Milk Coagulation Cut‐time Determination Using Ultrasonics

Abstract

A nondestructive method of determining milk coagulation cut-time was investigated. Velocity and attenuation of ultrasonic waves through coagulating skim milk were measured afrer rennet addition. The ultrasonic attenuation measurements were found suitable for distinguishing the effect of different experimental variables (three levels of temperature, rennet and CaClJ. 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 from the time the turning point was observed. The cut-times predicted by this criterion were statistically similar to those predicted by the manual method currently used in the industry.

Estimation of clotting and cutting times in sheep cheese manufacture using NIR light backscatter

“…However, cutting the curd too late results in poor quality because the curd is too firm at cutting and syneresis is inhibited, which results in a high-moisture cheese. As there are numerous factors that influence the gel formation and have an effect on the cutting time, cutting the coagulum at a pre-determined time is questionable even if that is the way it is done in many cheese plants (Gunasekaran and Ay 1996). On the other hand, cutting the curd based on empirical inspection of the gel by the operator is only acceptable if the evaluation is made properly (Hori 1985).…”

An Efficient Ultrasonic Method to Control the Coagulation Enzymatic of Milk

“…The latter, as it was used by [24] consists of using the second derivative of the phase velocity and consider the extreme of this second derivative as the transition point which marks the end of the enzymatic phase of coagulation. This transition point has been identified as clotting time [23].…”

“…However, most of these methods have a destructive character that their direct contact with the coagulum causes the deformation of the gel what limits the quality of the final product. To find more effective ways having a non-destructive nature, then the use of ultrasound proves interesting [21][22][23][24][25][26][27][28]. Because of their ease of placing in-situ and their non destructive properties, the techniques of ultrasonic wave propagation seem particularly well suited to monitor the gelation of the milk.…”

Measurement of the rennet clotting time of milk by digital image sequences (2D+t) processing

“…In an aqueous solution, shear wave is damped, so only longitudinal wave can be used. Gunasekaran and Ay (1996) experimented with ultrasounds to determine coagulum cutting time. Nassar et al (2001) used low-frequency ultrasonic technique to monitor milk coagulation.…”