COMPARING THE BACTERICIDAL EFFECT OF SOLUTIONS OF CHLORINE AND ORGANIC ACIDS FOR REDUCING Escherichia coli AND Enterococcus faecalis IN FOOD

Chlorinated water is widely used for the disinfection of fruits and vegetables; however, the organic matter present in food could inactivate chlorinated compounds and reduce its efficiency. The substitution of chlorinated compounds by organic acids (mainly produced by fermentation) offers an alternative, both for reducing the negative environmental effect and for not be harmful to human health. The aim of this study was to evaluate the use of acetic acid and lactic acid as alternative to minimize the use of chlorine for food disinfection. Bactericidal activity of different solutions of lactic acid (LA), acetic acid (AA), apple cider vinegar and chlorine against Escherichia coli and Enterococcus faecalis was determinate according to Association of Official Analytical Chemists (AOAC 965.13) that is recommended by the Brazilian legislation for development of disinfectants for vegetables. The bactericidal efficiency of these solutions was also evaluated for disinfection of tomato, lettuce, parsley and cucumber samples artificially contaminated with these bacteria suspensions (7 log CFU/mL). Seven different solutions of organic acids, namely A (LA 15 g/L), B (glacial AA 15 g/L), C ( glacial AA 15 g/L + LA 10 g/L), D (glacial AA 15 g/L + LA 15 g/L), E (vinegar, acidity 15 g/L), F (vinegar, acidity 1.5 g/L + LA 1.0 g/L) and G (vinegar, acidity 15 g/L + LA 15 g/L), and a chlorine solution namely H (0.2 g/L sodium hypochlorite solution) were evaluated. According to AOAC methodology, solutions C and F eliminated E. coli after 5 and 2 min, respectively, but none of solutions of organic acids eliminated E. faecalis, even after 15 min of exposure. On the other hand, the solution H (chlorine) eliminated both bacteria in less than 1 minute. However, when chlorine was tested with artificially contaminated vegetables, it had lower efficiency than organic acids, possibly due to the presence of organic matter that reduces its efficiency. The solutions C and F presented the best results in the food disinfection procedure, because reduced E. coli and E. faecalis counts, on average, 4 and 2 log CFU/g, respectively. The results indicated that it is possible replace the chlorine for organic acid solutions in the food disinfection procedures.