PHOTOCATALYTIC REACTION OF TIO2 TO DECOMPOSE ETHYLENE IN FRUIT AND VEGETABLE STORAGE

A photocatalytic reaction of TiO2 was studied as a possible method for ethylene decomposition in fruit and vegetable storage. Its effectiveness was clearly confirmed through both chemical analysis and a fruit storage test. Photooxidation of ethylene by TiO2 was examined using TiO2–coated glass beads and a TiO2 solution in both closed and flow systems, which were irradiated with a black–light fluorescent lamp (300–400 nm). Ethylene concentrations decreased in response to TiO2 photocatalyst treatment, while those of the control (without TiO2 photocatalyst) and of the system treated with TiO2 under dark conditions remained constant. Our results indicate that the photocatalytic reaction of TiO2 to decompose ethylene can be carried out under high humidity at both room temperature and low temperature, and under both normal–air and modified–atmosphere conditions, without excessively increasing the temperature of the storage air. In addition, in the fruit ripening test under modified atmosphere conditions at 90% to 95% RH, a photocatalytic reaction of TiO2 successfully delayed the ripening of green tomatoes into red tomatoes. No ethylene gas was found in the storage atmosphere under the TiO2 reaction condition throughout the experimental period. The exposure of tomato fruit to UVA resulted in no symptoms of disorder when the fruits ripened. The results suggest that use of TiO2 photocatalytic technology may be useful in fresh fruit and vegetable postharvest storage.