Fast screening method for assessment of antimicrobial activity of essential oils in vapor phase

Abstract

Among promising alternative methods to control food spoilage much attention is being paid to the use of essential oils (EOs), and lately also to their activity in vapor phase. Until now, no standard assay exists, and there are many methods used by different authors, but any of them is suitably adapted for fast screening of large quantities of samples. We have modified most commonly used disc volatilization method by using four-section Petri dish (PD, 90mm diameter), large filter paper disc (85mm diameter) evenly impregnated with EO and medium containing lid. In comparison to normal disc volatilization method, labor and material needed are several times reduced, while the composition of headspace is more uniform than in case of 6mm disc, where different volatility of particular compounds could influence the results. Sixty nine EOs were tested for its antimicrobial activity against three bacteria (Staphylococcus aureus, Salmonella enteritidis, Pseudomonas aeruginosa) and three fungi (Alternaria alternata, Aspergillus niger, Penicillium digitatum). Thirty nine EOs inhibited at least one microorganism, Armoracia rusticana and Cinnamomum zeylanicum being the most active, followed by EOs of Eugenia caryophyllata, Origanum compactum, Origanum vulgare, Pimenta racemosa, Thymus serpyllum and Thymus vulgaris inhibiting all six or five microorganisms, respectively. According to our opinion, this method is suitable for screening of large quantities of samples for antimicrobial activity in vapor phase.