Study On The Key Production Technology Of Crystalline Fructose

Fructose is the sweetest natural nutritive sweetener. Nowadays, fructose has beenwidely used in food and medicine production for its good sensory characters such as greatsweet, sweeter in lower temperature, and flavor enhancement as well as its metabolicadvantages such as insulin-independence and low glycemic effect. This paper took thecorn starch as raw material. Different kinds of enzyme for the liquefieation, thesaccharifieation and the isomerization of starch been used. During the production ofcrystalline fructose, there are some key problems to be resolved, including isomerizationof glucose syrup, separation of fructose and glucose and crystallization of fructose. Thesekey technique problems during crystalline fructose production were investigated in thisthesis.（1） The influences of activation conditions on the enzyme activity ofGENSWEET^TMIGI-SA immobilized glucose isomerase were studied from concentrationof glucose syrup, temperature, pH, activation time and metal ions. The optimal activationcondition was: glucose syrup60%,55°C, pH7.5and activation time4h. Under thiscondition above, the enzyme activity of immobilized glucose isomerase was815U/g,which was higher40%than one under normal activation condition. Mg²⁺、Co²⁺、Mn²⁺andZn²⁺were not necessary to be added into glucose syrup when immobilized glucoseisomerase was activated.（2） This experimental studied using the enzyme column producted fructose syrupcontinuously. The best technological conditions of isomerization for the glucose syrupwere ascertained. The best technological conditions of single factor experiments were: theheight-diameter of the reactor13.85, the glucose syrup concentration50%, the flowvelocity1.18mL/min, Zn²⁺. Through the orthogonal expenments, the best technologicalconditions were: the height-diameter of the reactor20.83, the glucose syrup concentration50%, the flow velocity0.8mL/min. Through the best technological condition fructoseglucose syrup with fructose concentration48.5%was obtained.（3） Using dynamic screening, a Ca type resin with the best separation ability wasselected from others. The influences of the height-diameter of the column, temperature,feed volume and washing rate on the separation of fructose and glucose were investigated.The optimal separation conditions were: the height-diameter of the column15, columntemperature50°C, feed volume2mL, washing rate2mL/min. And adding of Mg²⁺、Mn²⁺ and Zn²⁺can improve their separation.（4） This experiment used the water extraction crystallization fructose. Used singlefactor experiment to study the influence of fructose crystallization with syrup purity, syrupdensity, temperature, the amount of seeds and crystallization time. And the besttechnological conditions of single factor experiments were: the syrup purity98%, thesyrup density85%, crystallization temperature40°C, the amount of seeds5%,crystallization time30h. However, the fructose yield was lower and needed to beimproved.