High-frequency shear and volume viscoelastic moduli of casein particle gel

The mechanism of erythrocyte sedimentation. Part 2: The global collapse of settling erythrocyte network

“…In our opinion, given that the structural organization of colloidal particles affects strongly the attenuation and velocity of ultrasonic waves (e.g. [19][20][21]), the ultrasonic spectroscopy may be used to provide a further insight into the mechanism of erythrocyte sedimentation. This technique can be used without the dilution step, thereby enabling examinations of concentrated colloids such as a whole blood.…”

“…As reported in the literature, the ultrasonic spectroscopy is well suited to study the collapse of particle networks (e.g. [20,21]). …”

The application of ultrasonic spectroscopy to the study of the gelation of milk components

“…Benguigui et al (1994) showed that there was no gel point detected by ultrasonic velocity, but that there was a shoulder on the attenuation/ time plot at about pH 6.1 in milk fermented by lactobacilli, and there was no special contribution of gel formation (determined rheologically) on the attenuation. It should be noted, however, that ultrasonic shear, rather than transverse, waves can be used to measure the vicoelastic moduli of milk gels (Kudryashov, Hunt, Arikainen, & Buckin, 2001;Smyth, Kudryashov, & Buckin, 2001).…”

Real-Time Monitoring of Heat-Induced Aggregation of β-Lactoglobulin in Aqueous Solutions Using High-Resolution Ultrasonic Spectroscopy

“…This produces a decrease of the compressibility of the sample due to the added rigidity of the gel network. The contribution of protein gels to the ultrasonic velocity was analyzed earlier for acid casein gels [38] and rennetinduced gels [39] and it was found that it does not exceed 0.1 m · s −1 at 15 MHz at concentration of proteins close to the concentration of our samples, which is smaller and of opposite sign than the observed changes in the velocity caused by denaturation and aggregation in our samples. Therefore, this contribution could be neglected in further qualitative discussion.…”

“…High-resolution ultrasonic spectrometers provide excellent resolution for both velocity (down to 0.2 mm · s −1 ) and attenuation (down to 0.2 %) [21,22], cover the frequency range from 1 MHz to 20 MHz and allow measurements at elevated pressures and in a broad temperature range (−40 • C to 130 • C) in isothermal and temperature ramp regimes, which cover most processing conditions of protein formulations. The technique has been successfully applied in the ultrasonic analysis of heat-induced coagulation in milks [36,37], monitoring of acid gelation processes [38] and rennet induced gelation in milk [39], and denaturation of whey proteins [27] and other systems. In the present study we have used high-resolution ultrasonic spectroscopy for real-time assessment of structural transformations and aggregation of β-lactoglobulin at different heating rates and pH in the temperature range from 35 • C to 120 • C. The ultrasonic velocity provided information on evolution of the compressibility ("rigidity") of protein globules and protein aggregates and attenuation on the growing size of protein aggregates.…”