Stabilization of oil-in-water-in-oil (O1/W/O2) Pickering double emulsions by soluble and insoluble whey protein concentrate-gum Arabic complexes used as inner and outer interfaces

Soluble (SC) and insoluble (IC) complexes were obtained from interacting whey protein concentrate-gum Arabic, at pH of 4.0, using biopolymer mass ratios of 2:1 and 3:1, respectively. Particles (SPT) were produced from IC and dried at different temperatures. Higher temperatures induced a higher contact angle, modified the protein secondary structure to a greater extent, and decreased the interfacial tension to lower values. The O1/W primary emulsion and the O1/W/O2 double emulsions were stabilized with SC and SPT, respectively. The mean droplet size of the fresh primary emulsion and of the double emulsions increased to from 0.62 to 0.66 μm and from (9.34-4.35 to 10.45-4.63 μm) after 76 days of storage, respectively. Confocal micrographs permitted to observe the inner oil droplets surrounded by SC, and the double emulsion water droplets by SPT. Hydrophobic particles obtained from IC represent a viable alternative for substituting the use of synthetic surfactants in W/O2 interfaces.