INTERACTIONS BETWEEN FOOD STABILIZERS AND BETA-LACTOGLOBULIN

β-Lactoglobulin forms insoluble complexes with anionic polysaccharides under specified conditions of pH and ionic strength. No complexing with neutral polysaccharides was detected. For the weakly acidic carboxymethylcellulose (CMC), maximum interaction occurred at pH 4 provided the ionic strength was below 0.1. Under these conditions, the binding ratio was 45.3 ± 4.6 moles of carboxyl groups per mole of β-lactoglobulin. Further addition of CMC resulted in a peptization of the insoluble complex. For the strongly acidic carrageenan types and sulfated cellulose, similar interactions also occurred at low pH, but the complexes were not as readily dissociated by increasing the ionic concentration as were the complexes with CMC. These findings suggest that the complex formation is the result of ionic attractions between the positively charged protein and the negatively charged stabilizers. The presence of CMC during heating of β-lactoglobulin afforded some protection against denaturation of the protein at neutral pH, as measured by the depression in the amount of heat-exposed sulfhydryls. © 1969, American Chemical Society. All rights reserved.