Effect of ultrasound treatment on particle size and molecular weight of whey proteins
Journal of Food Engineering Volume 121, January 2014, Pages 15–23 Anet Režek Jambrak
After treatment with an ultrasonic probe, ultrasound caused a decrease in particle size.
The distribution of size of whey proteins were narrowed.
The specific free surface of whey proteins were increased.
Ultrasonic bath treatment showed changes in molecular weight of protein fractions.
The aim of this study was to observe the effect of ultrasound on particle size and molecular weight of whey proteins. In this work high-intensity ultrasound (20 kHz probe and 40 kHz bath) were used. 10 wt.% protein model suspensions of whey protein isolate (WPI) and whey protein concentrate (WPC-60) were treated with ultrasound probe (20 kHz for 15 and 30 min) and ultrasound bath (40 kHz for 15 and 30 min). The results of particle size distribution have shown that, after treatment with an ultrasonic probe of 20 kHz, ultrasound caused a decrease in particle size, narrowed their distribution, and significantly increased the specific free surface in all samples. After treatment with ultrasonic bath of 40 kHz, there was a significant reduction in the size of particles. After treatment with probe of 20 kHz there was a significant decrease in molecular weight and protein fractionation. Ultrasonic bath treatment with 40 kHz ultrasound also showed significant changes in the composition of the molecular weight of protein fractions. Prolonged treatment of WPI with ultrasonic bath of 40 kHz encourages the formation of aggregates of molecules.
Effect of Power Ultrasound Pre-treatment on the Physical and Functional Properties of Reconstituted Milk Protein Concentrate
Sun Yanjun Journal of Food Engineering Available online 18 September 2013
The ultrafiltered milk retentates were treated with PUSprior to spray drying.
We examine physical and functional properties changes of MPC for PUS pre-treatment.
The pH and conductivity of MPC reconstitution did not change significantly.
The functionality of MPC such as solubility increased for PUS pre-treatment.
This work investigated the impact of power ultrasound (PUS) pretreatment on the physical and functional properties of reconstituted milk protein concentrate (MPC) 80. Ultrafiltered/diafiltered (UF/DF) milk protein retentates were treated with PUS (12.50 ± 0.31 W and 50% amplitude) for 0.5, 1, 2, and 5 min prior to spray drying.
Results revealed that the particle size (D50) reduced from 28.45 μm to 0.13 μm after 0.5 min of sonication. Solubility increased significantly from 35.78% to 88.30% after 5 min of PUS pre-treatment. Moreover, the emulsifying activity index (EAI) of MPC samples increased significantly as the time of ultrasonic treatment was prolonged. Additionally, the emulsion stability index (ESI) initially increased after ultrasound treatment for 1 min. Surface hydrophobicity was greatly increased with more hydrophobic groups exposed to the environment. PUS pre-treatment also promoted an increase in the storage modulus (G′) of the MPC solutions. Viscosity significantly decreased after PUS pre-treatment. This result was confirmed by the microstructure of the powder, with small particles formed and trapped in dents of large particles. However, sodium-dodecyl sulfate–polyacrylamide gel electrophoresis showed no significant change in protein molecular weight.
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