In situ inhibition of Escherichia coli isolated from fresh pork sausage by organic acids

Abstract

The main aim of this study was to evaluate the inhibitory effect of different concentrations of organics acids citric, lactic, acetic, and propionic on E. coli isolated from pork sausage. Two experiments were performed in vitro, respectively: agar disc diffusion and minimum inhibitory concentration (MIC) determination. In agar disc diffusion, the minimum concentration of 1.29 M of citric acid inhibits bacterial growth. There was no statistically significant difference in the MIC of citric and lactic acids; citric and lactic acids were more effective than acetic and propionic acids. Based on in vitro results, lactic and citric acids were added to pork sausages with E. coli. The addition of citric acid caused a significant reduction (P < 0.01) in the pH of the sausages. Citric acid was most effective 15 d after inoculation; E. coli counts were reduced by 4.53 log units compared with time 0. Due to late inhibitory action of citric acid in the study, its effect may be more effective over E. coli in sausage that requiring longer storage, such as fermented sausages.