Preparation Of Stevioside Surface Imprinting Material And Its Recognition And Selection Properties

As a kind of low-calorie high-sweetness sugar,stevioside has more and more development space in food and medicine,which largely meet people's needs in the rich material life.The main purpose of this paper is to prepare a functional material that has the ability to recognize and select stevioside to improve the extraction purity of stevioside.The main content of the invention is that the macroporous adsorption of polystyrene primary amine microspheres(PSA)is used as an adsorbent material,and stevia sugar is used as a template molecule.Steroids are prepared by means of distributed graft polymerization and simultaneous graft polymerization.The molecularly imprinted sugar material and the specific adsorption properties of the imprinted material on stevia can be used to provide important reference data for the purification of stevioside.First,the raw material PSA was soaked in N,N-dimethylformamide(DMF)so that the amino group on the PSA surface was activated to facilitate subsequent graft polymerization.Then the surface of the PSA was grafted onto the surface of the PSA by radical-initiated graft polymerization via free radicals to prepare grafted microparticles PMAA/PSA.The grafted polymer PMAA/PSA was characterized by infrared spectroscopy and thermogravimetric analysis,and the single factor conditions such as solvent,temperature,amount of monomer initiator,reaction time,etc.were studied in the preparation process.Influencing,utilizing thebasic characteristics of amino groups,using the titration method to detect the grafting rate of MAA,and using the hydrogen bonds on the grafted polymer PMAA/PSA chain and the electrostatic interaction between the ester groups on the stevioside molecule to achieve PMAA/ Adsorption of stevia on PSA,through the exploration of various conditions in the adsorption process,investigated the optimal adsorption conditions between polymer PMAA/PSA and stevioside molecules.The experimental results show that: when the ethanol solvent 50 ml,the monomer MAA 1.4ml(mass fraction is 2.66% of the total solution),the monomer ammonium persulfate 0.0274(accounting for 2% of the monomer mass fraction),the grafting temperature 40°C,reaction time At 8h,functional grafted particles with a grafting degree of 601.8 mg/g were obtained;at a temperature of 20°C,the adsorption time was up to3 h,and the adsorption of stevioside by PSA/PMAA reached a maximum of 52.56mg/g at pH=6.The steviol surface imprinted polymeric material MIP-PMAA was prepared by the surface imprinting of stevioside from the prepared PMAA/PSA with stevioside molecule as the template and ethylene glycol diglycidyl ether(EGDE)as the cross-linking agent./PSA.The dynamic and static two methods were used to study the specific binding ability of MIP-PMAA/PSA to stevioside molecule.Glucose was used as a control and the template,cross-linking agent,reaction time and other conditions were explored during the preparation.And the effect of each condition on the splitting performance of the MIP-PMAA/PSA during the splitting process.The experimental results showed that the stevia was prepared using a stevioside ethanol solution with a concentration of 1 g/L as the solvent at a reaction temperature of 40 °C,a reaction time of 6 h,and a crosslinker EGDE mass fraction of0.238 %(0.1 mL).The molecular weight of molecularly imprinted material was the best,the selectivity coefficient was 7.88;the maximum adsorption capacity of static adsorption was51.72 mg/g,and the dynamic adsorption capacity was 50.27 mg/g.In addition,various materials and methods used in the “Distribution Method” were usedto prepare “MIP-PMAA/PSA”,a molecularly imprinted material on the surface of stevia,using the “simultaneous method”.Each single factor in the preparation process was also investigated for MIP-PMAA/PSA.The effect of resolution ability was compared,and the size of the resolution ability of the imprinted polymer was compared with that of the stepwise method.The experimental results show that in the simultaneous blot method: When the ratio of the crosslinker EGDE and monomer MAA mass ratio is 2:7 and the ratio of the mass of stevia to monomer MAA is 4:1,the separation performance is highest.Stevioside has a selectivity coefficient of 5.92.Compared with the distributed preparation method,the selective adsorption effect of the stepwise method is better than that of the synchronous method,whether it is static selective adsorption or dynamic selective adsorption.However,the difference is not great.However,the preparation process using the synchronization method is simple.Therefore,it is recommended to use the synchronization method in the process of production.