Fabrication of whey-protein-stabilized G/O/W emulsion for the encapsulation and retention of l-ascorbic acid and α-tocopherol

Abstract

Water in oil in water (W1/O/W2) emulsion is a potential carrier for the simultaneous encapsulation of hydrophilic and lipophilic bioactive components. A major challenge of W1/O/W2 emulsion is its physical instability, due to the passage of water molecules from the inner to outer water phase. The gelation of the internal aqueous phase is a promising strategy for the stabilization of double emulsion. The current study aimed at fabrication of gelled water in oil in water (W/W) emulsion by cold-set gelation of pre-heated whey protein isolate (WPI) in inner aqueous phase induced by sodium chloride and its combination with l-ascorbic acid (L-AA) and addition of native WPI in the external aqueous phase. L-AA was not only used as a hydrophilic bioactive component but also a gelling agent. The formation and stabilization of gelled water in oil (G/O) and G/O/W emulsions were optimized by different compositions in the internal aqueous phase and emulsification methods and characterized in term of morphological structure and size distribution. All G/O/W emulsions showed Newtonian fluid behavior when they were developed using T-channel module and extrusion module with cellulose acetate membrane. The G/O/W emulsions had a size of 7.21–9.93 μm and kept multiple-compartment after storage. The co-encapsulation in G/O/W emulsions improved the stability of L-AA and α-tocopherol, with their retention being 76% at 25 °C after 15 days.