Microwave-enhanced sugar beet denaturation was investigated by 1) measuring the temperature response of cossettes due to the thermal effect of microwave power; 2) examining the effect of the microwave dose (MD) on the effective diffusivity of sugar through beet tissues, De; 3) determining the most appropriate MD for microwave denaturation of beets; and 4) dissecting the impact of microwave radiation on the structure of beet cells through transmission electron microscopy. Statistical analysis showed that the temperature response of cossettes contained in a cylinder (diameter 150 mm) and heated at 2 450 MHz was similar to that of distilled water microwaved under the same conditions (a = 0.001). A quadratic response function was found to be a very good approximation to the measured relationship of temperature versus MD (a = 0.01). The effective diffusivity, De, increased rapidly with MD in the range between 216 and 768 kJ/kg. Above this range De remained almost unchanged [(1.63 0.06) 1010 m2/s]. The relationship of De versus MD was closely approximated by a sigmoid-shaped asymptotic function. Beet samples started to lose their stiffness (resilience) from the MD of 1 170 kJ/kg and up due to moisture vaporization. By the criteria of highest possible De and the least possible deterioration of cossette texture, the best MD for microwave denaturation of beets appeared to be within the range from 768 to 1 170 kJ/kg. Considering the disintegration of cell walls caused by microwave radiation at higher MDs, it was better to maintain a MDs of 768 kJ/kg. Electron micrographs showed that microwave power had substantial effects on the structure of beet cells. Similar microstructural changes were observed for beet cells denatured by scalding.