EFFICACY COMPARISON OF FIVE CLEANING SOLUTIONS IN DECONTAMINATION OF ESCHERICHIA COLI IN LETTUCE.

Abstract

Vegetables are healthy additions to human diets nowadays. They are excellent sources of vitamins and minerals that are essential for many functions in the body. However, fresh vegetables are frequently contaminated with foodborne pathogens. Vegetable washing is an important step to help minimize the amount of harmful bacteria prior to consumption.
Efficacy of five washing solutions in reducing Escherichia coli contamination in lettuce was investigated in the present study. Three tested solutions were derived from household ingredients consisting of lime, salt and vinegar. One washing solution was obtained from a local herb, Gotu kola, recently reported to exhibit antimicrobial property. The last washing solution prepared from potassium permanganate, a chemical long used in vegetable cleaning, was also compared.
Lettuce was artificially inoculated with E. coli of about 8 log CFU/g. Following soaking in tested solutions for as long as 30 min, 15% lime solution was shown to be the most effective solution in disrupting E. coli cells achieving a 1.53-log reduction. The rest of the solutions in order of antibacterial effectiveness, 200 ppm potassium permanganate, 10% vinegar, 20% Gotu kola and 1.5% salt, were only able to destroy little amount of E. coli (less than 1 log CFU/g in all treatments). Results provided preliminary data and indicated the feasibility for further improvement of natural ingredient application in vegetable washing.