Application Of Membrane Separation Technology In The Production Of Starch Sugar

Modern membrane separation process has the following advantages: no phase change,low power consumption, easy operation, easy control and high degree of automation. It hasa high development value to use it in the production of starch sugar. In this paper, acomprehensive study on the classification, purification and concentration effects ofmembrane separation technology in the production of starch sugar was made.First of all, two ultrafiltration membranes with MWCO10000Da and MWCO1000Daassociated were used to classify the maltodextrin MD6(DE=9.92), which was producedfrom starch by α-amylase. Five products of were prepared. They were MD1(DE=1.91),MD2(DE=7.96), MD3(DE=29.74), MD4(DE=2.87), MD5(DE=13.80). The change oftheir composition and structure was also studied. It showed that, molecular weightdistribution of the classified maltodextrin became narrow. Average molecular weight of themaltodextrins was: MD1＞MD4＞MD2＞MD6＞MD5＞MD3. Content ofoligosaccharides in them was: MD3＞MD5＞MD6＞MD2＞MD4＞MD1. Themicroscopic structure, crystalline structure and thermal stability of maltodextrin had largechanges. As with the molecular weight increased, the surface of the microscopic structure ofmaltodextrin tended to smooth, the degree of crystallization decreased and thermal stabilityincreased. Their properties of water-soluble, transparency, viscosity, moisture absortion,freeze-thaw stability and gel formation were studied. It indicated that there are largedifferences in their properties after classification, which is closely related to the compositionand molecular weight distribution of the maltodextrins.Secondly, studied on the removal of monosaccharide from isomaltooligosaccharides bynanofiltration, used a MWCO150-300Da membrane. The influence of nanofiltrationconditions on permeation flux and components of isomaltooligosaccharides was researched.And the optimum conditions were as follows: temperature25-30℃, operated pressure0.7MPa and feed mass fraction10%. When the purification fold was10, monosaccharideremoval rate was up to98.73%.At last, studied on the concentration of potato residue α-amylase hydrolyzate by reverse osmosis, used a MWCO50-100Da membrane. The cleaning effect of differentconditions on the membrane was also studied. The optimum operating conditions wereobtained as follows: temperature30℃, pressure0.6-0.7MPa and flow velocity30mL/min.Under these conditions, the hydrolyzate was concentrated from5°Bx up to19.5°Bx. Afterconcentration, water was reduced by78.62%. And the best cleaning condition was: thesolution mixed with0.2%NaOH and0.2%sodium dodecylbdenzenesulfonate, which wasused at40℃. And the coefficient of restitution reached96%.