Conclusions
We have shown that biopolymer particles can be prepared by heating globular protein–polysaccharide complexes above the thermal denaturation temperature of the proteins. These biopolymer particles are relatively small (d ≈ 300 nm) and are stable over a relatively wide range of pH values, which depends on polysaccharide concentration. At sufficiently high polysaccharide concentrations, biopolymer particles could be formed that remained intact from pH 3 to 7, which covers most of the range important for food applications. Compositional analysis suggested that the biopolymer particles formed were comprised primarily of β-Lg, but that some pectin may also be present. These biopolymer particles could be used as fat mimetics (e.g., to simulate the light scattering or viscosity of fat droplet suspensions) or they could be used as delivery systems (e.g., to encapsulate bioactive components). Further work is needed to better understand the molecular and structural events that occur when globular proteins undergo thermal denaturation and aggregation within a protein–polysaccharide electrostatic complex.
Acknowledgements
This material is based upon work supported by the Cooperative State Research, Extension, Education Service, United State Department of Agriculture, Massachusetts Agricultural Experiment Station and an United States Department of Agriculture, CREES, NRI Grant (Award Number 2005-01357).