Substitution of synthetic emulsifiers by a hemp protein in canola oil-in-water emulsions resembling salad dressing: comparison of rheological properties and physical stability

Hemp protein is a plant-based macromolecule considered a promising option for replacing synthetic emulsifiers in food formulations. This study evaluated the emulsifying potential of hemp protein isolate in canola oil-in-water emulsions. In the first stage, emulsion formulation was optimized using a factorial experimental design by varying guar gum (0.5-1.2 %), canola oil (15-30 %), and hydrophilic-lipophilic balance values (HLB) (11-15) achieved by blending Tween 80 and Span 20. Emulsions were characterized by measuring mean droplet diameters (D₃₂ and D₄₃), the Turbiscan Stability Index, and flow behavior. According to the design results, the formulation containing the highest gum and oil contents combined with the lowest HLB value demonstrated the greatest physical stability and was selected to continue the investigation. In the second stage, synthetic surfactants were replaced with 3.0 % hemp protein isolate. The resulting emulsions exhibited shear-thinning behavior, a weak gel-like structure and viscoelastic properties suitable for salad dressing applications and remained physically stable for 14 days. The formation of a weak flocculated protein network contributed to emulsion stabilization by limiting droplet movement and inhibiting coalescence. These results demonstrate that hemp protein isolate is a viable alternative to synthetic surfactants in emulsified food systems, offering desirable physical and rheological properties.