Synergistic effect of essential oils and enterocin KT2W2G on the growth of spoilage microorganisms isolated from spoiled banana peel

The deterioration of fresh food by spoilage microorganisms remains a significant problem even though a diversity of preservation approaches has been proposed. The consumer's choice is demanding for chemical and antimicrobial-free products, which has prompted the development of natural alternatives to retard food spoilage. This study was performed to evaluate the effect of the combination of essential oils (EOs) (orange, tea tree, citronella grass and cinnamon) and enterocin KT2W2G against spoilage microorganisms isolated from the surface of spoiled banana (Musa ABB cv. Kluai “Namwa”) peel by using the agar well diffusion assay. Eighteen spoilage microorganisms (9 strains of bacteria and 9 strains of yeast) were selected as indicator strains. They were identified based on partial 16S rDNA and 18S rDNA gene sequencing for bacteria and yeast, respectively. Selected spoilage bacteria were identified as Lactococcus lactis subsp. lactis, Enterococcus faecalis, Klebsiella pneumonia, Klebsiella variicola and Serratia marcescens, whereas selected spoilage yeast were identified as Kodamaea ohmeri, Pichia aff. fermentans, Pichia kudriavzevii, Hanseniaspora opuntiae and Candida metapsilosis. The agar well diffusion assays resulted in cinnamon as being the most effective EO against selected spoilage indicator. The combination of cinnamon oil and enterocin KT2W2G at 6:4 ratios exhibited the best synergistic effect against selected spoilage microorganisms, whereas enterocin KT2W2G applied as single substance displayed no activity. The results obtained indicate that the combination of cinnamon oil with enterocin KT2W2G harbours the potential to be used as a natural biocontrol agent to improve food quality and to extend the shelf life of harvested bananas.