Linking structure to solubility-related properties: Comprehensive characterization of polysaccharides from...

Chaenomeles speciosa (Sweet) Nakai polysaccharides (CSP) have long been recognized for their nutritional and medicinal values. In this study, four homogeneous polysaccharides were obtained from C. speciosa fruits, including one neutral arabinan (CSP-1-2) and three acidic polysaccharides with distinct structural features: a highly branched rhamnogalacturonan-I (RG-I) pectin (CSP-1-1), a linear highly methylesterified homogalacturonan (HG) (CSP-2-1), and an arabinogalactan-type pectin (CSP-3-1). The structural feature of CSP-2-1 are related to its low solubility, as further supported by Fourier-Transform Infrared (FTIR) spectroscopy, Scanning Electron Microscopy (SEM), and Atomic Force Microscopy (AFM). SEM showed a dense, non-porous dry morphology, while AFM revealed the formation of compact nano-aggregates in aqueous solution. These findings provide a structural basis for understanding the solution behavior and aggregation mechanism of this pectic polysaccharide, which may be relevant for designing hydrocolloid systems.