A nondestructive method of determining milk coagulation cut-time was i
nvestigated. Velocity and attenuation of ultrasonic waves through coag
ulating skim milk were measured after rennet addition. The ultrasonic
attenuation measurements were found suitable for distinguishing the ef
fect of different experimental variables (three levels of temperature,
rennet and CaCl2). Based on the rate of change of attenuation during
coagulation, a turning point was defined at which the attenuation rate
change was -0.1 neper/m/min. The cut-time was proposed to be 20 min f
rom the time the turning point was observed. The cut-times predicted b
y this criterion were statistically similar to those predicted by the
manual method currently used in the industry.