Postharvest management of decay on tomatoes using sulphur dioxide sheets

Postharvest losses of tomatoes due to decay and handling along the retail chain are immense and have an impact on the industry. As a commodity that is quick to market with a short shelf life, there is a need to focus on the postharvest preservation of tomatoes. The application of sulphur dioxide packaging has the potential to protect against postharvest decay-causing pathogens whilst maintaining fruit quality. Two tomato cultivars, ‘Round’ and ‘Roma’, were exposed to an SO₂ sheet applied as a top sheet or bottom sheet in standard 5 kg tomato cartons. The fruit was stored at 10°C for 14 and 21 days, each with respective shelf life storage at 18°C. The results indicate that SO₂ application successfully reduced natural decay development on ‘Roma’ tomatoes throughout the storage periods. Both applications reduced decay by more than 50% during the 14-day cold storage and subsequent shelf life. For long-term (21 days) cold storage of ‘Roma’ tomatoes decay was reduced with a bottom sheet application. A residual effect of the SO₂ application was evident during shelf life, with a significant reduction in decay on treated tomatoes. Only marginal decay control was observed on the ‘Round’ tomatoes and thus warrants further study. SO₂ damage occurred on tomatoes with the application of a bottom sheet. The damage on ‘Roma’ tomatoes was marginal (5.4%) but more on ‘Round’ tomatoes at about 16%. Overall, the SO₂ damage observed could be easily sorted and removed after cold storage as the damage does not develop further after shelf life.