| Three model systems using solutions of whey protein isolate (WPI) in water; mixed with pectin; or tomato juice, were produced at pH 3.3, 3.7, or 4.2 to study interactions of whey proteins and pectin.;Incorporation of whey proteins had a favorable effect in the spray drying of tomato juice and in blends containing fresh whey at pH 3.3 and 4.2; however, visual sedimentation was observed in reconstituted mixtures due to the drying process.;This investigation confirmed the complexation of whey proteins and pectin at pH lower than 3.9 leading to the development of visual sedimentation. Whey proteins precipitated following heating below pH 3.9 but resisted coagulation and sedimentation at pH 4.2 in the presence of pectin. The pectin reactivity in tomato juice and its complexation with whey proteins at the pH range studied was illustrated indirectly by measuring sediment formation, its composition and the viscosity of WPI-tomato juice systems. |
