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

Abstract

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 a 1-2 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.