The Separation Of Rebaudioside A And Stevioside By Three-zone Simulated Moving Bed

Steviol glycoside,currently,is a popular non-energy high-intensity sweetener,and is often used as health food and medicine because of the adjuvant therapeutic effect on diabetes,hypertension,heart disease,dental caries,and arteriosclerosis.Steviol glycosides mainly include rebaudioside A and stevioside,and highly purified rebaudioside A has a high price in current market.Nowadays,the existing methods to obtain rebaudioside A are ineffective,so in this paper,the simulated moving bed(SMB)technology is used to separate rebaudioside A and stevioside.The main contents and results are as follows:The method for determination of rebaudioside A and stevioside by high performance liquid chromatography(HPLC)is built,and then the methodology validation is carried out,and the results reveal that HPLC has a amiable effect on the determination of rebaudioside A and stevioside.The NH2 stuffing is determined as the stationary phase of the preparative column and acetonitrile/water(volume ratio of 70/30)is suitable as the mobile phase.The porosity of the preparative column is obtained by using the non-retention indicator 1,3,5-tri-tert-butylbenzene(TTBB),The adsorption equilibrium isotherms of rebaudioside A and stevioside in preparative column are measured by adsorption-desorption method.The estimation of the axial diffusion coefficient and mass transfer coefficients of rebaudioside A and stevioside is conducted by a series of empirical equations.A three-zone simulated moving bed(SMB)system with the configuration of[1,1,2]is built.The triangle theory is as a theoretical tool to design the operation conditions of SMB system.Rebaudioside A with a purity of more than 99%can be obtained in all conditions,but the purity of stevioside can only reach about 80%at the most.Comparing the experimental and simulation results,the accuracy of the measured model parameters is verified.Linear Decreasing Inertial Weight Partical Swarm Optimziation(LDIWPSO)algorithm is used to optimize the operation conditions,in the synchronous&asynchronous SMB,to separate 5g/L steviol glycoside sample with the objective of maximized feed flowrate,with the constraints that the desorbent flowrate is fixed to 2mL/min and the purities of the two products can’t be less than 99.5%.The optimized results reaveal that the performance of asynchronous SMB has a 11.4%increase,compared to which of synchronous SMB.And the experiments reveal that purities of the products in the extract and raffinate are all more than 98.9%.