Kinetics of Phase Separation of Oat β-Glucan/Whey Protein Isolate Binary Mixtures

The kinetics of phase separation and microstructure
of oat β-glucan/whey protein binary mixtures varying
in concentration (4–16% w/v protein, 0.3–1.2% w/v β-
glucan) and β-glucan molecular weight (1.3×106, 640×
103, 180×103, and 120×103 g/mol) was investigated by
turbidimetry and fluorescent microscopy. The phase separation
of the mixed systems was followed at pH 7.0 and at
room temperature under quiescent conditions. Application
of first principles revealed that phase separation of the
systems follows first-order kinetics. Acceleration of the
phase-separation process was observed with increase of β-
glucan concentration for the three lowest-MW samples but
the highest molecular weight (1.3×106 g/mol) exhibited the
opposite trend. Changes in the polysaccharide molecular
weight resulted in considerable differences in β-glucan
aggregate morphology in the mixed systems. The change in
the continuity of the mixed system from polysaccharide-, to
bi-, to protein-continuous was confirmed for a wide range
of mixed systems differing in biopolymer concentration,
and β-glucan molecular weight