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

Pleurotus eryngii (P. eryngii) protein is considered a high-quality protein because it is rich in essential amino acids and displays multiple significant functional characterizations that vary with its fabrication processes. We aimed to investigate the differences in P. eryngii protein extracted via 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 (S) in terms of gastrointestinal digestion and fecal fermentation consequences. Protein hydrolysis and structural analysis were performed after in vitro gastrointestinal digestion, and it was found that AA showed the highest hydrolysis degree, whereas CAA showed the lowest. The results of fluorescence chromatography and infrared chromatography indicated that the reasons for the digestion difference might be the unfolding degrees of the protein tertiary structure and polysaccharide content, which is the major component of crude proteins and can 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 a new theoretical basis for the P. eryngii protein as a novel type of nutritional and functional component and contributes to the development of a diversified emerging food protein supply system.