Antibacterial Effect of Various Essential Oils against Pathogens and Spoilage Microorganisms in Fresh Produce

Abstract

This study was conducted to investigate the antibacterial effect of various essential oils (EOs) against pathogens and fresh produce spoilage bacteria using the agar disc diffusion method and 96-well dilution method. Moreover, the antibacterial effect of EOs to reduce the level of total mesophilic microorganisms in fresh leaf lettuce and radish sprouts was determined by dipping method. Furthermore, membrane damage of two pathogens before and after treatment with effective EOs was determined using the fluorescent dye propidium iodide (PI) staining method. The results showed that thyme-1, thyme-2 and tea tree-2 oils demonstrated the strongest antibacterial effect against 18 strains of pathogens, except for Pseudomonas aeruginosa, in the agar disc diffusion method. Thyme-1 oil showed the strongest antibacterial effect against spoilage bacteria. The dipping treatment results showed that oregano-2 oil was the most effective at maintaining reduced levels of total mesophilic microorganisms in fresh produce compared with control, although it affected the quality of both vegetables after treatment. The results showed that treatment with clove bud, cinnamon-2 and oregano-2 oils led to PI values significantly greater than that of untreated cell. Practical Applications Natural essential oil solutions can be used for the disinfection of fresh produce as an alternative to chlorine, and oregano oil could be used as an alternative to synthetic sanitizers, classically applied in fresh produce.