In vitro gastrointestinal digestion and fermentation properties of Ganoderma lucidum spore powders and their extracts

Ganoderma lucidum spores (GLS) constitute a healthy food for humans, but the hard spore shells are difficult to digest. In this study, digestive properties of GLS in different forms (sporoderm-unbroken, sporoderm-broken [SB-GLS] and sporoderm-removed [SR-GLS]) were investigated in vitro digestion and fermentation. After simulated digestion, morphologies of all three spores changed slightly. After gastric and intestinal digestion, the amounts of polysaccharides in each digestive residue of GLS, SB-GLS and SR-GLS were greatly reduced, by approximately 90.3%, 96.5% and 99.2%, respectively. Triterpenoid quantities in the digestive residues were higher than those before digestion because the absolute weight of residue decreased. Total triterpenoid contents of GLS, SB-GLS and SR-GLS after digestion were 9.2 ± 0.8, 24.7 ± 1.3, and 32.5 ± 1.1 mg/g, respectively. The amounts of CO2, CH4 and H2 found in the water and alcohol extracts of SR-GLS were similar, but the amount of H2 in the alcohol extract was higher. In terms of short-chain fatty acids (SCFAs) production, propionic, butyric and valeric acids found in the water extracts were more abundant than those in alcohol extracts, which suggests that the polysaccharides were particularly important for SCFA production. This finding indicates that SR-GLS for the water extract has stronger metabolic promotion effects and better anti-inflammatory properties.