29F-23 |
Influence of temperature on the disinfectant action of lactic acid on Listeria monocytogenes and Yersinia enterocolitica |
R. VIRTO1, I. Álvarez2, J. Raso-Pueyo1, and S. Condón. (1) Tecnologia de los alimentos, Facultad de Veterinaria. Universidad de Zaragoza, Calle Miguel Servet 177, Zaragoza, 50013, Spain, (2) Tecnología de los Alimentos, Facultad de Veterinaria, Universidad de Zaragoza, C/ Miguel Servet, 177, Zaragoza, 50013, Spain Confirmed outbreaks caused by Listeria monocytogenes and Yersina enterocolitica have been associated with consumption of contaminated foods from plant and animal sources. Organic acids rinses have been proposed for decontamination of the surface of meats and vegetables because, in general, the organic matter had little effect on the bactericidal activity of these acids. The aim of this investigation was to study the effects of temperature and lactic acid concentration to inactivate large populations of L. monocytogenes and Y. enterocolitica for potential application as an antibacterial surface treatment of foods. Both microorganisms were cultivated at 35ºC to stationary phase in tryptic soy broth. . Inactivation experiments were carried out at 4, 20 and 40ºC in distilled water supplemented with lactic acid at 0.5, 1.0, 2.0 and 3.0 % (v/v). Sensitivity of L. monocytogenes and Y. enterocolitca to lactic acid was similar. A treatment of 3% of lactic acid at 20ºC for 15 minutes inactivated the population of both microorganisms around 4 Log cycles. The decrease of treatment temperature from 20 to 4ºC scarcely affected the efficacy of lactic acid. However, at 40ºC the lethality of this acid increased considerably. A treatment of 2% at 40ºC for 2 minutes inactivated the population of both microorganisms more than 5 Log cycles. Inactivation of both microorganisms followed a first order kinetics At all treatment conditions investigated. Lactic acid is an effective agent to inactivate large populations of pathogenic microorganisms at moderate concentrations. The increment of treatment temperature allows reducing either the acid concentration or the treatment time to obtain a given level of microbial inactivation.
Session 29F, Food Microbiology: Control of foodborne microorganisms by antimicrobials
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