Electrode and pH effects on electrochemical reactions during ohmic heating

Undesirable electrochemical phenomena at electrode|solution interfaces during ohmic heating can be avoided or effectively inhibited by choosing an appropriate electrode material. We attempted to understand the electrochemical behavior of four types of electrode materials: titanium, stainless steel, platinized-titanium, and graphite at pH 3.5, 5.0, and 6.5. The electrodes were examined comparatively using a 60 Hz sinusoidal alternating current. Analyses of surface morphologies of the electrode surfaces, electrode corrosion, hydrogen gas generation, and pH change of the heating media were performed. The results highlight the relatively inert electrochemical behavior of platinized-titanium electrodes at all the pH values. A pilot scale study at 39.8 kW further demonstrates the potential use of platinized-titanium electrodes for ohmic heating of foods with commonly available low-frequency alternating currents.