| Taro belongs to araceae,is a perennial tuber plant,rich in a variety of nutrients,and the planting area is extensive.Polysaccharides are considered as a vital active substance,with effects of antioxidant,anti-tumor,hypoglycemic,anti-fatigue and etc.This paper mainly studied the extraction,impurity removal,separation and purification,structure identification and antioxidant activity of taro polysaccharides,providing a theoretical basis for the further development,production and deep processing of taro,with certain guiding significance.The specific studies and results are as follows:(1)The extraction of taro polysaccharide by ultrasonic assisted enzymatic method was studied.Results are as follows: the best condition for cellulase 0.3%,enzymolysis temperature 50 ℃,enzymolysis time 2.5 h,enzyme solution pH 5.5,ultrasonic power 320 w,ultrasonic time of 25 min,material liquid ratio of 1:50,taro polysaccharide yield up to 23.24%.(2)Papain was used as the enzyme preparation to remove the protein in taro polysaccharide by enzymatic hydrolysis.On the basis of single factor experiment,orthogonal experiment was used to optimize the enzymatic hydrolysis conditions.The results showed the optimum process conditions for enzymatic deproteinization: papain adding amount of 4%,the enzymatic hydrolysis of 55 ℃ temperature,digestion time 1.5 h,enzyme solution pH 6,protein removal rate68.60%,polysaccharide retention rate of 98.75% and the comprehensive score of 83.66.(3)The taro polysaccharide was decolorized using the white clay reagent as the decolorizer.Studies show the best decoloring process conditions : argil content 5.8%,decoloring temperature 50 ℃,decoloring time 27.5 min.And we repeated three times under the condition of parallel experiment,confirmed real taro polysaccharide synthesis score of 92.26,the polysaccharide decolorization rate of 87.66%,while polysaccharide retention rate up to 96.98%.(4)The DEAE-52 cellulose column chromatography method was used for preliminary separation of taro crude polysaccharide,gradient elution was performed with distilled water,0.1 mol/L,0.2 mol/L and 0.3 mol/L NaCl solution respectively.The absorbance value of polysaccharides was detected by phenol-sulfuric acid method and the elution curves were finally drawn.After elution,four symmetrical elution peaks YT-1,YT-2,YT-3 and YT-4 were obtained,because of the elution peak area determines the content of polysaccharide,considering the amount of subsequent test and test feasibility of actual situation,we collect the first elution peak YT-1,enrichment,freeze drying.A symmetrical elution peak was obtained after YT-1 was chromatographed by glucan gel G-75 column and named as YT-1-a.(5)the monosaccharide components of YT-1-a were analyzed.According to the gas chromatogram,YT-1-a was mainly composed of xylose,rhamnose,mannose,galactose,glucose and galacturonic acid.According to the peak area,the mass ratios of each monosaccharide were calculated,among which the mass percentages of xylose,rhamnose,mannose,galactose,glucose and galacturonic acid were 30.785%,17.768%,10.924%,10.255%,10.196% and 7.034%,respectively.(6)The infrared spectrum analysis of YT 1-a shows that there are characteristic absorption peaks of polysaccharides in YT 1-a,which indicates that YT 1-a is a carbohydrate compound.(7)To crude polysaccharides and taro YT-1-a antioxidant activity analysis,the results showed that the crude polysaccharide taro and YT-1-a has hydroxyl free radicals,superoxide anion free radical and reducing power removal ability,with the increase of polysaccharide concentrations,radical scavenging ability increased significantly,and among them,YT-1-a cleared to hydroxyl free radicals maximum capacity can reach 93.04%,the ultra oxygen anion free radical clearance rate can reach 70.64%,reducing power up to 0.732. |
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