Influence of Aqueous Phase Composition on Double Emulsion Stability and Colour Retention of Encapsulated Anthocyanins

Abstract

Water-in-oil-in-water (W1/O/W2) emulsions (double emulsions) have often been used for the encapsulation of bioactive compounds such as anthocyanins. Instability of both anthocyanins and double emulsions creates a need for a tailored composition of the aqueous phase. In this work, double emulsions with a gelled internal water phase were produced and monitored over a 20-day storage period. The effect of the electrolyte phase composition (varying electrolyte components, including adipic acid, citric acid, and varying concentration of potassium chloride (KCl)) on anthocyanin and double emulsion stability was analysed using colour analysis, droplet sizing, and emulsion rheology. The effect of electrolytes on colour retention was shown to differ between the primary W1/O emulsion and the secondary W1/O/W2 emulsion. Furthermore, droplet size analysis and emulsion rheology highlighted significant differences in the stability and structural behaviour of the emulsions as a function of electrolyte composition. In terms of colour retention and emulsion stability, a citrate-buffered system performed best. The results of this study highlight the importance of strict control of aqueous phase constituents to prevent anthocyanin degradation and maximise double emulsion stability. Additional experiments analysed the effect of pectin chemistry on the anthocyanin colour retention and leakage, finding no conclusive difference between the unmodified and amidated pectin.

Preparation of vitamin D3-loaded oil-in-water-in-oil double emulsions using psyllium gum: optimization using response surface methodology

“…Oil-in-water nano emulsions are preferably suitable for the encapsulation and delivery of fat-soluble vitamins, due to the small oil droplets being rapidly digested within the human gastrointestinal tract (GIT), thereby fast generating mixed micelles enable solubilizing and transporting them [16]. Some research focused on the application of double emulsions for encapsulation of various components, such as double emulsion encapsulation for Sambucus nigra L. coloring systems, [17] pomegranate peel extract (Punica granatum L.), [18] anthocyanins, [19] β-carotene [13]. Double emulsions were studied for encapsulation of various vitamins, such as resveratrol or vitamin B12, [20] calcium and vitamin D3, [21] trans-resveratrol, and vitamin D3 [22].…”

Application of Emulsion Gels as Fat Substitutes in Meat Products

“…During storage, double emulsions may exhibit creaming, phase inversion, phase separation, flocculation, and coalescence [120]. Gelation is a feasible method for improving stability [121,122]. The gelation of the inner aqueous droplets in the double emulsions via the incorporation of polymers or proteins into the inner droplets increases the stability against heat, shear, and the presence of salts.…”

Progress in the Application of Food-Grade Emulsions

“…Specifically, they can act as carriers for the packaging; protection; and delivery of active ingredients (e.g., curcumin, capsaicin, probiotics, and phytochemicals) to improve product stability, solubility, flavor, and taste. Therefore, the development of emulsion delivery systems, such as natural oil–body emulsions, conventional emulsions, nanoemulsions, Pickering emulsions, double emulsion [ 1 ], blended emulsions [ 2 ], HIPEs, and self-emulsifying formulations, promotes the innovative application of functionally active substances and is currently an emerging area in the research on foods, pharmaceuticals, materials, and fine chemicals. For example, soft materials exhibiting a range of properties have been designed and delivered using various emulsion carrier technologies to take advantage of the different dispersed-phase properties.…”

“…Double emulsions generally contain three (or more) immiscible liquids (W/O/W, O/W/O, etc.) [ 1 ]. Blended emulsions usually refer to the mixing of two or more emulsions from different sources (such as soy–cow-blended milk) [ 2 ].…”