Preservation of (−)-Epigallocatechin-3-gallate Antioxidant Properties Loaded in Heat Treated β-Lactoglobulin Nanoparticles

(−)-Epigallocatechin-3-gallate (EGCG) was loaded in heat treated β-lactoglobulin (β-Lg) for the preservation of antioxidant activity. The effects of pH (2.5–7.0), the heating temperature of β-Lg (30–85 °C), the molar ratio of β-Lg to EGCG (1:2–1:32), and the β-Lg concentration (1–10 mg/mL) on the properties of β-Lg–EGCG complexes were studied. All four factors significantly influenced the particle size, the ζ-potential, and the entrapment efficiency of EGCG and EGCG loading in β-Lg particles. A stable and clear solution system could be obtained at pH 6.4–7.0. The highest protection of EGCG antioxidant activity was obtained with β-Lg heated at 85 °C and the molar ratio of 1:2 (β-Lg: EGCG). β-Lg–EGCG complexes were found to have the same secondary structure as native β-Lg.