Study On The Extraction,purification And Properties Of Quinoa Polysaccharide

Compared with animal polysaccharides,plant polysaccharides have higher content and easier separation and purification,so plant polysaccharides have become a research hotspot in recent years.Plant polysaccharides have many biological activities and less toxicity,so they have good application prospects.In this study,quinoa was used as raw material,ultrasonic assisted extraction method was used,ultrasonic time,ratio of liquid to material and ultrasonic temperature were used as single factor design experiments,and the yield was used as evaluation index to carry out three factor and three level Box Behnken center combination experiment design,so as to optimize the extraction conditions of quinoa polysaccharide.Then,AB-8 macroporous resin adsorption,DEAE cellulose column separation,Sephadex G-100 dextran gel column were further purified to obtain the homogeneous quinoa polysaccharides.The structures of quinoa polysaccharides were characterized by X ray diffractometer(XRD),infrared spectroscopy(FT-IR),nano laser particle size analyzer,Congo red test,nuclear magnetic resonance spectroscopy(1H-NMR)and(13C-NMR)and scanning electron microscope(SEM).Quinoa polysaccharides were analyzed by gas chromatography and rheometer.Finally,the effect of quinoa polysaccharide on yoghurt beverage was analyzed.The main results are as follows:(1)Extraction and response surface optimization of quinoa polysaccharide.In the single factor experiment,the three factors had great influence on the yield of quinoa polysaccharide.At the same time,through the multi factor interaction experiment,it could be concluded that there were significant interaction between ultrasonic time and liquid material ratio,ultrasonic time and ultrasonic temperature,liquid material ratio and ultrasonic temperature.Then,in response surface optimization experiment,the optimal extraction conditions of quinoa polysaccharide were determined as follows:ultrasonic time 51 min,liquid material ratio 21 ml:g,ultrasonic temperature 60?.Under these conditions,the yield of quinoa polysaccharide was 3.62%.(2)Effect of separation and purification on the structural characteristics of quinoa polysaccharide.Ultrasonic assisted extraction,AB-8 macroporous resin adsorption,DEAE cellulose separation and Sephadex G-100 gel column purification were used to obtain QP,QP I,QPI-I and QPI-I-I from quinoa respectively.After separation and purification,the infrared absorption peak intensity,1H-NMR and 13C-NMR diffraction intensity,particle size,dispersion index and SEM surface structure all showed a decreasing trend,indicating that the separation and purification destroyed the intermolecular hydrogen bond or van der Waals force,resulting in the weakening of intermolecular interaction.The XRD and Congo red experiments showed that the separation and purification was conducive to the formation of crystal structure and triple helix structure.The results showed that after purification,quinoa polysaccharide had better stability and smaller particle size difference,the lamellar structure became smaller,the cross-linking effect weakened,and the surface viscosity decreased.Therefore,the structural characteristics of quinoa polysaccharide were changed by separation and purification.(3)Monosaccharide composition analysis of QPI-I-I.The standard monosaccharide,mixed monosaccharide and QPI-I-I hydrolyzed polysaccharide were derivatized with acetonitrile acetate,which could be analyzed by gas chromatography.The monosaccharide composition of QPI-I-I was quantitatively analyzed by internal standard method.It could be concluded that QPI-I-I contains six kinds of monosaccharides:arabinose 0.46%,rhamnose 0.70%,xylose 0.69%,mannose 1.07%,galactose 2.00%and glucose 21.09%,and the molar ratio was:arabinose:rhamnose:xylose:mannose:galactose:glucose=0.61:0.85:0.92:1.19:2.22:23.41.The results showed that QPI-I-I contained more glucose and less arabinose.(4)Rheological properties and application in yoghurt beverage of QP.QP solution showed the typical characteristics of non-Newtonian pseudoplastic fluid and had good thermal stability.In acidic or alkaline environment,the viscosity of QP solution was reduced.The addition of Na+ had little effect on the viscosity of the QP polysaccharide solution,while the addition of Ca2+ increased the viscosity of the QP polysaccharide solution.In the whole experiment,elasticity and rigidity played an important role in the polysaccharide QP solution.In the yoghurt drink,the best condition of single adding QP was:QP concentration 0.40%,pH=4,at this time,the stability was the best,the sedimentation rate of fermented and blended milk drinks were 10.76%and 12.08%,respectively,which showed that the experimental effect of adding QP was slightly worse than that of pectin,CMC,carrageenan,guar gum,but better than that of blank sample without stabilizer.In the compound experiment,the best compounding scheme was not the same in the mixed yoghurt beverage and fermented yoghurt beverage.In the mixed yoghurt beverage,the best scheme of this experiment was:quinoa polysaccharide QP+CMC:0.08%+0.40%,precipitation rate was 6.88%.In the fermented acidic milk drink,the best scheme of this experiment was:quinoa polysaccharide QP+pectin:0.24%+0.24%,the sedimentation rate was 6.00%.