Suspension stability and size distribution of particles in reconstituted, commercial calcium caseinates

Four commercial calcium caseinates were reconstituted in water and various properties of the particles or aggregates were determined. Particle size di stribution was determined with a Malvern Mastersizer. All the dispersions e xhibited bimodal particle size distributions with modes at about 0.4 and 10 mum. The particle size distributions changed quite rapidly for the first 2 h after reconstitution and then changed more slowly for up to 6 h. The mode of the first peak did not change significantly during this time, but the m ode of the second peak decreased. It appeared that the larger particles wer e either dissociating into smaller particles or dissolving with time. The s ample with the lowest suspension stability had the largest particles. Sedim ent formed by centrifuging the dispersions at 700 y had a moisture content of about 77% and was slightly enriched in ash compared to the original disp ersion. The density of the hydrated sediment was calculated From the sedime nt composition to be about 1073 kg m (- 3). This appears to be much higher than the density of the sedimenting particles as estimated from Stokes law. (C) 2001 Published by Elsevier Science Ltd.