Antimicrobial activity of citrus oil against Salmonella and Escherichia coli growth

This study evaluated the effectiveness of citrus oil, to be used as eco-friendly detergent to wash fresh-cut produce, on reducing the growth of Escherichia coli and Salmonella. The experiments were carried out by varying the concentrations of lemon oil or lime oil (0.1 to 0.5 v/v) in flasks containing nutrient broth. Escherichia coli and Salmonella were inoculated into the flasks (10(6) CFU mL(-1)), in which they were incubated at 37 degrees C for 24 h. Samples were withdrawn every 20 min until 1 h and after 24 h. The colonies were determined after a sequential of sample dilutions (1: 10) in peptone water that have been spread (100 mu L) on the agar plates for incubation at 37 degrees C for 24 h. Within the range studied, the optimal concentration to inhibit E. coli growth was 0.3 to 0.5% of lime oil, while to combat Salmonella the best condition was 0.15 to 0.3% of lime oil, combined with citric acid. Salmonella was more susceptible to lime oil than E. coli. No antimicrobial synergistic action between lime and lemon oil (p<0.05) was observed.