Stabilization of whey protein isolate-pectin complexes by heat.

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.