Effect of Different Frequency, Voltage, and Electrical Fields on The Pasteurization of Arenga Sap (Arenga pinnata) Using Ohmic Heating

The preservation of palm sap is challenging due to its complex nutritional content, specifically at room temperature. One effective preservation method is pasteurization using ohmic heating which extends shelf life, without compromising the nutritional content. Therefore, this study aimed to investigate changes in the chemical characteristics of pasteurized Arenga sap when subjected to various frequencies and voltages to generate a certain power. Ohmic heating was performed at a controlled temperature of 65 ℃ with variable frequencies of 250 Hz, 150 Hz, and 50 Hz as well as certain voltages to produce 120 watts, 80 watts, and 40 watts of power. The total phenol, antioxidant activity, and reducing sugar were measured based on the duration of the pasteurization process. To assess the significance of the results, a randomized block design with ANOVA and the LSD monitoring test were used. The results showed that the longer the pasteurization process, the lower the total phenol content and antioxidant activity, while the reducing sugars formed increased. RBD indicated that phenolic content and reducing sugar were significantly affected by frequency and voltage to produce electric power of 120 watts and 80 watts. However, for reducing sugar, both frequency and voltage as well as their interaction had no significant effect. The best results were obtained at a frequency of 250 Hz with a voltage of 46 volts to produce 120 watts of power with a total phenol reaching 16.46 GAE/g, antioxidant activity of 91.5 (mg/mL), and 15.7% reducing sugar with a pasteurization time of 110 minutes.