Abstract
Water-in-oil-in-water (W1/O/W2) emulsions are emulsion-based systems where the dispersed phase is an emulsion itself, offering great potential for the encapsulation of hydrophilic bioactive compounds. However, their formation and stabilization is still a challenge mainly due to water migration, which could be reduced by lipid phase gelation. This study aimed to assess the impact of lipid phase state being liquid or gelled using glyceryl stearate (GS) at 1% (w/w) as well as the hydrophilic emulsifier (T80: Tween 80 or lecithin) and the oil type (MCT:medium chain triglyceride or corn oil (CO) as long chain triglyceride) on the formation and stabilization of chlorophyllin W1/O/W2 emulsions. Their colloidal stability against temperature and light exposure conditions was evaluated. Gelling both lipid phases (MCT and CO) rendered smaller W1 droplets during the first emulsification step, followed by formation of W1/O/W2 emulsions with smaller W1/O droplet size and more stable against clarification. The stability of W1/O/W2 emulsions was sensitive to a temperature increase, which might be related to the lower gelling degree of the lipid phase at higher temperatures. This study provides valuable insight for the formation and stabilization of W1/O/W2 emulsions with gelled lipid phases as delivery systems of hydrophilic bioactive compounds under common food storage conditions.
Highlights
IntroductionWater-in-oil-in-water (W1 /O/W2 ) emulsions consist of a water-in-oil (W1 /O) emulsion dispersed in an outer aqueous phase
The most common method to fabricate W1 /O/W2 emulsions consist of a two-step process in which an initial step of making the W1 /O emulsion is followed by its dispersion in another aqueous phase [1]
The present work evidences that the formation and stabilization of double W1 /O/W2 emulsions can be enhanced with the use of gelled lipid phases
Summary
Water-in-oil-in-water (W1 /O/W2 ) emulsions consist of a water-in-oil (W1 /O) emulsion dispersed in an outer aqueous phase. Due to the compartmentalized internal structure, W1 /O/W2 emulsions offer great potential for the encapsulation and controlled release of hydrophilic bioactive compounds [2,3]. In these systems, multiple instability mechanisms can occur during their production and storage, such as coalescence of the lipid droplets and/or inner water droplets, and the coalescence of the inner water droplets with the outer water phase, which leads to water migration between both water phases. Polyglycerol ester of polyricinoleic acid (PGPR) has been demonstrated to be highly effective as W1 /O stabilizer, due to its ability to form small W1 droplets, and because it forms a physical barrier around these droplets preventing their coalescence [3,9]
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