Physiochemical characterization of β-glucan and in vitro release of lactoferrin from β-glucan microparticles

The average molecular mass of β-glucan was 241,700 g/mol with a polydispersity of 1.433. At lower concentrations, gels showed Newtonian flow behaviour and shear thinning properties at higher concentrations. There was no effect of pH on the flow properties of the β-glucans at lower concentrations of 1% while at higher concentrations of 4% and above viscosity increased with pH 4 or greater. A progressive decrease in viscosity with increasing temperature for all concentrations of samples tested at a constant shear rate was observed. A set gel structure was not formed below 3% β-glucan so 2% solutions were used to incorporate lactoferrin at room temperature prior to film casting and cryomilling to prepare microparticles. There was an initial burst lactoferrin release from all microparticles, with final amount released after 7 hours only 35 and 32 % for β-glucan alone or with the addition of PEG 2000 respectively. Final lactoferrin release after 7 hours was 91% when Kolicoat was added to the formulation. Stress studies on β-glucan indicated that there was no degradation of the β-glucan at gastric conditions of low pH, which suggests that β-glucan might protect fragile molecules under gastric conditions.