Rhamnolipid as a unique emulsifier to stabilize sesame oil‐in‐water beverage emulsions formed by ultrasound‐induced cavitation: Optimizing the formulation and physical properties

Abstract

Rhamnolipid (RL) is a surfactant biosynthesized by Pseudomonas aeruginosa strains. The RL feasibility as a high-efficient emulsifier in increasing the physical stability of sesame oil (SO)-based beverage emulsions formed by the ultrasound-assisted emulsification process was studied. The concentration of SO (2.02%–6.98% wt/wt), and RL (0.49%–1.51% wt/wt) was adequately optimized based on the analysis of physical stability, turbidity loss rate (TLR), size index, density, and viscosity characteristics using the central composite rotatable design-response surface methodology. The overall optimum region to attain the highest stability (92.64%), viscosity ratio (0.338), and density (1.017 g/cm3), and the lowest TLR (0.216 Ǻ/day) and size index (0.240) based on the adequate second-order polynomial models (R2 = 0.956–0.991) was obtained at the combined level of 2.75% (wt/wt) SO and 0.662% (wt/wt) RL. No significant difference between the observed and predicted values fitted to second-order polynomial models was found. RL as an efficient biosurfactant can stabilize food-grade emulsion systems. Practical applications Sesame and its oil have some health-promoting properties such as antioxidative, antihypertensive, hypocholesterolemic, anticancer, and immunoregulation. There is a possibility to used SO in the development and production of beverages due to its high nutritional value in the prevention of chronic diseases. However, sesame has a slightly bitter aftertaste causing its low capita consumption. The emulsification as an efficient masking process can considerably reduce its bitter taste in the final product. Using rhamnolipid as a bio-emulsifier for this purpose is interesting. Beverage emulsion based on SO can be potentially interesting for consumers and beverage industries.