Effect of addition of kappa-carrageenan on the mechanical and structural properties of betalactoglobulin gels

The effect of the addition of a polysaccharide, kappa-carrageenan (KCG), on the properties of heat induced gels of a globular protein, beta-lactoglobulin (BLG), was studied at pH 7 and 0.1 M NaCl The shear modulus was measured as a function of heating time. At a given heating time and BLG concentration, the shear modulus has a maximum as a function of the KCG concentration. The initial increase can be attributed to the increase of the kinetics of the aggregation of BLG induced by KCG. The subsequent decrease can be attributed to the effect of micro phase separation. Macroscopic phase separation is not observed, but can be easily induced by centrifugation. Transmission electron microscopy of gels with and without the addition of KCG demonstrates the increased micro phase separation induced by KCG.