Studies On The Extracting Conditions And The Determination Methods Of Sulfate Content Of Fucoidan From Laminaria Residues

Fucoidan, also called fucans, is a kind of natural active polysaccharides withhigh additional values, which contains sulfate group and possesses excellentbiological properties, including anticoagulant, anti-thrombosis, anti-tumor, antivirusactivities and so on. Because it is an excellent natural resource for functional food andmedicine, it becomes a research focus among active compounds from seaweed.However, large amount of laminaria residues with fucoidan are wasted in traditionalprocessing of laminaria japonica. It is not good for comprehensive utilization ofresources, and it’s also not good for environmental protection. This study was carriedout to raise utilizations ratio of laminaria residues, and to develop another newutilization way in order to increase its additional value. Based on the extractionmethodology of fucoidan from laminaria japonica residues and determination of theproduct quality, this research made a comparison among different extraction methodson extraction efficiency of fucoidan. On the basis of single factor tests of aqueous andacid extraction, the optimum condition of extraction was obtained through orthogonaltests. And under these conditions, the pilot tests were made. Then, comparison wasmade between two sulfate group determination methods. The conclusions are asfollows.1. Aqueous, hydrochloric acid and CaCl2extraction methods could be used toextract fucoidan from laminaria japonica residues. Hydrochloric acid extractionmethod obtained the highest yield of2.45﹪, which was1.1times to water extractionmethod and3.5times to CaCl2extraction method.2. The optimum condition of aqueous extraction were obtained with theextraction temperature of70℃, the extraction time of4hours, and the ratio of solid to liquid of1:30. Under the optimal conditions, the extraction rate of fucoidan was2.40％, and the purity of crude product was17.33％by the pilot test.3. The optimal extract condition were obtained with the concentration of HCl of0.1mol/L, the ratio of solid to liquid of1:10, the extraction temperature of70℃, andthe extraction time of2hours. Under the optimal conditions, the extraction rate offucoidan was2.94％, and the purity of crude product was24.17％by the pilot test.4. No matter aqueous or acid extraction methods, the major fucoidan wasextracted in the first extracting time. In the first time, the extraction rate was95%oftotal fucoidan by aqueous extraction while91%by acid extraction. And the totalextraction rate was2.52%by aqueous extraction in two times while3.08%by acidextraction in two times.5. In the determination of sulfate content, both of barium sulfate turbidity andion-exchange chromatography method could be used. Relatively, barium sulfateturbidity method demanded simpler equipment requirement and operation, which wassuitable to be used as a simple method to determine sulfate content in generallaboratory. Compared to barium sulfate turbidity method, the ion-exchangechromatography method had a higher sensitivity and accuracy, which was suitable forprecise determination of sulfate content of samples in large numbers.