Two‐Phase Extraction, Structural Characterization of the Polysaccharide from Raspberry Pomace and Its Protection Effects against Erythrocyte Hemolysis

Abstract

In present study, a new polysaccharide (RPP) from raspberry pomace is prepared through ultrasound‐assisted aqueous two‐phase extraction (UAATPE) and purification using two‐step column chromatography, the extraction conditions are optimized by response surface method (RSM). Under the optimal parameters: liquid to material ratio of 80 mL g−1, ultrasonic power of 340 W, and ultrasonic time of 39 min, the yield of the polysaccharides is 11.72 ± 0.05%. RPP with average molecular weight (Mw) of 59 300 Da is composed of six monosaccharides. Nuclear magnetic resonance (NMR) analyses confirmed that RPP contains six main glycosidic linkages including α‐l‐Araf‐(1→, →2)‐α‐l‐Rhap‐(1→, →4)‐β‐d‐Manp‐(1→, →4)‐α‐d‐GalAp‐(1→, →3)‐β‐d‐Galp‐(1→, →4)‐β‐d‐Glcp‐(1→. RPP exhibits remarkable protective effects against H2O2‐induced erythrocyte hemolysis, the generations of reactive oxygen species, and malondialdehyde are inhibited, and the activities of glutathione peroxidase and catalase are effectively enhanced. The current findings proved that UAATPE is an effective method to extract the polysaccharide from raspberry pomace and provides a new idea for the utilization of nutrient‐rich raspberry fruit residue.