Ultrasonic velocity measurements of backscattered acoustic waves for monitoring the enzymatic coagulation of milk

Abstract

In this work, the milk coagulation process was monitored by a nondestructive ultrasonic technique. Three analysis methods were used to calculate ultrasonic wave velocity and assess their effectiveness in tracking the physicochemical changes: Cross-correlation, Spectrum Ratio, and Smoothed Pseudo-Wigner-Ville Transform. The obtained results show a consistency between the velocity measurements made by these three methods, with a steady increase observed during coagulation and both phases are visible. The time-frequency method was most effective, showing a clearer transition between the two phases. This study suggests that non-destructive ultrasonic techniques with time-frequency analysis could be advantageous for monitoring of milk coagulation and ensuring dairy product quality.