Phase segregation of amylopectin and β-lactoglobulin in aqueous system

Phase behavior of aqueous amylopectin and β-lactoglobulin system was studied using Fourier transform infrared spectroscopy. Polysaccharide–protein mixtures were prepared at different concentrations and left for equilibration; afterwards their spectra were recorded and correlated using Partial Least Square analysis. Tertiary phase diagrams were built for the system at different equilibration times (2 and 6 weeks); the binodals were asymmetric and displayed toward the protein concentration. In the two-phase region of the phase diagrams the mixtures showed an upper layer rich in β-lactoglobulin and a lower layer rich in retrograded amylopectin, and in some cases an intermediate layer was seen which was a metastable phase.