Unlocking sustainable protein from Pleurotus eryngii: Enzymatic degradation of cell wall enhances digestibility in mycelia and fruiting bodies

From the paper

Abstract

The bioavailability of fungal protein is constrained by the resilient chitin-based cell wall. This study aimed to enhance the digestibility of Pleurotus eryngii protein—from both fruiting bodies and mycelia—through enzymatic cell wall disruption using lywallzyme I, lywallzyme II, and snailase. The digestive process was monitored by laser diffraction analysis and fluorescence microscopy, while released amino acids and peptides were characterized by UHPLC–MS/MS and NanoLC–MS/MS. Enzymatic pretreatments effectively increased protein accessibility. Mycelia exhibited higher digestibility than fruiting bodies, with more uniform particle dispersion and greater peptide yields. Peaked digestibility was achieved using lywallzyme II or snailase for mycelia, and lywallzyme II for fruiting bodies. Following simulated digestion, total amino acid content reached 28 mmol/L, dominated by L-lysine, L-alanine, and L-tyrosine. The number of released peptides reached 28,028 in mycelia pretreated with 40 mg/g lywallzyme II. Crucially, low molecular weight peptides (≤800 Da) dominated the profile, constituting up to 71 % of the total pool. Furthermore, the digested products formed nanoscale colloidal complexes with negative surface charge, indicating increased bioavailability. Collectively, these findings indicate that targeted cell wall degradation is an effective strategy for unlocking the nutritional potential of fungal proteins.