SPECIFIC DIVALENT CATION-INDUCED CHANGES DURING GELATION OF BETA-LACTOGLOBULIN

Thermally induced gelation of beta-lactoglobulin sols that contained NaCl and/or CaCI2 at pH 7.0 and the rheological properties of the resulting gels were investigated. Gels containing 20 mM CaCI2 were more deformable than gels containing 100 mM NaCl since a greater shear strain was required to achieve fracture. Investigating the gelation process by small-strain dynamic rheology showed that beta-lactoglobulin sols containing 20 mM CaCI2 gelled more rapidly and had lower gel points than similar sols containing 100 mM NaCl. Following gelation at 80-degrees-C and cooling to 25-degrees-C, gels containing 100 mM NaCl had greater values for G' (storage modulus) than those containing 20 mM CaCI2. These cation-dependent differences in gelation and rheological properties of the gels could not be explained by cation-associated differences in structure or denaturation characteristics determined by circular dichroism measurements.