The rheological behaviour of low fat soy‐based salad dressing

Summary Low fat soy‐based salad dressings were formulated with different oil levels (3%, 13% and 23%) and emulsifiers (whey protein concentrate, soy‐lecithin and sodium caseinate) using either blender or ultra‐turrax (UT) homogeniser. Results showed that the rheological behaviour of these samples were highly dependent on the oil content, emulsifiers and blending methods. The UT method produced samples with better viscosity and have droplet size of 2–100 μm. Samples containing higher oil level have higher viscosity, smaller droplet size, larger G ′ and G ″ values. All samples show a shear‐thinning effect and larger G ′ than G ″, indicating the elastic nature of the samples. A quantity Q ( t )% was applied to estimate the elasticity and the values were found to be in the range 22.8–85.2%. G ′ and G ″ were found to decrease with increased temperature. However, tan δ increased slightly with temperature; the values ranged from 0.2 to 0.4 at 5 °C to 0.3–0.5 at 25 °C. Current results demonstrated that the formulated samples have good stability compared with commercial products.