Abstract

GOMEZ ALVAREZ, L. M; JAIMES SUAREZ, S  and  MONTES ALVAREZ, J. Evaluation of a product based on organic acids before E. coli and Salmonella spp, in the disinfection of fresh lettuce. Rev. Lasallista Investig. [online]. 2012, vol.9, n.2, pp.122-131. ISSN 1794-4449.

Introduction. Fresh fruits and vegetables are an essential component of many people's diet worldwide and their consumption is increasing, due to several factors such as the tendency towards healthier food consumption. Organic acids appear as an alternative to replace chloride in the disinfection of these products, given their good antimicrobial performance and their condition as GRAS (Generally Recognized as Safe). Objective. Determining the E. coli and Salmonella spp's reduction in Batavia lettuce (Lactuca sativa), by the use of a product based on organic acids. Materials and methods. Lettuce samples were inoculated with known concentrations ofSalmonella enteritidis ATCC 13076 and Salmonella typhimurium ATCC 14028 and E. coli ATCC 8739 y ATCC 25922, which were put before solutions of the product (organic acid) at 1000, 1200 and 2000 ppm during three exposition periods. They were later neutralized with a Letheen broth solution and analyzed by means of on plate accounts. Contaminated samples of not disinfected lettuce were taken as positive controls. The effectiveness of the disinfection was evaluated by analyzing the logarithmic reduction of the microbial population during the time of exposition to the disinfectant, in different concentrations of the active principle. Results. Reductions above 99% were obtained for the lettuce samples inoculated with E. coli Salmonella spp. In the lettuces inoculated with E. coli, the reduction of the population reached 2.09 ± 0.14 Log UFC/g, while the reduction of Salmonella spp was 0.98 ± 0.19 Log UFC/g. The study revealed that the most effective treatment under antimicrobial terms before high populations (105 UFC/g) of the pathogens inoculated was that with a 2000 ppm concentration and a 5 minutes contact time. Conclusion. The in vitro and the inoculation tests demonstrated that E. coli is more sensitive to the disinfection treatment than Salmonella spp. The disinfectant based on organic acids is an effective and safe alternative to reduce pathogen microorganisms in vegetables, reducing the microbiological hazard associated to such products, which are usually eaten raw.

Keywords : Organic acids; Salmonella spp; Escherichia coli; disinfection; lettuce.

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