Turbidity and rheological properties of bovine serum albumin/pectin coacervates: Effect of salt concentration and initial protein/polysaccharide ratio

The turbidity and theological properties of bovine serum albumin (BSA)/pectin coacervates show correlations with sodium chloride concentration (C-Nacl) and initial protein/polysaccharide ratio (r). Increasing C-Nacl from 0.01 to 0.4 M shifts the critical pH (pH(phi 1)), which designates as the critical pH for BSA/pectin coacervate formation, to lower values, and the storage modulus (G') values of BSA/pectin coacervates tend to be smaller, which can be explained by a salt screening effect in the BSA/pectin coacervates. Moreover, an increase of r from 1:1 to 10:1 favors the formation of BSA/pectin coacervates, as indicated by the increase in pH(phi 1) and the decrease in pH(phi 2). The values of G' increase simultaneously. With further increase of r to 20:1, the pH(phi 1) changes negligibly and G' values become much lower. These results reflect that a balance between the positive charges of BSA and the negative charges of pectin favors the formation of BSA/pectin coacervates with more compact network structures. (C) 2012 Elsevier Ltd. All rights reserved.