In vitro gastrointestinal digestion and fecal fermentation of Pleurotus eryngii protein extracted using different methods-insights for the utilization of edible mushroom-based proteins as novel nutrient and functional component

Pleurotus eryngii protein is considered high quality protein based on its rich and comprehensive essential amino acids, and has also been proved displaying multiple significant functional characterizations of which vary with its fabrication process. We aimed to investigate the variation differences of P. eryngii protein extracted by alkaline extraction and acid precipitation (AA), cellulase complex alkaline extraction and acid precipitation (CAA), ultrasound assisted alkaline extraction and acid precipitation (UAA), and salt dissolution method (S) from the perspective of gastrointestinal digestion and fecal fermentation consequences. Protein hydrolysis and structural analysis was performed on after in vitro gastrointestinal digestion, and found that AA had the highest hydrolysis degree while CAA had the lowest. The results of fluorescence chromatography and infrared chromatography indicated that the reasons for the digestion difference might be the unfolding degrees of protein tertiary structure and the polysaccharide which was the highly contained component in crude protein and had the opportunity to prevent protein hydrolysis. Metagenomic analysis suggested that compared with other groups, AA had excellent biological functions including regulating obesity and insulin related microbiota. This study could provide new theoretical basis for the P. eryngii protein as a novel type of nutrient and functional component, and contribute to the development of constructing a diversified emerging food protein supply system.