Combination of ultraviolet light-C and clove essential oil to inactivateSalmonellaTyphimuriumbiofilms on stainless steel

Salmonella typhimuriumis able to form biofilms as a resistance mechanism against antimicrobials; therefore, it represents a problem for assuring food safety and highlights the importance of research on anti-biofilm technologies. In this study,S. typhimuriumbiofilms were inactivated with the combination of clove essential oil (CEO) and ultraviolet light (UV-C). The volatile composition of the CEO determined by gas chromatography showed eugenol as the major constituent (82%). A combination of CEO with UV-C achieved a complete bacterial reduction (6.8 log/cm(2)) on biofilms with doses of 1.2 mg/ml and 76.41 mJ/cm(2), respectively. Individually, the CEO at 1.2 mg/ml caused a reduction of 1.8 log CFU/cm(2)of attached bacteria cells on stainless steel, while UV-C individually used at 620.4 mJ/cm(2)caused a 2.9 log CFU/cm(2)reduction compared to control biofilms. In conclusion, this study demonstrated a synergistic effect of combining CEO and UV-C irradiation to inactivate biofilms ofS. typhimurium.