Some structural properties of ovalbumin heated at 80°C in the dry state

Abstract

Dry heating of ovalbumin at 80°C improved the gel properties, including the gel strengthening and transparency upon the subsequent heating for gelation [Matsudomi, N., Ishimura, Y., & Kato, A., (1991). Improvement of gelling properties of ovalbumin by heating in dry state. Agricultural and Biological Chemistry, 55, 879–881.]. Some structural properties of the dry-heated ovalbumin responsible for such gel properties were studied. The electrophoretic patterns revealed the formation of ovalbumin polymer through hydrophobic and disulfide protein-protein interaction during heating in the dry state. The slight changes in circular dichroism spectrum and surface hydrophobicity indicated mild conformational changes in ovalbumin molecules. Differential scanning calorimetry themograms showed that enthalpy of denaturation of ovalbumin was markedly decreased with an increase of dry-heating time. The deamidation of ovalbumin was found to occur during the dry-heating process, and the degree of deamidation reached 10% after dry heating at 80°C for 7 days. It was assumed that the partially unfolded and deamidated ovalbumin produced by the dry heating forms specific soluble aggregates during subsequent heating for gelation, resulting in the formation of an ordered gel matrix.