Protein isolate from Stauntonia brachyanthera seed: Chemical characterization, functional properties, and emulsifying performance after heat treatment

The seed of Stauntonia brachyanthera is usually regarded as waste after fructus processing. Here, the potential utilization value of the protein isolate (SSPI) from seeds was evaluated by investigating its physicochemical and functional properties. SSPI was a complex protein containing 7 distinct subunits that had high contents of most essential amino acids. The maximum foaming capacity of SSPI was 406.7 +/- 41% at pH 9.0, and the water holding/oil adsorption capacities were 4.66 g/g and 9.06 g/g, respectively. SSPI aggregates with a particle size of 154.1 +/- 5.2 nm was prepared after heat treatment, which was performed as a Pickering-like stabilizer for the structuring of water-in-oil-in-water emulsions. The outer droplet size of emulsions decreased as the aggregate concentration increased. Emulsion gels could be observed with the increasing aggregate concentration and oil fraction. Further study found that the stabilities of inner water-in-oil droplets and creaming were progressively increased by increasing the aggregate concentration during storage.