Use of shear wave elastography for monitoring enzymatic milk coagulation

• We have followed in real time milk coagulation processes.
• Mechanical properties were measured by ultrasound shear wave elastography without interfering with the coagulation process.
• We identify the coagulation time as well as the mechanical properties which can be related to the cutting time.
• We were able to estimate elastic properties of the curd during the coagulation process in two dimensional maps every minute.

In the manufacturing of cheese, the cutting of the curd is an essential step which depends on the firmness of the curds and significantly affects the yield of the cheese and its quality. In this work, we present a technique to measure elastic properties of the curd during coagulation that could be used to quantitatively determine the cutting time. The technique uses ultrasound to generate and measure shear waves. These waves do not propagate in liquids and their velocity of propagation depends on the viscoelastic characteristics of the medium. Hence, they can be used to identify the beginning of coagulation and subsequently to monitor the evolution of the coagulum firmness. Our results showed this technique is sensitive to changes of the medium structure during coagulation. It also proved reproducible and sensitive to different coagulation conditions. Therefore this technique can be used to develop a system suitable for the dairy industry.