Thyme oil alginate-based edible coatings inhibit growth of pathogenic microorganisms spoiling fresh-cut cantaloupe

Abstract

Fresh-cut cantaloupe (Cucumis melo L.) is a popular food. However, the presence of foodborne pathogen on the cut surfaces leads to both spoilage and food poisoning of fresh-cut cantaloupe. The antibacterial effectiveness of an alginate-based edible coating (EC) containing thyme oil was evaluated against foodborne pathogens on fresh-cut cantaloupe samples. Cantaloupe samples were treated with alginate-based EC and alginate-based EC containing different concentrations (0, 0.05, 0.35, and 0.65%, v/v) of thyme oil. Uncoated samples served as the control. The viability of naturally occurring microorganisms and artificially inoculated foodborne pathogens on the fresh-cut cantaloupe samples, as well as cantaloupe respiration rate, weight loss, and colour, were determined every 4 days over 16 days at 4 °C. Results showed that alginate-based EC containing thyme oil effectively improved the quality of fresh-cut cantaloupe and prolonged its shelf life. The treatments inhibited the growth of naturally occurring microorganisms and artificially inoculated pathogens (Listeria monocytogenes, Staphylococcus aureus, Salmonella Typhimurium, and Escherichia coli O157:H7) on fresh-cut cantaloupe samples. Treatment with alginate-based EC containing 0.05% thyme oil did not affect the respiration, prevented weight loss, and maintained the colour and sensory characteristics of fresh-cut cantaloupe samples. Gram-negative bacteria (S. Typhimurium and E. coli O157:H7) were more resistant to alginate-based EC containing thyme oil than Gram-positive bacteria (L. monocytogenes and S. aureus). Therefore, the use of an alginate-based EC containing thyme oil might be a promising approach to increase shelf life and increase safety of fresh-cut cantaloupe.