Glycogen-like α-Glucan from Morchella sextelata : Conserved Core Structure and Conformational Characteristics across Geographical Origins

Abstract Morchella spp., a kind of prized edible mushrooms, is widely cultivated and consumed in China. The α-(1 → 4)-glucans have been identified as one of their major polysaccharides, yet the classification of these glucans as glycogen analogs remains ambiguous and restricts subsequent research. This study aimed to comprehensively characterize glycogen-like α-glucans (30-fractions) isolated from Morchella sextelata across five geographical origins and evaluated structural variations. The α-glucans shared a conserved α-(1 → 4)-backbone, which was confirmed by HILIC–UHPLC–ESI––MS/MS fingerprinting and NMR spectra. TEM revealed typical glycogen α-particles (125–185 nm) and β-particles, further supported by Raman spectra combined with PCA. While SEC-MALLS revealed geographically varied Mw (1141.0–2174.0 × 104 g/mol), their core structures appeared to be highly conserved. They consistently showed near-spherical conformation, low-viscosity, and shear-thinning rheological behavior. This systematic structural identification confirms the glycogen-like nature of the target glucan and provides fundamental structural support for its potential exploitation in functional foods and nanodelivery systems.