Rice cooking using ohmic heating: Determination of electrical conductivity, water diffusion and cooking energy

Abstract

In this research, ohmic heating was proposed as an alternative method to cook rice. Jasmine rice grain's swelling behavior and electrical conductivity, water diffusion, and cooking energy were investigated. Results showed that rice grains expanded faster when the temperature was higher than 80 °C. A tri-phased linear relationship between electrical conductivity and temperature was observed with two transition temperatures at around 60 and 80 °C. Water diffused into rice grains faster when the temperature was higher than 80 °C and even faster during steeping in boiling water. A higher electric field strength increased the diffusion rate. The energy consumption by the ohmic cooking process was about 1/4 of the total energy consumed by an electric rice cooker while the cooking time was slightly shorter (18 and 17 min). Differences from a rice cooker included no fouling was observed of the rice-layer on the cooking container after ohmic cooking.