Effect of sucrose on the thermodynamic incompatibility of different biopolymers

The influence of sucrose on the thermodynamic incompatibility of a number of biopolymers in aqueous solutions has been studied. Three pairs of the biopolymers were chosen: sodium caseinate-ovalbumin, 11S globulin from vicia faba-ovalbumin and sodium caseinate-sodium alginate. The cosolubility of the biopolymers was investigated at different sucrose concentrations in solution (in the range 0-50% w/v). A big increase in the cosolubility of the biopolymers was observed with increasing sucrose concentration. It was established that the increasing cosolubility of the biopolymers occurs in accordance with the increase in the protein solubility in the aqueous medium on sucrose addition. It was supposed that the same factor provides the basis of both the increase in the solubility of proteins and the cosolubility of the biopolymers in the aqueous medium. The thermodynamic parameters of the different pair interactions (the second virial coefficients) were estimated using light scattering data in the binary and ternary aqueous solutions of the biopolymers without sucrose and on the addition of 25% w/v of sucrose. Copyright (C) 1996 Elsevier Science Ltd.