Thermal denaturation and aggregation of egg proteins

The thermal denaturation of egg white and egg yolk proteins has been investigated by means of differential scanning calorimetry in natural, spontaneously aged samples. pH and protein content change with ageing. The overall endothermic signal from fresh egg white has been deconvoluted into three main gaussian components relevant to the denaturation of conalbumin, Iysozyme and ovoalbumin. The main modifications of the denaturation signal in aged egg white are attributed to progressive conversion of ovoalbumin to intermediate and Sovoalbumin conformations denatured at slightly higher temperatures. Aggregation of denatured proteins gives an exothermic signal that partially overlaps the denaturation peak. This implies some uncertainty in evaluation of each thermal effect, especially for non-aged samples. Nonetheless, the results obtained are comparable with the latest literature data on aqueous solutions of individual proteins. No deconvolution has been attempted for the endothermic DSC signal from egg yolk samples in the absence of literature on the DSC investigation of individual yolk proteins.