Effect of cold atmospheric plasma on antifungal activities of clove oil and eugenol against molds on areca palm (Areca catechu) leaf sheath

Abstract

An attempt to control the growth of Aspergillus niger, Penicillium sp., and Rhizopus sp., commonly found on the surface of the areca palm (Areca catechu) leaf sheath, by using clove oil and its main components (eugenol, linalool, and caryophyllene) at concentrations of 5–100 μl ml−1 both in vitro (agar dilution method) and in vivo (dip method) was enhanced by discharging cold atmospheric plasma at 40 W for 10 min. The results showed that the minimum inhibitory concentration (MIC) of clove oil and eugenol was reduced tenfold against all molds at concentrations of 10 μl ml−1 and 5 μl ml−1, respectively, after cold atmospheric plasma treatment. For the in-vivo assays, clove oil at 30 μl ml−1 and eugenol at 10 μl ml−1with cold atmospheric plasma could extend the protection against the growth of all molds on the surface of an areca palm leaf sheath from 14 days (control) to at least 12 wk at 25 °C. In addition, it was observed that eugenol was the main agent responsible for the antifungal activity of clove oil after plasma treatment. This study has demonstrated the good potential of using atmospheric plasma treatment to enhance antifungal activity of clove oil and to control molds on an areca palm leaf sheath.