10-5 |
Salmonella enteritidis risk assessment: A kinetic analysis |
S. F. ALMONACID, J. Gutierrez, and R. Simpson. Departamento de Procesos Químicos, Biotecnológicos y Ambientales, Universidad Técnica Federico Santa María, Avenida España 1680, Valparaíso, Chile Egg and egg preparations are important vehicles for Salmonella Enteritidis (SE) infections. The influence of time-temperature becomes important when the presence of this organism is found in commercial shell eggs and considering that refrigeration is not mandatory in Chile. The objective of this study was to develop and validate a computer aid mathematical tool to estimate temperature at different egg locations under variable ambient temperatures. A Finite Difference scheme was used to solve the heat transfer model. The Finite Difference scheme was implemented in C++, taken into account the shape and complex nature of egg system. Parameters of interest; local (h) and global (U) heat transfer coefficients, were estimated by an inverse procedure from experimental data. Good agreement was found between experimental and theoretical data, mean temperature errors were between 0.19 and 0.32°C. The validated model was combined with a kinetic model taken from literature to estimate vitelline membrane breakdown and average SE growth in yolk and membrane surface. It was estimated that egg should be kept at temperatures of 15°C or lees when vitelline breakdown is taken as critical target, considering egg quality shelf-life as 30 days. The developed model will have practical applications, mainly in summer season when temperatures becomes a critical problem for egg transportation and storage.
Session 10, International: Division Lecture and Paper Competition
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