Stabilization of Whey Protein Isolate−Pectin Complexes by Heat

Abstract

Protein-polysaccharide complexes formed under electrostatic associative conditions could have interesting functional properties. However, their stability over a wide range of pH limits their widespread application. The aim of this work was to determine the time-temperature combination required to stabilize whey protein isolate (WPI) and pectin (LMP) complexes formed at pH 4.5 to a further pH adjustment to 7. The effect of storage for 28 days at 4 degrees C was also evaluated. Stability was confirmed by quantification of sugar and nitrogen in each phase after centrifugation. Three heat treatments were performed: 73 degrees C/5 min, 85 degrees C/15 min, and 90 degrees C/2 min. At 73 degrees C/5 min, adjustment to neutral pH led to disruption of WPI-LMP complexes. The most severe heating conditions (85 and 90 degrees C) allowed the stabilization of WPI-LMP complexes. Heated complexes (90 degrees C) could be preserved for up to 28 days of storage at 4 degrees C without affecting their stability.

Effect of pH on the properties of soy protein–pectin complexes

“…In other systems it has been shown that heating can stabilize protein-polysaccharide complexes to further pH adjustments (Jones, Decker, & McClements, 2009;Gentes et al, 2010). Regardless of the mechanism, the fact that thermal treatment enhances the solubility of SPI:PEC complexes is an important finding from the point of view of producing a shelf-stable food product that could be pasteurized.…”

“…We also consider the effects of thermal processing on these complexes. Some previous reports have documented that proteinpectin complexes may be stabilized by heat (Gentes, St-Gelais, & Turgeon, 2010), however no description is available for soy proteinpectin complexes. Finally, we demonstrate similar functionality can be achieved in SPI:PEC complexes at product produced at pilot scale.…”

Characterization of the interactions between chitosan/whey protein at different conditions

“…These interactions can be adopted to obtain different functionalities. For instance, Co-soluble polysaccharides can be used to improve heat stability of protein-enriched beverage (Gentès et al, 2010), protein/polysaccharide nanoparticles formed based on associative interaction can be used as carrier of bioactive compounds with improved bio-availability (Lee et al, 2012).…”

Water-binding of protein particles

“…This led to the formation of aggregated protein molecules. The second step was lowering of the pH to the isoelectric point of the whey proteins (pH 5.2-5.4), [58][147] which resulted in phase separation and spontaneous restructuring of the proteins at the molecular level. When shearing or mixing was applied during incubation, forced-assembly also played a role during MP formation.…”

“…In the first step, whey proteins are turned into reactive aggregates by mildly heating a protein solution with a concentration lower than the critical gelation concentration (11-12%), [7][90] at low ionic strength; and a pH above or below its isoelectric point (pH 5.2-5.4). [58][ 147] This results in the formation of protein aggregates with a hydrodynamic diameter of about 80 nm.…”