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KMID : 1024420110150040398
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Food Engineering Progress
2011 Volume.15 No. 4 p.398 ~ p.403
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Operational Properties and Microbial Inactivation Performance of Dielectric Barrier Discharge Plasma Treatment System
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Mok Chul-Kyoon
Lee Tae-Hoon
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Abstract
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A dielectric barrier discharge plasma (DBDP) treatment system was fabricated and the optimum operating conditions for the plasma generation were determined in order to explore the potential of cold plasma as a non-thermal processing technology. The microbial inactivation performance of the system was also evaluated against Staphylococcus aureus. The system consisted of power supply, transformer, electrode assembly and sample treatment plate. The input power was 220 V single phase AC and amplified to 10.0-50.0 kV on a transformer. A pulsed sine wave of frequency 10.0-50.0 kHz was introduced to the electrode embedded in ceramic as a dielectric barrier material in order to generate plasma at atmospheric pressure. Higher currents and consequently greater power were required for the plasma generation as the frequencies increased. A homogeneous and stable plasma was generated at currents of 1.0-2.0 , and frequencies of 32.0-35.3 kHz. The optimum electrode-gaps for the plasma generation were 1.85 mm without loaded samples. More power was consumed as the electrode-gaps increased. The practically optimum electrode-gap was, however, 2.65 mm when samples were treated on slide-glasses for microbial inactivation. The maximum temperature increase after 10 min treatment was less than 20oC, indicating no microbial inactivation effect by heat and thereby insuring a non-thermal method. The DBDP inactivation effect against Staphylococcus aureus increased linearly with treatment time up to 5 min, but plateaued afterward. More than 5 log reduction was achieved by 10 min treatment at 1.25 A.
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KEYWORD
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plasma, dielectric barrier discharge, optimization, inactivation, Staphylococcus aureus
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