Extraction,Separation And Purification Of Polysaccharides From Northeast Dandelion Leaves And Its Application In Beverages

As a medicinal and edible homologous plant,dandelion has antioxidant,hypoglycemic,anticancer,antibacterial and other effects,and is widely used in food,medicine,daily chemical industry and other fields.In this paper,the leaves of Northeast dandelion were systematically studied,including the extraction,separation and purification,basic components,physical and chemical properties,structure and biological activity analysis of polysaccharides,and a dandelion leaf polysaccharide beverage was prepared.The main research contents are as follows:(1)Extraction of polysaccharides from Northeast dandelion leaves.Taking the yield of polysaccharide as the investigation index,the polysaccharide in the leaves of Northeast dandelion was extracted by ultrasonic-assisted compound enzyme method.Through single factor experiment and response surface analysis,the optimal extraction conditions were obtained as follows:cellulase 1.9%,pectinase 0.2%,papain 0.3%,ultrasonic time 80 min,enzymatic hydrolysis temperature 50°C,p H 6.The yield of lower polysaccharide was(18.25±0.21)%.(2)Separation and purification of dandelion leaf polysaccharide.Based on the decolorization rate and polysaccharide loss rate,S-8 was selected from macroporous resins D101,D303,ADS-7,and S-8 for decolorization;,in the hydrogen peroxide method,the activated carbon method is preferred for decolorization,and the decolorization rate is(76.36±2.65)%,and the polysaccharide loss rate is(28.6±1.18)%;then use DEAE-52 ion exchange column chromatography to decolorize crude polysaccharide DLP.Fractionation,the basic components,physicochemical properties,ultraviolet spectra,infrared spectra and microstructures of the samples DLP,DLP-1,and DLP-2 before and after purification were analyzed.DLP-2,the yields were58.34%and 21.96%,respectively.The total sugar content of DLP-1 was the highest among the three sugar samples,reaching(76.21±1.52)%;the uronic acid content of DLP-2 was the highest,reaching(41.78±1.24)%;DLP,DLP-1,DLP-The protein content in 2 was less than 8%;the color test determined that the sample did not contain starch,polyphenols and reducing sugars,and the sulfuric acid-carbazole reaction determined that DLP-1 was a neutral polysaccharide,and DLP-2 was an acidic polysaccharide;infrared Spectral analysis verified that all three had obvious polysaccharide characteristic peaks.(3)Biological activity studies of dandelion leaf polysaccharides.The antioxidant activity and in vitro hypoglycemic activity of DLP,DLP-1 and DLP-2 fractions before and after purification were analyzed.The results showed that when the concentration of the tested sample was 2.0 mg/mL,the ABTS~+·clearance rates of DLP,DLP-1 and DLP-2 components were 62.36%,95.82%and 39.14%,respectively,and the·OH clearance rates were 98.11%,respectively,95.2%,93.55%,and the reducing powers were 1.486,0.612,and 1.522,respectively.When the concentration of the tested sample was 0.5 mg/mL,the DPPH·clearance rate of DLP-1 was 55.1%,while the DPPH·clearance rate of DLP and DLP-2 was infinitely close to 100%.When the concentration of the tested sample was 2.0 mg/mL,the inhibition rates of DLP and DLP-1 onα-glucosidase were 65.69%and 88.07%,respectively,while DLP-2 had no obvious inhibitory ability onα-glucosidase.(4)Preparation of dandelion leaf polysaccharide beverage.The purified dandelion leaf polysaccharide was used as the main raw material to prepare the polysaccharide beverage.Taking the sensory score as the inspection index,the optimal extraction process of dandelion leaves was optimized by single factor and orthogonal experiment as follows:the ratio of solid to liquid is 1:30 g/mL,the extraction temperature is 70°C,and the extraction time is 30 min;C-Nose electronic nose analysis,get the best beverage formula:dandelion leaf extract 60%,dandelion polysaccharide liquid 25%,citric acid 0.02%,steviol glycoside 0.008%,sodium carboxymethyl cellulose as product stabilizer;clear free The basic test results showed that the ABTS~+·clearance rate,·OH·clearance rate and DPPH·clearance rate of dandelion leaf polysaccharide beverage were 88.35%,42.9%and 84.72%,respectively.It can be seen that the dandelion leaf polysaccharide beverage is a beverage product with certain antioxidant activity.