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The combined effects of radiation and sous-vide treatment of chicken breast meat were investigated with respect to survival and growth of Listeria monocytogenes, shelf life, thiamine content, and sensory qualities. Chicken breasts were inoculated with L. monocytogenes 81–861 (105 CFU/g), vacuum-packed, irradiated with electron beam (EB) up to 2.9 kGy, and cooked to an internal temperature of 65.6°C. Sous-vide treatment alone had marginal lethal effect on the L. monocytogenes; the residual inoculum reached 107 CFU/g after 8 weeks at 2°C. However, after the combined treatments of sous-vide and EB at 2.9 kGy, the organism remained undetectable during the 8-week storage period. Parallel studies on uninoculated breast meat revealed that sous-vide samples had a shelf life of less than 6 weeks without EB treatment, whereas samples that were irradiated and then received sous-vide treatment had a shelf life of at least 8 weeks. There was a slight reduction in thiamine levels as a result of the EB treatment, but there was essentially no additional loss of thiamine due to the subsequent sous-vide treatment and storage at 2°C. Electron-beam treatment had very little effect on the odor and flavor of the reheated samples. It was concluded that EB treatment combined with sous-vide treatment can greatly enhance the microbial safety and shelf life of chicken breast meat.

The lack of analytical methods to establish whether or not a food product has been irradiated, and to what dose, if a major obstacle to the wider use of the food irradiation process. o-Tyrosine produced during irradiation of protein-containing foods appears to be a promising marker for this purpose. An HPLC/fluorescence method that allows accurate quantitation of 0.1 ng of o-tyrosine has been developed. The method involves freeze-drying of the sample, acid hydrolysis, solid-phase extraction, fractionation by HPLC, and, in some cases, a second chromatographic separation (HPLC) of the collected fraction. This method was used to determine the radiation dose yield of o-tyrosine in irradiated chicken breast. The results show that there is a linear relationship between the irradiation dose and the yield of o-tyrosine in irradiated chicken meat.

Electron accelerators are being widely-used in industry to process polymeric materials. Their use to cure fiber-reinforced composites is an emerging technology, based on the work done here in Canada, and in France. The advantages of electron curing include ambient temperature curing with reduced internal stress, reduced curing times, and overall cost of savings. In this paper we present a brief review of our work with emphasis on the effects of dose and dose rate, temperature rise during curing, internal stress, voids, properties of matrix resins and a comparison of the properties of electron cured and thermally cured matrices and composites.

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