Quality characteristics of Cornus officinalis Sieb. et Zucc. polysaccharides extracted by different methods

【Objective】The effects of different extraction methods on the quality characteristics of Cornus officinalis Sieb. et Zucc. polysaccharides were studied to provide reference for the deep processing and development and utilization of C. officinalis polysaccharides.【Method】Six methods were used to extract C. officinalis polysaccharides，including hot water extraction，microwave-assisted extraction，ultrasonic-assisted extraction，acid extraction，alkaline extraction and composite enzyme extraction，and the effects of the different extraction methods on the yields of C. officinalis polysaccharides，the contents of total sugars，antioxidant capacity，physicochemical properties，and structural characterization of C. officinalis polysaccharides were compared.【Result】The quality characteristics of C. officinalis polysaccharides obtained by different extraction methods were different. The extraction rate（15.13%）total sugar content（93.43%），ferric ion reducing ability（1.31 mmol/g），and C=O and C-H contents in polysaccharides obtained by alkaline extraction method were higher than those obtained by other methods；the oil absorption（19.00 mL/g）and foam stability（41.67%）of C. officinalis polysaccharides extracted by microwave-assisted extraction were higher than those obtained by other methods；the cholesterol adsorption capacity（621.80 mg/g）of the polysaccharides extracted by composite enzyme extraction method was the strongest，and the scavenging rate of 1,1-diphenyl-2-trinitrophenylhydrazine（DPPH）radical（60.06%）was greatly higher than that of the other methods；when the mass concentration of C. officinalis polysaccharide extracted by hot water extraction was 0.2 mg/mL，the scavenging rate of 2, 2-azino-bis（3-ethylbenzothiazoline-6-sulfonic acid）diammonium salt（ABTS）free radical（61.20%）was greatly higher than that of other methods. The foaming ability of polysaccharides extracted by ultrasonic-assisted extraction（17.00%）was significantly higher than that of other methods（P<0.05）. In addition，Fourier transform infrared spectroscopy showed that the contents of functional groups in C. officinalis polysaccharides extracted by different methods were different；scanning electron microscopy analysis showed that the surface of C. officinalis polysaccharides extracted by hot water extraction and microwave-assisted extraction were smooth and flat， and the structure of the extracted polysaccharides was tightly aligned；C. officinalis polysaccharides by ultrasonic-assisted extraction and composite enzyme extraction had a strong intermolecular repulsive force；X-ray diffraction suggested that there were obvious and strong absorption peaks at 32º and 45º for C. officinalis polysaccharides extracted by alkaline extraction method，while those extracted by hot water extraction method，microwave-assisted extraction method，ultrasonicassisted extraction method，acid extraction method and composite enzyme extraction method had a similar structure；in the thermal stability analysis，the thermal stability of C. officinalis polysaccharides extracted by alkali extraction method was higher than that of other methods，and the mass loss was about 50.2% at 800 ℃.【Conclusion】The structure，antioxidant activity and physicochemical properties of C. officinalis polysaccharides extracted by various methods are different， but different methods have slight effect on their thermodynamic characteristics，showing a similar trend. It can be developed and applied according to the characteristics of polysaccharides extracted by different methods.