Green Tea Polyphenol-Stabilized Gel-Like High Internal Phase Pickering Emulsions

Food-grade high internal phase Pickering emulsions (HIPPEs), as a promising delivery system for functional substances used in the field of food, medicine, and cosmetics, have attracted considerable attention nowadays. However, most of these functional substances would be easily oxidized due to the sensitivity to oxygen, light, and heat. Therefore, it is crucial to find a new strategy which could efficiently improve the antioxidation of the Pickering system. Here, a novel antioxidative HIPPE stabilized by tea polyphenol nanoparticles (TPNPs) was prepared in this study. TPNPs with a high content of active epigallocatechin gallate component were used as stabilizers, and flaxseed oil was used as the oil phase in this Pickering system. The particle size, zeta potential, morphology, and wettability tests were carried out to investigate the feasibility of TPNPs as Pickering stabilizers. The results indicated that TPNPs with appropriate size (100–400 nm), spherical morphology, and medium wettability (θ_ow ≈ 90°) could meet the demands of Pickering stabilizers. The stability experiments showed that Pickering emulsions exhibited a remarkable physical stability (the emulsification index was up to 100%). Notably, the antioxidant assays demonstrated that the formed emulsion still performed a strong antioxidative capacity after one-month storage. Besides, the gel-like HIPPEs were also successfully obtained at low particle concentrations (1–2%) with the help of polyethylene glycol or just at the high particle concentrations (3–4%) in this study. The rheological measurements exhibited the highly stability of the gel-like emulsions. We expected that this work would be beneficial to the transportation and protection of sensitive functional compounds which could be better used in food, cosmetics, and pharmaceutical systems.