Greener Journal of Biological Sciences

Open Access

Greener Journal of  Biological Sciences Vol. 3 (6), pp. 220-228, August 2013.

 © 2011 Greener Journals

Research Paper

Manuscript Number: 070813706


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


Maureen Khatiera Luvanda1*, John Maingi2,

Paul Okemo3, Yang E.4


1Department of Medical Laboratory Science, Kenyatta University, Nairobi, Republic of Kenya. P. O. Box 8528-00300, Nairobi, Kenya.

2,3Department of Plant and Microbial Sciences, Kenyatta University, Nairobi, Republic of Kenya.P.O. Box 43844 (00100).

4Department of Microbiology, Xi’an Jiaotong University, Xi’an, People’s Republic of China.

 2Email: maingijohn @ gmail. com, Tel. +254-020-8710901 ext 57177, Fax +254-8711575

3Email: paulokemo @ gmail. com, Tel: +254722942072

4Email: eyang @ mail.xjtu. edu. cn, Tel: +8615029979505


*Corresponding Author’s Email: maureenluvanda @ gmail. com, Tel: +254703590667


In this study, various food samples (n=73) artificially infected by food borne disease pathogens (Escherichia coli, Staphylococcus aureusShigella 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.

Keywords: Di-electric Heating, Colony Forming Units, Inactivation, Multi-drug resistance, 

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