EFFICIENCY OF TIO2 PHOTOCATALYTIC REACTION ON DELAY OF FRUIT RIPENING AND REMOVAL OF OFF-FLAVORS FROM THE FRUIT STORAGE ATMOSPHERE

Abstract

A titanium dioxide (TiO2) photocatalytic reaction treatment was applied to tomato fruit during storage toinvestigate the variation in the efficiency of this treatment for delaying ripening time and removing off-flavors in the storageatmosphere. Its efficiency was evaluated at various TiO2 concentrations and ultraviolet-A (UV-A, 315-400 nm) lightintensities during fruit storage. In this study, TiO2 was applied to the fruit storage chamber in the form of TiO2 slurry. Theresults presented here demonstrated that the presence of TiO2 and UV-A light can remove ethylene gas from the storageatmosphere and extend the ripening time of green tomatoes. The extent of ethylene removal and ripening delay due to the TiO2photocatalytic reaction depended on the TiO2 concentration and the UV-A light intensity. More than 90% of the ethylene gaswas removed when TiO2 was applied at 10 g/Land the UV-A light intensity was 5 W/m2. Reduction of the TiO2 concentrationand UV-A light intensity to 0.1 g/L and <0.01 W/m2, respectively, resulted in decreasing ethylene removal capacity. Suchconditions also mitigated the observed delay in ripening. The TiO2 photocatalytic reaction also successfully removedacetaldehyde (AA), ethanol (EtOH), and off-flavors (fermented or alcoholic odor) generated in the storage atmosphere from0 to 8 days of storage. However, toward the end of the storage period, by day 10, when the production of AA and EtOH fromtomatoes was higher, the TiO2 treatment was apparently less effective in removing off-flavors. This finding suggests thatproduce metabolism must be taken into consideration for effective utilization of the TiO2 photocatalytic reaction to improve storage life of fresh fruits and vegetables.