Estudio del Comportamiento Cinético de Microorganismos de Interés en Seguridad Alimentaria con Modelos Matemáticos
PALABRAS CLAVE: Parámetros cinéticos, modelos predictivos, turbidimetría.
Predictive microbiology combines both the knowledge about the response of microorganisms to several environmental conditions and the mathematical modelling to make growth predictions.
The conventional food microbiological tests have several limitations, such as the time needed for the enrichment and the culture of samples. Taking into account the need of (i) studying faster methods to monitor the bacterial growth and (ii) applying measures to prevent outbreaks of foodborne diseases, the aim of this study is to apply the turbidimetric technique to monitor the growth of microorganisms with interest in food safety.
With the obtained turbidimetric data, kinetic parameters were calculated and compared with the optical density curves for 24 h in BHI broth of Escherichia coli, Listeria monocytogenes, Salmonella typhimurium and Staphylococcus aureus. Lag times, generation times, and growth rates were calculated within the lineal section of the optical density curves. Three mathematical models were obtained and compared for calculating the kinetic parameters of each microorganism.
The kinetic behaviour of these microorganisms was analyzed taking into account the pathogenicity and no pathogenicity of Escherichia coli. Moreover, kinetic results of Gram-positive microorganisms and Gram-negative microorganisms were compared.
The individual behavior of each microorganism has been different in the 96 combinations of temperature, pH and NaCl. However, all of them reduced their growth rate, and increased their lag and generation times when the percentage of NaCl and the pH values were also increased. Temperature, pH and NaCl can affect in different ways the response surface models to predict the kinetic parameters. The pH was the parameter with more influence on the kinetic behaviour of all microorganisms studied.
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Advisor:Mora Ventura, Maria Teresa; Quinto Fernández, Emiliano José
School:Universitat Autónoma de Barcelona
Source Type:Master's Thesis
Keywords:458 departament de ciències animals i dels aliments
Date of Publication:12/17/2007