Preparation,physicochemical and structural characterizations,and bioactivities of polysaccharides from Corbicula fluminea industrial distillate

Corbicula fluminea distillate(CFD),as an industrial sub-product of the steaming process of C.fluminea,is rich in polysaccharides,proteins,and amino acids and has important developmental value.In this study,therefore,three water-soluble polysaccharides(CFDPs:CFDP-D,CFDP-U,and CFDP-T)were extracted and separated from CFD through direct ethanol precipitation,ultrasound-assisted extraction,and three-phase partitioning(TPP),respectively.Results demonstrated that the three extraction methods had important influences on extraction yields,chemical compositions,molecular weights,monosaccharide and amino acid constituents,structural characteristics,and microstructures as well as biological activities of CFDPs.Specifically,CFDP-T had higher yield(60.92%±3.58%),carbohydrate content(91.05%±1.22%),and uronic acid content(8.55%±0.18%)and lower protein content(7.15%±0.15%)than CFDP-D and CFDP-U.The three CFDPs were acidic proteoheteroglycans combined through O-glycosidic bonds and had high molecular weights of 1.93–2.41×10^(7) Da and the same monosaccharide and amino acid compositions but different contents.Compared with CFDP-D and CFDP-U,CFDP-T exhibited more excellent free radical scavenging and stimulating(1.57±0.03μM,500μg/mL)activities on RAW264.7 macrophages in vitro.Therefore,our findings suggested that CFDP-T obtained from CFD by TPP had the potential to be a functional food ingredient in food industry.