Whey protein-gallic acid-pectin covalent conjugates improved emulsion stability and bioaccessibility of β-carotene.

β-carotene is a bioactive lipophilic compound, but its low water solubility and environmental sensitivity limit its use in food industry. In this study, β-carotene-loaded oil/water emulsions were constructed using whey protein (WP)-gallic acid (GA)-pectin (PC) ternary covalent conjugates as interfacial stabilizers, and the relationship among pH-dependent interfacial behavior, emulsion stability, and β-carotene digestion characteristics were investigated. The WP-GA-PC conjugate exhibited the most favorable interfacial adsorption behavior at pH 5 and formed a more elastic interfacial film, resulting in emulsions with the smallest particle size (30.51 μm) and excellent thermal and salt ion stability. Rheological analysis showed that all emulsions exhibited shear-thinning behavior, while pH value markedly affected their apparent viscosity. The encapsulation rates of β-carotene in pure oil, WP, WP-GA and WP-GA-PC emulsions were 70.83%, 90.07%, 93.17% and 96.25%, respectively. The bioaccessibility of β-carotene was 13.73% and 8.67% higher in WP-GA-PC emulsion than in WP emulsion and WP-GA emulsion, respectively. This work provides a scientific basis for designing protein-polyphenol-polysaccharide covalent conjugate-based emulsion delivery systems for lipophilic bioactive compounds.