Optimized preparation of tea tree oil complexation and their antifungal activity against Botrytis cinerea

Abstract Tea tree oil (TTO) inclusion complexes were prepared by co-precipitation with β-cyclodextrin (β-CD). After the complexation protocol was optimized using response surface methodology, the physicochemical and anti-fungal properties of the TTO-β-CD inclusion complex were investigated. The optimal complexation time (4 h), temperature (62 °C), and β-CD/TTO mass ratio (7), provided a TTO complexation efficiency of 87.47 %. Fourier transform infrared spectroscopy showed that the spectra of TTO complexations and β-CD are quite similar, suggesting that TTO molecules enter β-CD cavities during the formation of inclusion complexes. Scanning electron micrographs revealed that particles of TTO-β-CD complexes are smoother and smaller than the amorphous structures of β-CD. Thermogravimetric analysis demonstrated that the thermal stability of TTO is enhanced after complexation with β-CD, which reduces TTO volatility and oxidation. Complexed TTO inhibit mycelial growth of B. cinerea in a dose-dependent manner in vitro. In cherry tomato fruit, complexed TTO can control artificially-induced B. cinerea infection and extend shelf life. It was concluded that TTO complexation might be benefit for the commercial application of TTO to control the postharvest grey mold of fruits.