Inhibitory synergism effect of citric acid, citrus oil and nisin on growth of Escherichia coli

The objective of this work was to evaluate the synergism effect of citric acid, lemon oil, lime oil and nisin as sanitizer to inhibit the growth of Escherichia coli, “in vitro”, using statistical design (23 factorial designs with three central points). The experiment was carried out, varying the concentrations of citric acid (% w/v, 0; 0.5; 1.0), lime oil (% v/v, 0; 1.0; 2.0) and nisin (IU/mL, 0; 50; 100), using nutrient broth as media. Escherichia coli was inoculated into 11 flasks (106 CFU/mL), which were incubated at 37°C during 24 h. The interaction between lime and lemon oil was also studied. The results showed that after 1h, only citric acid and lime oil had significant effects on inhibition growth of the E. coli as well their interaction (p<0.05). When the factors were combined, the reduction was 100%. No combined effect on combating bacteria growth was observed between lime and lemon oils in the range studied.