and non-homogenized systems (Fig. 8a). In general, the lightness of a
colloidal dispersion depends on particle concentration, size, and refractive
index contrast (McClements, 2002). The lower lightness observed
at the pH extremes used in this work may therefore have been due to
changes in size, structure, concentration and/or refractive indices of
protein particles in different systems.
Photographs of the samples showed that non-homogenized MWP
suspensions were highly prone to sedimentation across the entire pH
range exhibiting a thick layer of white sediment at the bottom of
the tubes (Fig. 8a inset), which can be attributed to their large particle
dimensions. Conversely, no sedimentation was observed in the homogenized
MWP suspensions across the entire pH range studied with all
samples having fairly similar milky appearances. The increased sedimentation
stability of these systems is due to the relatively small size
of the protein particles. A major advantage of using homogenized
MWP suspensions may therefore be to improve their stability to gravitational
separation.