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

摘要

A titanium dioxide (TiO ₂ ) photocatalytic reaction treatment was applied to tomato fruit during storage to investigate the variation in the efficiency of this treatment for delaying ripening time and removing off-flavors in the storage atmosphere. Its efficiency was evaluated at various TiO ₂ concentrations and ultraviolet-A (UV-A, 315-400 nm) light intensities during fruit storage. In this study, TiO ₂ was applied to the fruit storage chamber in the form of TiO ₂ slurry. The results presented here demonstrated that the presence of TiO ₂ and UV-A light can remove ethylene gas from the storage atmosphere and extend the ripening time of green tomatoes. The extent of ethylene removal and ripening delay due to the TiO ₂ photocatalytic reaction depended on the TiO ₂ concentration and the UV-A light intensity. More than 90% of the ethylene gas was removed when TiO ₂ was applied at 10 g/L and the UV-A light intensity was 5 W/m 2 . Reduction of the TiO ₂ concentration and UV-A light intensity to 0.1 g/L and 0.01 W/m 2 , respectively, resulted in decreasing ethylene removal capacity. Such conditions also mitigated the observed delay in ripening. The TiO ₂ photocatalytic reaction also successfully removed acetaldehyde (AA), ethanol (EtOH), and off-flavors (fermented or alcoholic odor) generated in the storage atmosphere from 0 to 8 days of storage. However, toward the end of the storage period, by day 10, when the production of AA and EtOH from tomatoes was higher, the TiO ₂ treatment was apparently less effective in removing off-flavors. This finding suggests that produce metabolism must be taken into consideration for effective utilization of the TiO ₂ photocatalytic reaction to improve storage life of fresh fruits and vegetables