Formation and characterization of lactoferrin/pectin electrostatic complexes: Impact of composition, pH and thermal treatment

Protein-polysaccharide complexes may be used for the development of delivery systems with applications in several industries. In the present work, the interaction of lactoferrin (LF, 0.2wt%) with a High-Methoxyl pectin (0.005-0.15wt%) in aqueous solutions was studied at different pH values (2-7) and temperatures (30-90 degrees C) at low ionic strength. zeta-potential and light-scattering techniques were used to provide information about the electrical charge and aggregation of individual biopolymers and complexes. At pH 7, the electrical charge went from positive to negative when increasing amounts of pectin were added to the LF solution, which was attributed to the formation of an electrostatic complex. These complexes remained soluble (low turbidity) from pH 7 to 3.5, but became turbid between pH 3.5 and 2, due to charge neutralization and bridging effects. At pH 7, the stability of LF-pectin complexes to aggregation during heating was much better than LF alone. The results of this study should provide information that will facilitate the utilization of lactoferrin as a bioactive component in food systems. (C) 2010 Elsevier Ltd. All rights reserved.