An ultrasonic system has been developed to employ a pulse-transmission
method of measurement during coagulation of rennetted milk. The ultra
sonic waves were transmitted through the milk and the coagulation proc
ess was followed after adding the enzyme. The observed changes in ultr
asonic attenuation during coagulation were used to predict the coagula
tion 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 ther
e was no significant difference (at 95% level) between the coagulation
times determined by both methods. Thus, the ultrasonic method has pot
ential for nondestructively estimating the coagulation time of rennett
ed milk. Determination of coagulation time is useful in evaluating the
effectiveness of different enzymes under varying conditions.