Physicochemical and emulsifying properties of protein isolated from Phlebopus portentosus

Edible mushroom proteins have attracted increasing interest due to their high content and nutritional quality. In the present work, Phlebopus portentosus protein isolate (PPI) was extracted from P. portentosus fruiting bodies using alkali extraction and isoelectric precipitation method, and the physicochemical and emulsifying properties of PPI were systematically investigated. PPI had a good balance of essential amino acids, but showed low solubility in water. Therefore, a protein nanoparticulation strategy was used to prepare stable PPI nanoparticle (PPIP) dispersions. PPIP showed an average diameter of 225.91 nm, an oil-in-water three-phase contact angle (θo/w) of 95.62°, and fast adsorption behavior at the oil-water interfaces. The near-neutral wettability and high interfacial ability facilitate PPIP as a single emulsifier to fabricate a double Pickering emulsion via the one-step homogenization. The properties of PPIP-stabilized double emulsions were dependent on the protein concentration and oil content. For example, an increase in protein concentration resulted in the decrease of small internal droplet number, droplet size, and storage modulus; an increase in oil content also led to the decrease in the droplet size. These results suggest that PPI has a great potential to be used as emulsifiers for preparing double emulsions.