Analysis of the Effects of Di-Electric Heating on Common Food Bacterial Pathogens: Evaluation Based on Antibiotic Susceptibility and Infective Doses

In this study, various food samples (n=73) artificially infected by food borne disease pathogens (Escherichia coli, Staphylococcus aureus, Shigella flexneri and Salmonellaenterica spp. paratyphi) were exposed to microwave radiation at different powers (P-00, P-20, P-40, P-60, P-80) and time periods (2 min, 4 min, 6 min, 8 min). The degree of inactivation was estimated by measuring the colony forming units formed in culture before and after exposure of samples to radiation. The data showed that microwave radiation produced a1-2 log reduction when infected food samples were processed. Initial seeded bacterial numbers (>3.0 x 10⁴) were reduced significantly (P<0.05). The most effective power-time combination for bacteria inactivation was 8 minutes at P-80 (1180W) where bacteria numbers were very low (<1.0 x 10³); whereas the least effective power-time combination for bacteria inactivation was 2 minutes at P-20 (295W) where bacteria numbers remained at (>3.0 x 10⁴). The study shows that microwave radiation reduces infective doses of bacteria but does not have any significant effect on their antibiotic susceptibility patterns.