Deep eutectic solvent-based extraction of bioactive polysaccharides from oilseed pumpkin and valorization of extraction residues

Producing useful products from waste treatment is driven by the need to unlock the value in waste. In this study, a deep eutectic solvent (DES) extraction method was developed to obtain polysaccharides from oilseed pumpkin flesh. A purified fraction, designated PPOP-3, was achieved through ion-exchange and gel-filtration chromatography. Physicochemical and biological characteristics of the purified polysaccharides, such as monosaccharide composition, molecular weight, glycosidic linkage patterns, and antioxidant activity were systematically characterized. Furthermore, the residues remaining after polysaccharide extraction were converted into magnetic biochar (PMB). The morphology, pore structure, and surface chemistry of PMB were analyzed and its performance in the refining process of pumpkinseed oil to adsorb carotenoids was evaluated. This work not only delivers fresh understanding of the structural features of oilseed pumpkin polysaccharides but also presents an integrated, sustainable approach for agricultural by-product valorization. • Polysaccharides from oilseed pumpkin flesh were extracted efficiently with DES. • Primary structure of purified polysaccharide was elucidated. • Residues after polysaccharide extraction were converted into PMB. • PMB performed well in the refining process of pumpkinseed oil.