Ultrasonic Attenuation Measurements for Estimating Milk Coagulation Time

An ultrasonic system has been developed to employ a pulse-transmission method of measurement during coagulation of rennetted milk. The ultrasonic waves were transmitted through the milk and the coagulation process was followed after adding the enzyme. The observed changes in ultrasonic attenuation during coagulation were used to predict the coagulation time indicating the onset of coagulation. Coagulation times were also determined by measuring the apparent viscosity of the coagulum as suggested in the literature. Statistical analysis indicated that there was no significant difference (at 95% level) between the coagulation times determined by both methods. Thus, the ultrasonic method has potential for nondestructively estimating the coagulation time of rennetted milk. Determination of coagulation time is useful in evaluating the effectiveness of different enzymes under varying conditions.