Development of a Microwave Treatment Technique for Bacterial Decontamination of Raw Meat

Abstract

The present study developed and verified a 'cold' microwave (MW) treatment that could lead to the inactivation of two common pathogenic species of bacteria, Escherichia coli and Staphylococcus aureus, in raw meats. A number of experimental conditions were designed and tested to maximise MW exposure without overheating the samples. The non-thermal effect was maximised by multiple exposure to attain efficient MW threshold intensities. It was shown that at sub-lethal temperatures repeated exposure using high frequency MW radiation was significantly more effective in decontaminating bacteria in raw meats compared to a single exposure. It was concluded that non thermal inactivation of pathogenic bacteria in raw meats could be achieved at defined conditions using high frequency MW radiation.

A New Sterilization Technique of Bovine Pericardial Biomaterial Using Microwave Radiation

“…A cavity characterization option was also available that allowed evaluation of the performance of a material in the cavity to assist in determining the optimum processing conditions as described in our previous design. 25 …”

“…Previous studies indicated that during microwave sterilization of bacteria performed at 508C, around 30% reduction in bacterial numbers was achieved as a result of the heating effect alone and not radiation. 25 Therefore, for the threshold treatment temperature, 458C was preferred, as it is the temperature at which the target pathogens were determined to be unaffected by heat. The experiments were prepared using the highest available frequency (lowest wavelength) of 18 GHz.…”

“…To ensure uniformity of exposure, each sample was placed on a Teflon pedestal in the same position, which had been determined by electric field modeling using CST Microwave Studio 3D electromagnetic simulation software. 25 This analysis allowed for the microwave power distribution at that particular position to be uniform, thereby eliminating hot spot effects. 17 Further, because the wavelength of microwaves in the cavity was much greater than the dimensions of the sample (10Â10Â0.5 mm), the possibility of noneven heating due to a nonuniform field distribution was negligible.…”

“…Our previous study 25 showed that when using MW settings of 18 GHz and 16 W, three repeated exposures (with cooling in between exposures) allowed for the nonthermal effects of the MW radiation to be considerably manifested, leading to a significantly higher bacterial mortality rate than that obtained when using a single exposure. Therefore, the same methodology was adopted in the present study, and samples were exposed to three repeated exposures to MW radiation.…”

“…The first stage of the study aimed at examining the mechanical properties (viscoelastic properties and tensile strength) and thermal degradation (thermogravimetric analysis and differential scanning calorimetry) of bovine pericardial biomaterial after the MW sterilization process. The second stage was designed to use previously optimized microwave parameters 25 to identify the point at which optimum bacterial inactivation could be achieved without compromising the structure and functionality of the bovine pericardial biomaterial.…”