SOME ASPECTS OF MEASURING THE SIZE AND RATE OF DISPERSION OF MILK POWDER AGGLOMERATES USING THE MALVERN-PARTICLE-SIZER-2600C

The Malvern Particle Sizer, which applies Fraunhofer light diffraction theory, has recently become popular for measuring particle size distr ibutions in dried milk and other powders. The size distribution is obt ained by dispersing the powder in air or a suitable liquid in the lase r light beam of the instrument. The suitability of the dry powder disp ersion system (DPD system) of the Malvern Particle Sizer 2600c for cha racterizing agglomerated milk powders was examined. It was found that, although the instrument gave reproducible and reliable results for no n-agglomerated powders (standard milk powders), milk powder agglomerat es could be broken in the standard DPD system and erroneous size distr ibutions might be obtained. However. the DPD system had potential for providing an objective test of the mechanical stability of milk powder agglomerates. In addition, the transient size distribution during dis persion of an instantized agglomerated milk powder in water was measur ed at intervals of about 20 s.