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

Abstract

A photocatalytic reaction of TiO2 was studied as a possible method for ethylene decomposition in fruit andvegetable storage. Its effectiveness was clearly confirmed through both chemical analysis and a fruit storage test.Photooxidation of ethylene by TiO2 was examined using TiO2coated glass beads and a TiO2 solution in both closed and flowsystems, which were irradiated with a blacklight fluorescent lamp (300400 nm). Ethylene concentrations decreased inresponse to TiO2 photocatalyst treatment, while those of the control (without TiO2 photocatalyst) and of the system treatedwith TiO2 under dark conditions remained constant. Our results indicate that the photocatalytic reaction of TiO2 to decomposeethylene can be carried out under high humidity at both room temperature and low temperature, and under both normalairand modifiedatmosphere conditions, without excessively increasing the temperature of the storage air. In addition, in thefruit ripening test under modified atmosphere conditions at 90% to 95% RH, a photocatalytic reaction of TiO2 successfullydelayed the ripening of green tomatoes into red tomatoes. No ethylene gas was found in the storage atmosphere under theTiO2 reaction condition throughout the experimental period. The exposure of tomato fruit to UVA resulted in no symptomsof disorder when the fruits ripened. The results suggest that use of TiO2 photocatalytic technology may be useful in fresh fruitand vegetable postharvest storage.