Preparation of salt-free Pleurotus eryngii protein with enhanced colloidal stability and emulsifying properties by ceramic membrane filtration

Fungi proteins represent a potential alternative to animal proteins, which are regarded as a prospective source of edible proteins due to more sustainable and efficient cultivation of fungi. Nevertheless, the extraction of fungi proteins typically involves alkali extraction combined with acid precipitation (AEAP), yielding considerable amounts of salt that causes aggregation and inferior functional properties of proteins. In this study, we put forward a novel extraction method by direct filtration of Na⁺ and OH⁻ from the alkaline extraction solutions using ceramic membranes. This method enabled the continuous, efficient and cost-effective production of Pleurotus eryngii protein (PEP). The PEP prepared by this technology featured a uniform distribution of nanoparticles (∼129.5 nm) with higher water dispersity, colloidal stability and surface active properties as compared to that prepared by the AEAP method. Moreover, the microstructures of PEP can be tailored with various nanoparticle sizes and size distribution profiles, allowing for the adjustment of long-term stabilities and surface activities. Our study renovated the production technology of fungi proteins to enhance their functionalities as well as the application prospects in the future food industry.