Influence of sucrose on the thermal denaturation, gelation, and emulsion stabilization of whey proteins

The influence of sucrose (0-40 wt %) on the thermal denaturation and functi onality of whey protein isolate (WPI) solutions has been studied. The effec t of sucrose on the heat denaturation of 0.2 wt % WPI solutions (pH 7.0) wa s measured using differential scanning calorimetry. Sucrose increased the t emperature at which protein denaturation occurred, for example, by 6-8 degr ees C for 40 wt % sucrose. The dynamic shear rheology of 10 wt % WPI soluti ons (pH 7.0, 100 mM NaCl) was monitored as they were heated from 30 to 90 d egrees C and then cooled to 30 degrees C. Sucrose increased the gelation te mperature and the final rigidity of the cooled gels. The degree of floccula tion in 10 wt % oil-in-water emulsions stabilized by 1 wt % WPI (pH 7.0, 10 0 mM NaCl) was measured using a light scattering technique after they were heated at fixed temperatures from 30 to 90 degrees C for 15 min and then co oled to 30 degrees C. Sucrose increased the temperature at which maximum fl occulation was observed and increased the extent of droplet flocculation. T hese results are interpreted in terms of the influence of sucrose on the th ermal unfolding and aggregation of protein molecules.