Relating water holding of ovalbumin gels to aggregate structure

Abstract

To increase understanding of water holding in heat-set ovalbumin gels, the relation between aggregate structure (both in solution and in gels) and gel coarseness or gel stiffness is studied. The aggregate morphology obtained by preparation of ovalbumin gels between pH 5.8 and 6.8 differs, as shown by a combination of light scattering, confocal microscopy, electron microscopy and neutron scattering techniques. It is shown that with decreasing pH larger aggregates are formed that are more compact, indicated by the fractal dimension that increased from 1.9 to 2.6. Furthermore, larger, more compact aggregates at pH 5.8 as compared to pH 6.8 resulted in more coarse gels with a less merged microstructures. In addition, a lower gel stiffness is observed at lower pH. The combination of a higher coarseness and lower gel stiffness explains both the lower total water holding and the easier exudation of water from the gel upon applied forces.