The particle size distribution can be calculated based on several
models: most often as a number or volume/mass distribution. A
volume distribution is skewed more towards the larger droplets,
whereas a number distribution is skewed more towards the smaller
droplets (McClements, 2004). In our system some of the particles
are large (gum tragacanth) and if we consider the diameter on the
volume basis we will miss the data for the smaller particles so we
decided to calculate the diameters on the surface and number basis.