Chemical compositions and antibacterial activities of essential oils extracted from Alpinia guilinensis against selected foodborne pathogens

Concerns about the use of synthetic preservatives during food processing and storage have been raised due to their potential side effects on human health and the environment. The chemical compositions, bactericidal activities and mechanism of Alpinia guilinensis essential oils (EO) hydrodistilled from fruits, leaves and stems were investigated as a potential substitute for synthetic preservatives for the first time, respectively. The diameter of inhibition zone (DIZ), minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC) of three EOs against four foodborne pathogenic bacteria (Staphylococcus aureus, Bacillus subtilis, Escherichia coli, Pseudomonas eruginosa) indicated their broad-spectrum and strong antibacterial activities. Notably, three EOs showed obvious effects on S. aureus and the DIZ of leaves essential oil (16.8 mm) against S. aureus was close to that of antibiotic streptomycin (18.3 mm). The antibacterial mechanism of A. guilinensis EOs differed from streptomycin on the basis of scanning electron microscopy (SEM) and transmission electron microscopy (TEM) observations. A. guilinensis EOs may increase bacterial membrane permeability and directly break cell structure, leading to bacterial shrinkage and lysis. The low hemolytic rates (below 1%) of three EOs on human red blood cells (RBC) further suggested their safety for use. Taken together, the essential oils of A. guilinensis may provide natural and safe preservatives in food processing and storage. (C) 2015 Elsevier B.V. All rights reserved.