Process Study On Fructose Purification From High Fructose Corn Syrup

Fructose,a simple sweetener with healthy functions,is widely used in the food and pharmaceutical industries.It is physically and functionally distinct from other sugars in the relative sweetness,unique sweetness,solubility,hygroscopicity,osmotic pressure and so on.Importantly,it features post-prandial blood glucose lowering ability.Moreover,in pharmaceutical industry,fructose can be made into injection due to its metabolic characteristics and osmotic pressure characteristics.Fructose can be used in the treatment of diabetes,liver disease,cardiovascular disease and brain diseases.Hence,the demand of crystalline fructose has been increased in the pharmaceutical industry.In chemical industry,fructose is an important raw material and intermediate with great potential in the manufacture of HMF(5-hydroxymethylfurfural)and other platforms compounds.In china the crystalline fructose mainly depend on foreign imports,and the study on crystalline fructose production is not sufficient,including the HFCS separation process and the crystallization process of fructose.These two aspects of problem were investigated in this thesis.First,among 14 calcium ion form of strong acid cation exchangers tested,cation exchanger XA 2004/22 displayed the best adsorption performances for fructose,with adsorption ratio of fructose to glucose reaching 2.32 at 303 K.Study on the effect of 11 kinds of cations on fructose and glucose adsorbed on the resin,Ca2+ is preferential.Linear model can fit the static equilibrium adsorption data well.The adsorption kinetic followed the pseudo-second order model,and according to Intra-particle diffusion model the adsorption rate was controlled by the liquid film diffusion resistance and pore diffusion resistance.Secondly,the effect of fixed bed column width,inlet concentration and inlet velocity on packed bed filled with Ca2+-immobilized cation exchanger XA 2004/22 has been studied.The preferred conditions of the dynamic adsorption process are high concentration of fructose,low velocity and narrow width of packing layer.In a conclusion,both the Yoon-Nelson and Thomas models can be used to predict adsorption performance for fructose in a fixed-bed column.Under the optimized column chromatography conditions,fructose was obtained in a 24.3%(w·w-1)recovery and 92.4%(w·w-1)purity by employing a two consecutive chromatographic process.Finally,through comparison of fructose crystals produced by using three different crystallization methods,cooling crystallization method was chosen to prepare crystalline fructose in the ethanol-water solution at volumetric rate VEt OH : VH2 O of 7.5.The solubility and super-solubility of fructose in different solvent systems was determined.From the study on the metastable zone,it has been found that the stirring speed and seed dosage influence the metastable zone width.Via optimization on crystallization conditions,we successfully established an new cooling crystallization process for fructose,yielding crystalline fructose with larger particle size,good crystal shape and narrow particle size distribution(300~600μm)of the fructose,purity over 99%,recovery 59.3wt%.However,it suffered relatively low total fructose recovery,and further work to raise recovery is required.