Caseinomacropeptide modifies the heat-induced denaturation–aggregation process of β-lactoglobulin

The effect of caseinomacropeptide (CMP) concentration on the kinetics of denaturation of β-lactoglobulin (β-Lg) and on the size and structure of the heat-induced aggregates was investigated over a wide range of pH (3.0–6.7) and temperature (65–95 °C). Irrespective of pH and heating temperature, CMP increased the rate of β-Lg denaturation. When β-Lg and CMP were negatively charged (i.e., at pH 6.7), increasing CMP concentration hindered aggregate formation; the aggregates had a smaller hydrodynamic diameter and the protein solution turbidity decreased. However, when β-Lg and CMP were oppositely charged (i.e., at pH 4.0), CMP promoted aggregate formation and large particles (>5 μm) were formed on heating. Nevertheless, the covalent aggregates constituting these large particles were of smaller size than those formed on heating β-Lg in the absence of CMP. At pH 4.0, CMP induced the formation of large particles when added in a solution of preformed aggregates of β-Lg.