The particle size distribution of the samples was determined by
laser diffraction using a Cilas 1090 particle size analyser (Orleans,
France) equipped with a 5mW He/Ne (635 nm) laser beam. The
sample was added to the measuring unit containing distilled water
at a pH similar to the pH of the sample.
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.
The particle size measurements are reported as D0.1 mm,
D0.5 mmand D0.9 mmon a surface and number basis that is the size
of the particle below which 10%, 50%, and 90%, respectively, of the
sample particles lie.
The diameter on the surface is also known as the diameter D[2,
1] mm was automatically calculated using software provided with
apparatus. Its mathematical formula is as follows: