Rheological Properties of Heat-Induced β-Lactoglobulin Gels

Fonnation of heat-induced 13-lactoglobulin gels was studied by oscillation rheometry for up to 16 h at pH 4.5, 5, and 7 and a concentration of 3, 4, and 5% (wt/vol) protein. The absolute shear moduli (a measure of gel stiffness) continued to increase even after 16 h of aging. During aging, the character of the gels became progressively more elastic. De- spite a large variation in the dynamic moduli of the gels studied, their relative increase and the changes in loss tangent were very similar as a function of aging. The gels at pH greater than 6 were, over short time scales, relatively more elastic and less viscous. The influence of temperature was nearly the same for all gels. The shear moduli were generally proportional to the concentration to the power of 2.5.