Structural characteristics, biological, rheological and thermal properties of the polysaccharide and the degraded polysaccharide from raspberry fruits

A native polysaccharide (RCPI) with sugar content of 79.94 ± 0.57% was isolated from raspberry fruits. A degraded polysaccharide (DRCPI) with sugar content of 83.82 ± 0.71% was obtained from the crude polysaccharides after degradation by Fe2+-H2O2 treatment. The molecular weights of RCPI and DRCPI were determined to be 411,000 and 8010 Da, respectively. GC analysis revealed that both RCPI and DRCPI were composed of the same monosaccharides (rhamnose, arabinose, xylose, mannose, glucose, galactose, and galacturonic acid) in different molar ratios. IR and NMR spectroscopy confirmed that RCPI and DRCPI possessed similar structural characteristics, although DRCPI displayed higher antioxidant activities and greater thermal stability. Furthermore, DRCPI exhibited excellent rheological properties. These data provide evidence to support the application of raspberry-derived polysaccharides in functional foods.