Constituents of the essential oils of garlic and citronella and their vapor-phase inhibition mechanism against S.aureus

Abstract

The purpose of this study was to evaluate the vapor-phase antibacterial efficacy of garlic essential oil (GEO) and citronella essential oil (CEO) against four foodborne bacteria and their vapor-phase antibacterial mechanism against Staphylococcus aureus (S.aureus). GC-MS analysis confirmed that diallyl disulfide (29.258 %) and citronellal (36.940 %) were the major constituents of GEO and CEO, respectively. GEO and CEO at concentrations of 80 μL/L could completely inhibit the growth of all tested bacteria and the combinations of GEO with CEO displayed additive effects against the four tested bacteria with fractional inhibitory concentration index (FICI) values of 0.75 or 0.50. Furthermore, the scanning electron microscopy observations, the change of proteins concentration and catalase activity of S.aureus confirmed that the EOs impacting the membrane integrity and catalase activity of S.aureus. Thus, our study will provide a theoretical foundation for the applicability of EOs on the non-contact preservative packaging for food.