Effect of Sucrose Addition and Heat Treatment on Egg Albumen Protein Gelation

Abstract

ABSTRACT: Studies were conducted to evaluate the effect of sucrose (0% to 60% w/w) on the heat denaturation and gelation of egg albumen solutions (pH 7.0) by thermal analysis and rheological measurements. Temperature and frequency sweeps were carried out under small deformations to determine the temperature at which structure development began (Ts) and the storage modulus plateau (G0), respectively. The latter was used to estimate the molecular weight of the internal chains between cross-links (Mc) using the rubber elasticity theory. Gels were prepared under several heat intensities (70, 80, and 90°C/30 min), and the mechanical properties were determined under small (stress relaxation) and large (stress and strain at fracture) deformations. It was observed that increments in sucrose concentration could act in the stabilization of the proteins, promoting a significant increase in the onset values and temperature of denaturation. The gelling process showed aTs increase with higher sucrose concentration. Gelation and the gel mechanical properties and network density showed a strong dependence on sucrose concentration and heat treatment temperature. In a general way, the sucrose promoted an improvement in the gel network up to a determined value of sugar concentration. At higher sugar concentrations, the values for the rheological properties decreased, which could be related to an incomplete unfolding of the oval-bumin under these conditions.