Preparation of B-Cyclodextrin-Thiabendazole-Piperonyl Butoxide Supramolecular Complex and its Activity against Blue and Green Mould Decay on Inoculated Satsuma Fruit

The supramolecular complex of ?-cyclodextrin-thiabendazole-piperonyl butoxide (?CD-TBZ/PBO) was prepared and its structure was characterized by 1H NMR. Additionally, the antifungal activity of ?CD-TBZ/PBO was investigated in comparison with the commercially available thiabendazole (TBZ) fungicide by both in vitro tests and after application on artificially inoculated 'Okitsu' satsuma fruit at room temperature (20°C) or at 50°C to control postharvest blue (Penicillium italicum) and green mould (P. digitatum). Results of this study showed that ?CD-TBZ/PBO is stable for several months when stored as powder in dark bottle. At pH 7.0 water solubility of the ?CD-TBZ/PBO complex was consistently higher than free TBZ. Water dip at 20°C did not affect the incidence of lesions caused by blue mould but favoured the development of green mould during 4-8 days of storage at 20°C with respect to untreated (control) fruit. Water at 50°C effectively reduced the incidence of blue mould and totally suppressed green mould during the first 4 days but lost its efficacy afterwards. By contrast, both TBZ and ?CD-TBZ/PBO had a lasting effect and were equally effective in controlling green and blue mould decay when applied at 20°C and 60 mg L-1 active ingredient (a.i.). When applied at 50°C and 20 mg L-1 a.i. the activity of the complex against blue mould was inferior than the corresponding treatment with TBZ. In vitro assays revealed a significant effectiveness of ?CD-TBZ/PBO complex at low concentration compared to commercial formulation of TBZ.