The effect of calcium ascorbate on fruit firmness, cell wall-degrading enzymes activities and postharvest quality of tomato cv. Rio Grande

In this research, the effects of calcium ascorbate (CaA) on storage life of tomato cv. Rio Grande (harvested at color breaking stage) was investigated during 40 days of storage. This study was conducted as a factorial experiment in a completely randomized design with 3 levels of CaA (0, 0.25% and 0.5%) and 4 levels of storage periods. Fruits were dipped in CaA solutions and after drying in room temperature, were transferred to cold storage at 13±1°C. 10, 20, 30 and 40 days after storage, some qualitative parameters, color indices and activities of polygalacturonase and pectin methylesterase enzymes were measured. Results showed that calcium content of treated fruits with 0.25% and 0.5% of CaA were 20 and 23% higher than controls, respectively. The firmness of 0.5% CaA treated fruits had less reduction (13%) during storage in comparison with untreated fruits. L* and pectin methylesterase enzymes of treated fruits with both concentrations were 3% and 29% less than control fruits, respectively. CaA treatments had not significant effects on color indices (a*, b*, Chroma and Hue angel), pH, TA, TSS, vitamin C, carotenoids and polygalacturonase enzyme activity, but storage time affected all measured parameters except TA. Generally, results suggest that CaA have potential in maintaining firmness and quality of stored tomato by increasing calcium contents of fruits and decreasing activity of pectin methylesterase enzyme.