Charge domain of modified pectins influence interaction with acidified caseins

Abstract

The interaction of non-fat dry milk, caseinate and casein (CSN) fractions with charge modified pectins (B-Pec and U-Pec) and unmodified pectin (O-Pec) in acidified dispersion systems was investigated. U-Pec led to more precipitation of proteins than O-Pec or B-Pec. Casein dispersions with pectin had larger particle size, especially U-Pec and B-Pec, than dispersions without pectin. Dispersions with charge modified pectins showed more negative zeta-potential than dispersions with unmodified pectin or dispersions without pectin. U-Pec enhanced negative zeta-potential of beta-CSN more than B-Pec. There was no significant difference in flow behavior among non-fat milk samples regardless of pectins added. In contrast, non-Newtonian behavior, shear thinning behavior was observed in modified pectin added kappa-CSN. Analysis by light microscopy of non-fat milk and kappa-CSN showed that sizes and shapes were changed by addition of O-Pec and U-Pec. The results suggest a specific affinity between pectin and kappa-CSN, which is related to the charge distribution of pectin. (C) 2010 Elsevier Ltd. All rights reserved.