Encapsulation of resveratrol using food-grade concentrated double emulsions: Emulsion characterization and rheological behaviour

The aim of this work was to prepare concentrated water-in-oil-in-water (W1/O/W2) double emulsions to entrap resveratrol (RSV) with high encapsulation efficiency, good stability, and appropriate rheological behaviour. W1/O was formulated with an ethanol/water RSV solution (W1) dispersed in Miglyol 812 (O) (20 vol%) with polyglycerol polyricinoleate as stabiliser. W2 was a 2% w/v Tween 20 solution with and without sodium carboximethylcellulose as thickening agent. Different volumetric ratios (20/80 to 80/20) of W1/O dispersed into W2 were used. W1/O/W2 emulsions were characterized in terms of visual inspection, droplet size distribution, and stability. The rheology of these double emulsions was fully studied. Actual encapsulation efficiency was determined considering the non-encapsulated RSV recovery yield. The concentrated W1/O/W2 double emulsions with the optimum formulation showed high encapsulation efficiency (up to 58%), good storage stability, shear-thinning behaviour, and dominant elastic character, with 6.2 mg/L of encapsulated RSV. These double emulsions may be suitable for food applications.