noticeable on bacteria (1.1–1.2 log10 units) than on fungi (0.5 log10 units). This effect was higher when the storage time was longer and when a higher O3 level (7 μL L−1) was used. O3 did not cause any damage or off-flavour in slices or whole tomatoes. In conclusion, the assayed O3 treatment can be useful for maintaining quality and reducing microbial populations in whole and sliced tomato.