Stabilization and Rheology of Concentrated Emulsions Using the Natural Emulsifiers Quillaja Saponins and Rhamnolipids

Abstract

Concentrated emulsions are widely used in the cosmetic, personal-care, and food industries to reduce storage and transportation costs and to provide desirable characteristics. The current study aimed to produce concentrated emulsions (50 wt % oil) using two natural emulsifiers, quillaja saponins and rhamnolipids. The impacts of emulsifier concentrations on the particle sizes, rheological properties, and stabilities of concentrated emulsions were evaluated. Emulsion particle sizes were negatively correlated with the concentrations of both quillaja saponins and rhamnolipids, and rhamnolipids were more effective in producing smaller droplets. Both emulsifiers formed stable concentrated emulsions against a series of environmental stresses, including various temperatures (30-90 °C), salt concentrations (≤200 mM NaCl), and pHs (pH 5-8). The rheology tests suggested that concentrated emulsions stabilized by quillaja saponins or rhamnolipids presented shear-thinning behaviors and had relatively low consistency coefficients.

Nanoemulsions: Using emulsifiers from natural sources replacing synthetic ones—A review

“…Li, Dai, Wang, Mao, and Gao (2018) studied the production of concentrated emulsions (50% w/w oil phase) using two natural emulsifiers, quillaja saponins, and rhamnolipids. Emulsion droplet sizes were negatively correlated with the concentrations of both rhamnolipids, and quillaja saponins were more efficient in generating nanosize droplets (Li et al, 2018). Both emulsifiers showed the capacity to form stable concentrated NE against several environmental stresses including high thermal treatment (30 to 90 • C), high ionic strength (≤200 mM NaCl), and pH variation (pH 5 to 8).…”

Effect of Oil Content and Emulsifier Type on the Properties and Antioxidant Activity of Sea Buckthorn Oil-in-Water Emulsions

“…With sodium caseinate as the emulsifier, all the emulsions had high interfacial charges (|zeta-potential| > 30 mV), and the changes in homogenization pressure did not result in significant difference in zeta potential of the emulsions. To avoid droplet aggregation during homogenization, a sufficient interfacial coverage of emulsifier is essential [22]. When the oil droplets were not fully covered, emulsions usually had bigger particle size.…”

Formation of concentrated triglyceride nanoemulsions and nanogels: natural emulsifiers and high power ultrasound

“…46 This was suggested as a possible explanation for the higher apparent viscosity of the 50 wt% MCT emulsion prepared with Quillaja saponins (0.5-3 wt%) compared to the emulsion stabilized by rhamnolipids. 7…”

“…6 Furthermore, due to lower storage and transportation costs, they have immediate economic advantages, because they can be simply diluted at the formulation sites. 7 They can also turn to highly viscous or gel-like structures at much lower dispersed phase volume fractions than conventional emulsions. Such advantages could be useful in the production of low fat foods, with a consistency similar to original one, without using fat substitutes.…”