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- A modified gompertz model to predict microbial inactivation under time-varying temperature conditionsPublication . Gil, Maria M.; Brandão, Teresa R. S.; Silva, Cristina L.M.Development of effective heat treatments is crucial to achieve food products safety, and predictive microbiology is an excellent tool to design adequate processing conditions. This work focuses on the application of a modified Gompertz model to describe the inactivation behaviour under time-varying temperature conditions at the surface of a food product. Kinetic studies were carried out assuming two different heating regimes, typically used in surface pasteurisation treatments, and compared with isothermal conditions. Parameters were estimated on the basis of generated pseudo-experimental data. It was concluded that the heating period greatly affects microbial inactivation and parameter estimation. If a slow heating treatment is used, the process time should be extended to achieve a given microbial load when compared to a fast heating process. This is explained by the fact that, in the slow heating rate process the temperature was below the lowest temperature for inactivation for a much longer time, in comparison with the fast heating regime. 2005 Elsevier Ltd. All rights reserved.
- Integrated approach on heat transfer and inactivation kinetics of microorganisms on the surface of foods during heat treatments: Software developmentPublication . Gil, Maria M.; Pereira, Pedro M.; Brandão, Teresa R. S.; Silva, Cristina L.M.; Kondjoyan, Alain; Valdramidis, Vassilis P.; Geeraerd, Annemie H.; Impe, Jan F.M. Van; James, SteveThe objective of this work was to create a software application (Bugdeath 1.0) for the simulation of inactivation kinetics of microorganisms on the surface of foods, during dry and wet pasteurisation treatments. The program was developed under the Real Basic 5.2 application, and it is a user-friendly tool. It integrates heat transfer phenomena and microbial inactivation under constant and time-varying temperature conditions. On the basis of the selection of a heating regime of the medium, the program predicts the food surface temperature and the change in microbial load during the process. Input data and simulated values can be visualised in graphics or data tables. Printing, exporting and saving file options are also available. Bugdeath 1.0 includes also a useful database of foods (beef and potato) and related thermal properties, microorganisms (Salmonella and Listeria monocytogenes) and corresponding inactivation kinetic parameters. This software can be coupled to an apparatus developed under the scope of the European Project BUGDEATH (QLRT-2001-01415), which was conceived to provide repeatable surface temperature-time treatments on food samples. The program has also a great potential for research and industrial applications.