The Studies On The Utilization Of Alginate Which Is By-produced From Laminaria Japonica

Alginate has been widely used as a natural macromolecule material.It isthe unique biologicalpolysaccharide in brown algae.In this article, Sodium alginate was extracted by using alkaliextraction from the by-productsof Laminaria Japonica processing.The extraction technologywas optimized when crude yield and content of alginate taken as indicators through orthogonaltest.The crude sodium alginate EA and the parts obtained by low concentration of ethanolprecipitation was further purified by D301-T weak-base exchange anion resin and four fractionswere obtained.The four fractions molecular weights were estimated by Sephacryl S-300gelchromatography,and their structural characteristicswere analyzedby IR spectrum and HPLC.Theresults and conclusions were as follows:1、 The contents of moisture,ash,protein and fat in Laminaria Japonica were93.9%,11.86%,8.70%and0.2%respectively. An orthogonal test was designed to evaluate the optimumfactors. The results by orthogonal test showed that the optimum extraction condition was asfollows: extraction time of4.5hours,ratio of solid to liquid of1:40, Na2CO3concentration of3.5%and extraction temperatureof70℃.The crude yield of sodium alginate Aextracted was44.07%with the content of80.99%2、 The D301-T weak-base exchange anion resin was comfrimed to be the best resin for theseparation and purification of the crude product EA and Aillustrated by the static adsorptionand dynamic elution experiments. The separation parameters of D301-T weak-base exchangeanion resin were determined as: pH of7.5, velocity of flow of1.0mL/min, NaClconcentration of0-2.5mol/L. Four fractions, AF1、AF2、EF1andEF2were obtained with therecovery yields of19.33%、63.33%、9.69%and70.00%,and sodium alginate content of84.56%、89.69%、77.38%and83.59%, respectively. AF1、AF2、EF1and EF2were furtherseparated by Sephacryl S-300gel chromatography and the molecular weights of AF1、AF2、EF1and EF2were estimated as257KD、81KD、175.7KD and38.08KD respectively.3、 The structural characteristics of the four fractions were analyzedby IR spectrum andHPLC.The results of IR spectrum indicated that absorption peaks of815cm-1weresignificantly higher than the787cm-1.And the absorption peak of787cm-1in EF1and EF2were almost invisible.So we inferred that the four components are high mannuronic acidcomponent. After HPLC analysis, the results showed the four components are highmannuronic acid component.