Antifungal activity of TiO2 photocatalysis against Penicillium expansum in vitro and in fruit tests

The antifungal activity of TiO2 photocatalytic reaction in the form of TiO2 powder and TiO2 coated on a plastic film against Penicillium expansum was investigated in vitro and in fruit tests. The mixture of P. expansum conidial suspension and TiO2 powder was added to potato dextrose agar (PDA) plates for vitro test. The TiO2 photocatalytic reaction reduced conidial germination of the fungal pathogen. It was found that the ability of the TiO2 photocatalytic reaction to suppress P. expansum growth correlated to the amount of TiO2 added. Lower numbers of viable colonies of P. expansum were observed with increasing amount of TiO2. Regardless of the kind of selected fruit inoculated with P. expansum, both TiO2 powder and TiO2-coated film exhibited antifungal activity to control fruit rot. Development of Penicillium rot in apple was significantly (P = 0.05) retarded by the TiO2 photocatalytic reaction. Similarly the TiO2 photocatalytic reaction was the only treatment where no tomato fruit rot was noticeable after 1 week of storage. TiO2-coated film also decreased brown lesions and Penicillium rot infection in lemons. The mean severity fruit rot scores (browning and softening flesh) were 3.2 and 1.9 for uncoated and TiO2-coated film, respectively. Our findings suggest that “TiO2 photocatalytic reaction” shows antifungal activity against P. expansum which may have potential for postharvest disease control.