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

The effect of the addition of a polysaccharide, kappa-carrageenan (KCG), on the properties of heat induced gels of a globular protein, beta-lactoglobu lin (BLG), was studied at pH 7 and 0.1 M NaCl The shear modulus was measure d as a function of heating time. At a given heating time and BLG concentrat ion, 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 attr ibuted to the effect of micro phase separation. Macroscopic phase separatio n is not observed, but can be easily induced by centrifugation. Transmissio n electron microscopy of gels with and without the addition of KCG demonstr ates the increased micro phase separation induced by KCG. (C) 1999 Publishe d by Elsevier Science Ltd. All rights reserved.