Inhibiting effect of dry heat on the heat-induced aggregation of egg white protein.

ABSTRACT

This study investigated the effect of dry heat on the aggregation characteristics of egg white protein (EWP) solutions. Turbidity and size-exclusion chromatography (SEC) results showed that dry heat hindered the subsequent bulk aggregation of dry heated EWP (DEWP) in aqueous solutions. A similar trend was also found in the particle size distribution of DEWP aggregates, where longer dry heating times resulted in smaller size distributions. Transmission electron microscopy (TEM) observations showed that native EWP tended to form bulk aggregates when heated in aqueous solutions, while DEWP aggregates presented linear and chain-like morphology. The α-helices of DEWP aggregates were converted to ß-sheets, and more chromogenic amino acids and hydrophobic groups were exposed owing to dry heat. Heat-induced aggregation of DEWP in water is more intense than that induced only by dry heat, but the hydrothermal aggregates with longer dry heating times were smaller in size and molecular weight.