17H-26 |
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C. P. SAMARANAYAKE1, S. K. Sastry1, and Q. H. Zhang. (1) Dept. of Food, Agricultural & Biological Engineering, Ohio State Univ., 590 Woody Hayes Dr., 260 Agricultural Engineering Bldg., Columbus, OH 43210-1058 Electrochemical reactions are undesirable during ohmic heating, and commercially viable methods that minimize them are of great interest. We examined a pulsed ohmic heating technique to determine its effects on electrochemical reactions. Effects of pulse parameters, such as frequency, pulse width, and delay time (off-time between adjacent pulses) were studied, in comparison with conventional 60 Hz (sine wave) ohmic heating using stainless steel electrodes. Electrode corrosion was measured by inductively coupled plasma-mass spectrometry (ICP-MS). Hydrogen gas accumulation in the headspace of the ohmic heater, and pH change of the heating medium were also measured. The results indicate that the pulsed ohmic heating technique is capable of significantly minimizing the electrochemical reactions, in comparison to conventional 60 Hz ohmic heating. Pulsed ohmic heating operated at higher frequencies and shorter pulse widths yielded the lowest rates of electrochemical reactions. The delay time was found to be a critical factor.
Session 17H, Food Engineering: Thermal processes
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