Mechanical evolution of tofu curd in gelation was investigated using low-power ultrasound and textural analysis. Two independent ultrasonic parameters, velocity and attenuation, were measured at the frequency 1 MHz as a function of time after addition Of the calcium sulphate (CaSO4 center dot 2H(2)O) coagulant to heated soya milk. The responsive ultrasonic Velocity has a plateau in the beginning of gelation and tends to a lower steady state after the formation of tofu gels. Ultrasonic attenuation exhibits first-order kinetics that matches the development of firmness revealed by textural analysis. Low-power ultrasound explores the formation of tofu gels ill the aspects of pre-gelation processes, protein aggregation in gelation, and mechanical evolution in the gel at the post-gelation stage. (C) 2009 Elsevier Ltd. All rights reserved.