Suitable Voltage Determination of Ohmic Heating Process for Household Pork Steak Preparation Machine

Abstract

This paper presents the procedure to determine the suitable applied voltage in the ohmic heating process for pork steak preparation combined with conventional grilling. The electrical, physical, and chemical properties parameters that are investigated. During the ohmic heating process, not only the temperature rises and duration time for each cooking level examined, but also the ampacity required of the equipment in the process is considered. In the experiment, meat samples with cross-section areas: 42, 43, and 44 inch² with a thickness of 0.5 inches were tested by an alternating current (AC) voltage source: 20, 25, and 30 V at a frequency of 50 Hz within 300 seconds. The criteria for selecting the suitable voltage were the rate of temperature rise of the meat sample must increase linearly for all 3 sizes of meat before the pre-boiling temperature, the maximum load current did not exceed the copper wire ampacity, and the duration time used between each adjacent stage of meat cooking was chosen to be longer. From the experiment results, the appropriate voltage for the steak cooker's default setting was 20 V for the following reasons: 1) The rates of temperature increase were linearly proportional for all 3 sizes of meat samples as well-done or internal meat temperature reached 71 ^oC and within 300 seconds. 2) The maximum load current of the applied voltages at AC 20 V was the lowest current (7.43 A). 3) The duration time used between each adjacent stage of meat cooking of AC 20 V was the longest time compared to others. Thus, the steak’s cooking level can be easily managed. After the ohmic heating process, the steaks' physicochemical properties (pH, moisture, drip loss, cooking loss, water holding capacity (WHC), shear force, and color) were evaluated. The steaks did not approach the dangerous toxicity level, and the cooking time was nearly half that of conventional grilling.