Preparation and Properties of Walnut Protein Isolate-Anthocyanin Stabilized Pickering Emulsion

Composite particles were prepared from walnut protein isolate (WalPI) and anthocyanin (ACN), and used to stabilize Pickering emulsions. The effects of different ACN additions (0.05%~0.15%) on the particle size, zeta potential, Fourier transform infrared spectroscopy, surface hydrophobicity, and thermal stability of the composite particles were investigated, and the properties of Pickering emulsions were studied in terms of droplet size, microstructure, storage stability, and rheological properties. The results showed that WalPI combined with ACN to form large particles, electrostatic interactions, hydrogen bonding, and hydrophobic interactions existed between the two. And ACN improved the hydrophilicity and thermal stability of WalPI. The particle size and thermal denaturation temperature of the zeta potential of the composite particles were 299.1 nm, −19.47 mW, and 85.86 ℃, respectively, with the best overall performance when ACN was added at 0.05%. The average droplet size of the Pickering emulsion stabilized by WalPI-ACN was less than 16 μm, with a single-peaked homogeneous distribution, a non-Newtonian fluid with pseudoplastic characteristics. When ACN was added at 0.05%, the average droplet size of Pickering emulsion was 7.04 μm, with good dispersibility. Its droplets showed a complete circular structure with a CI of 1.48% after 15 days of storage. The system exhibited high apparent viscosity and stress, forming an elastic-based gel-like structure, which contributed to its optimal overall performance. This study may provide new ideas for the potential application of protein-polyphenol composite particles in the food industry and the development of food-grade Pickering emulsions.