91C-10 |
Electrochemical reactions during ohmic heating |
C. P. SAMARANAYAKE, Food Ag & Bio Engineering, Ohio State Univ., 590 Woody Hayes Dr., Columbus, OH 43210 and S. K. Sastry. Electrochemical reactions, chemical reactions at electrode/solution interface induced by electric current, are of paramount importance in electrochemistry. However, in ohmic heating, the current that passes through the food material is ideally for the purpose of heating, and electrochemical phenomena are highly undesirable. Obviously, the understanding of physico-chemical properties of different electrodes and their electrochemical behavior is important to choose a proper electrode material for processing of a given food product, which in turn contributes to produce safer and high quality ohmically processed foods. We comparatively investigated electrochemical behavior of some electrodes at different pHs under ohmic heating conditions. Four types of electrode materials: stainless steel, titanium, platinized titanium, and graphite were studied for (partial) electrolysis of water and electrode corrosion at pH=3.5, 5.0, and 6.5 using 60 Hz sinusoidal alternating current. The extents of the reactions were measured by head-space H2 gas monitoring and the corrosion analysis by Inductively Coupled Plasma Spectroscopy. H2 evolution was observed with stainless steel and titanium electrodes at all the pHs studied; whereas platinized-titanium and graphite electrodes showed no detectable levels of H2 under the same experimental conditions. Electrode corrosion was observed at all the pHs with all the electrodes. The results suggest that the electrochemical behavior highly depends on the material properties as well as the pH.
Session 91C, Food Engineering: Food process engineering
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