Structural properties of condensed ovalbumin systems following application of high pressure
Abstract The effect of high pressure on thermomechanical and physicochemical properties of ovalbumin samples up to 80% (w/w) solids is presented and compared to conventional thermal treatment. Results from small deformation dynamic oscillation in shear, modulated differential scanning calorimetry (MDSC) and Fourier transform infrared spectroscopy (FTIR) revealed that pressure treated ovalbumin maintains its native conformation in condensed systems of 80% (w/w) solids, whereas its structure has been irreversibly changed in the aqueous environment of 20% (w/w) solids, and partially altered at intermediate levels of solids (30 60% w/w) That was rationalized on the basis of specific rearrangements between sulfhydryl and disulphide bonds following application of high pressure and the high hydrophobicity of the ovalbumin molecule. Cooling to subzero temperatures results in vitrification and the formation of a matrix with glassy consistency for both atmospheric and pressurised materials. Application of the method of reduced variables and the combined WLF/free volume theoretical framework are able to predict the glass transition temperature of condensed ovalbumin preparations.