Oxidative Stability and Rheological Properties of Oil-In-Water Emulsions with Walnut Oil

The oxidative stability of walnut oil and oil-in-water (O/W) emulsions with walnut oil stabilized by soy protein isolate (SI) and Whey Protein Isolate (WPI) was evaluated. The food emulsions were more stable than walnut oil, as indicated by measuring the formation of primary and secondary oxidation products. It was shown that the emulsions with WPI had a better oxidative stability than the emulsions with SI, probably due to the ability of whey proteins to inactivate peroxil radicals. In addition, the basic rheological characteristics: apparent and plastic viscosities, yield stress, consistency coefficient, and flow behavior index of the evaluated O/W emulsions, were determined. The rheological behavior and flow curves were analyzed using a fitted power law and Herschel-Bulkley model. The emulsions with SI showed increased viscosity in comparison to WPI emulsions. Moreover, soy protein formed a continuous network, and emulsions were more stable to creaming.