29G-8 |
Kinetics of inactivation of L. monocytogenes by chlorine |
R. VIRTO1, I. Álvarez2, S. Condón, and J. RASO-PUEYO1. (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 Exposure to chlorine is an effective means to reduce the microbial population and this agent is used extensively in food industry as a method of disinfection of foods surfaces and equipment. In contrast to other chemical agent, the concentration of chlorine declines during the treatment. Antibacterial activity of chlorine on Listeria. monocytogenes has been investigated. However the relationship between the kinetics of inactivation and the decline of the available chlorine concentration is unclear. The objective of this investigation was to describe the kinetics of inactivation of L. monocytogenes by different concentrations of chlorine and to correlate this kinetics with the decline of available chlorine during the treatment. Effectiveness of chlorine solutions of 6, 8, 10, 15, 20 and 30 ppm (w/v) against L. monocytogenes was investigated. Survival curves were described by a mathematical model based on a Weibull distribution. A treatment of 30 ppm for 30 seconds inactivated 1, 2 and more than 5 Log cycles when the initial microbial concentration was 2x108, 1x108, and 5x107 UFC/ml respectively. At the beginning of treatment, the available chlorine concentration decreased rapidly to a certain level and then continued decreasing slowly. This decline was much faster than the decrease of the microbial population. Survival curves at the different chlorine concentrations investigated were concave upwards. A linear correlation was observed between the Log of the scale factor of the Weibull model and the initial chlorine concentration Efficacy of chlorine depended significantly on the microbial concentration. A model based on the Weibull distribution accurately described the concave upward survival curves observed. The decline of the concentration of available chlorine during the treatment was not correlated with the shape of the survival curves.
Session 29G, Food Microbiology: General
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