Stable Emulsions Constructed From Whey Protein Isolate-Arabinogalactan Conjugates: Preparation, Characterization, and β-Carotene Loading.

In this study, the results indicated that whey protein isolate-arabinogalactan (WPI-AG) conjugate emulsion exhibited optimal stability at pH 7.0 with a 25% oil phase volume fraction (φ), demonstrating the highest absolute zeta-potential value, the lowest interfacial tension, and excellent viscoelastic properties. Confocal laser scanning microscopy (CLSM) verified the development of a compact interfacial layer with high coverage. Furthermore, ultrasonication strengthened the stability of β-carotene-loaded WPI-AG oil-in-water (O/W) emulsions via mechanical shear, which reduced droplet size, increased the absolute zeta potential, and optimized the overall interfacial structure. These structural improvements led to significant enhancements in both physical stability (resistance to ionic, thermal, and pH stresses) and chemical stability (during storage and against light exposure). The 400 W treatment group indicated the most pronounced effects, with the highest cumulative release rate of β-carotene during in vitro digestion and a bioaccessibility of 81.98% ± 2.1%, which was markedly higher than that of the control group (49.55% ± 4.31%, p < 0.05). This work offers a theoretical basis for fabricating natural stable emulsions as delivery vehicles for lipophilic bioactive substances.