Volumetric heating methods, such as ohmic and microwave heating, have been shown to be beneficial in terms of saving time and energy. However, understanding their effects on bioactive components of the processed food is also required for their commercial application. In this regard, the effect of ohmic (at low and high power intensity) and microwave heating on some nutritional aspects, such as antioxidant activity, iron, vitamin C, and phenolic content, of kohlrabi, turnip, potato, and radish were assessed and results were compared to that of conventional cooking. Ohmic heating saved up to 92 and 88% of the cooking time as compared to conventional and microwave cooking, respectively. Due to shortening the process time, a better antioxidant activity, higher Iron, ascorbic acid, and phenolic content were observed in ohmic treated samples which could be related to the shorter process time. Moreover, increasing the power intensity of ohmic heating shortened the cooking time and enhanced the concentration of bioactive compounds. In addition, electrochemical reactions involved in ohmic heating did not negatively affect the studied parameters of the cooked vegetables. The High-intensity ohmic cooking could be proposed for commercial production after further studies on the safety aspect of this technique.