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Modelling and Simulation of Microwave Field and bacteria Interactions

Project manager: Professor Elias Siores

Tel ext 01204 903501

There are several factors that influence the effect of microwaves on microorganisms in foods, like the intrinsic characteristics. These include pH moisture level, oxidation-reduction potential, nutrient content, antimicrobial constituents, biological structures, chemical composition of the shape and size of the bacteria carrying load. There are also the influential extrinsic characteristics – temperature, humidity and gases of the environment, frequency and intensity of the radiation, length of time of exposure, position in the effective field and other factors. Other important factors include the physical and the chemical composition of the microorganisms being irradiated and their stage of existence (moist or wet, spore, etc) and numbers present. It is envisaged microwave radiation can destruct several microorganisms including E. Coli, Salmonella, L. monocytogenes, S. aureus. This is probably due to the thermal effect induced by the microwaves. The bacteria absorb electromagnetic radiation due to the difference in their dielectric properties from the medium/carrier. The factors that affect the reduction of bacteria are: frequency, power output level, time and pulsed power.

In this paper the interaction of microwaves with microorganisms is investigated. The different factors that affect this interaction are examined and the different simulation techniques describing the interaction phenomena will be developed. The different geometries of cells are taken into consideration and the assumptions are made in order to describe the dependence of their relaxation spectra on frequency. The research and development work also includes experimental results and modelling of the microwave sterilisation process using different frequencies and different microbial samples. The different modelling techniques for simulating interactions will be described and specific methods detailed. 2-D and 3-D computational efforts will be developed.

Academic department the project sits within: CMRI

Funder(s): EU FP6 Marie Curie