Heat-Induced Gelation of Globular Proteins. 1. Model for the Effects of Time and Temperature on the Gelation Time of BSA Gels

Abstract

Globular protein gels have been extensively investigated over many years, although the great majority of studies have used rather crude and/or mixed samples of protein. Moreover, most previous work has concentrated on examining structural and rheological properties of fully cured gels. In the present paper we will discuss heat-induced gelation of the typical globular protein, bovine serum albumin (BSA), not far from critical gel conditions together with aspects of kinetic gelation theory. We will concentrate on a description of the parameters that alter the gelation or gel time, t c . We will develop a new model to describe both the effect of temperature and polymer concentration on t c . Gel formation is achieved by isothermal heating. The change in rheological properties during the gelation process is monitored by dynamic shear rheometry as a function of time. The measurements are carried out at different temperatures and protein concentrations to clarify their effects on the gelation. The results are displayed in various diagrams, including a new form of sol/gel state diagram, and discussed in terms of both phase behavior and gelation kinetics.