Stability of Anthocyanin‐Rich W/O/W‐Emulsions Designed for Intestinal Release in Gastrointestinal Environment

Abstract

Anthocyanins belong to the most important hydrophilic plant pigments. Outside their natural environment, these molecules are extremely unstable. Encapsulating them in submicron-sized containers is one possibility to stabilize them for the use in bioactivity studies or functional foods. The containers have to be designed for a target release in the human gastrointestinal system. In this contribution, an anthocyanin-rich bilberry extract was encapsulated in the inner aqueous phase of water-in-oil-in-water-double emulsions. The physical stability as well as the release of free fatty acids and encapsulated, bioactive substances from the emulsions during an in vitro gastrointestinal passage were investigated. The focus was on the influence of emulsion microstructural parameters (for example, inner and outer droplet size, disperse phase content) and required additives (emulsifier systems), respectively. It could be shown that it is possible to stabilize anthocyanins in the inner phase of double emulsions. The release rate of free fatty acids during incubation was independent of the emulsifier used. However, the exterior (O/W)-emulsifier has an impact on the stability of multiple emulsions in gastrointestinal environment and, thus, the location of release. Long-chained emulsifiers like whey proteins are most suitable to transport a maximum amount of bioactive substances to the effective location, being the small intestine for anthocyanins. In addition, it was shown that the dominating release mechanism for entrapped matter was coalescence of the interior W(1) -droplets with the surrounding W(2) -phase.

Understanding Food Structures

“…First, there is the capability to encapsulate a sensitive ingredient such as a hydrophilic nutrient or flavor compound within the inner aqueous phase, and then to release it at a controlled rate in response to some external trigger during eating/digestion. For instance, a protein-stabilized double emulsion formulation with encapsulation and release of anthocyanins under gastrointestinal conditions has been reported (Frank et al, 2012). The second area of potential application lies in reduced-fat product development where a conventional O/W emulsion is replaced by an equivalent amount of W/O/W emulsion of lower absolute oil content but similarly perceived fat content .…”

Food Engineering at Multiple Scales: Case Studies, Challenges and the Future—A European Perspective

“…We have designed emulsions with multiple functions for the droplet phase: (i) solvent for the active molecules; (ii) stabilization of sensitive components against UV radiation, oxidation and other chemical reactions; (iii) suitability for uses with active molecules in products with a high consumer preference; (iv) transportation of active molecules through the intestinal tract and controlled release at a targeted site and rate. Multiple emulsions, such as water-in-oil-in-water systems (W/O/W), were found promising and investigated for the use as vehicles for the delivery of the active molecules [39,40]. Active molecules were encapsulated in the inner aqueous phase with diameters over the range of 50-1000 nm.…”

Spray dried double emulsions containing procyanidin-rich extracts produced by premix membrane emulsification: Effect of interfacial composition

“…Water-in-oil-in-water (W 1 /O/W 2 ) emulsions are used as a carrier for hydrophilic bioactive compounds by loading them in the inner water phase (W 1 ). Frank et al (2012) and Hemar, Cheng, Oliver, Sanguansri, and Augustin (2010) have encapsulated anthocyanins and resveratrol from grapes in double emulsions, respectively. However, the use of W 1 /O/W 2 emulsions is not yet widespread because of their low stability during storage compared to single emulsions (O/W or W/O).…”