Ultrasonic measurement of milk coagulation time

Abstract

Using a pulse reflection technique an ultrasonic system has been developed to monitor in situ the coagulation process of rennetted milk. The velocity and attenuation of ultrasonic waves through coagulating milk were continuously monitored. The observed changes in ultrasonic velocity during coagulation were used to predict the coagulation time. The coagulation time is indicative of the transition from the enzymatic phase to the physicochemical phase. The determination of coagulation time has a decisive role in determining the qualities of the end product in cheesemaking.

Evaluation of the performance of Frying Oils using an ultrasonic technique

“…To obtain the phase ϕ experimentally, the FFT of signals A2 and A4 were calculated (Bakkali et al, 2001).…”

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.…”

“…However, this technique has not been used to determine the clotting time. Another method, our research group, [24] use an ultrasonic pulse technique by reflection for determining the clotting time from the phase velocity changing by calculating the second derivative of the polynomial function obtained by smoothing the experimental curve of the phase velocity.…”

Dispersion of Colloidal Suspensions and Their Stability

“…For instance, dielectric spectroscopy was used to investigate the moisture uptake and stability of cosmetic creams (Sutananta et al 1996;Tamburic et al 1996), and acoustic parameters (resonance frequency, attenuation, sound speed) were shown to correlate with sol-gel transition in suspensions of colloidal silica (Senouci et al 2001), as well as with the phase transition of renneted milk (Bakkali et al 2001). …”