Viscosity and Flocculation of Heated β-Lactoglobulin Solutions: Effect of Calcium Concentration and pH

Abstract

The effect of calcium concentration, pH, and heat on the physical properties of beta-lactoglobulin solutions was investigated. Viscosity, light transmission, and precipitation were measured. The dependence of viscosity on pH and the effect of certain alpha-amino group reagents suggested that alpha-amino groups assist in the binding of calcium ions. Precipitation in calcium-containing heated beta-lactoglobulin solutions was sharply dependent on pH; the lower the pH, the smaller the calcium concentration required. Calcium appears to function in large part to bring about an isoelectric precipitation by neutralizing negatively charged groups. The effects of heat on beta-lactoglobulin solutions are discussed in relation to heat stability of milk.