Effects of dextran sulfate, NaCl, and initial protein concentration on thermal stability of β-lactoglobulin and α-lactalbumin at neutral pH

The effects of NaCl, dextran sulfate (DS), and initial protein concentration on thermal stability of β-lactoglobulin (β-LG) and α-lactalbumin (α-LA) at pH 6.8 were investigated. NaCl was the biggest factor in accelerating protein aggregation as shown by an increase in turbidity, molecular size, and a decrease in protein solubility. DS at low concentration showed a protective effect against aggregation. Evidence suggested some degree of interaction between β-LG and DS. At higher concentration, phase separation between biopolymers favored aggregation, which resulted in an increase in turbidity and a reduction in protein solubility.