The Solution Properties Of Polysaccharide From Ulva Fasciata

Ulva fasciata is a kind of abundant green alga resources.Ulva fasciata polysaccharides?UFP?is a gelling polysaccharide.This paper firstly analyzed the its physic-chemical properties,then studied factors on its static rheological properties,finally discussed the solution properties of UFP'S dilute domain,and further researched influence of adding salt on the salt tolerance of UFP and its molecular chains stiffness.The main contents and results are as following:Hot water extraction was used to extract crude polysaccharide from Ulva fasciata.The main constituent of Ulva fasciata were determined.It was suggested UFP existed in the form of sulfuric acid ester.Gas chromatography-mass spectrometry showed UFP was composed of rhamnose,fucose,arabinose,xylose and glucose.Analysis showed that UFP was an acidic heteropolysaccharide.Rheological properties of UFP were investigated,it was found that UFP's thixotropy was not significantly.When frequency ranged from 0.1Hz to 1 Hz,the storage modulus G'and loss modulus G"showed obvious frequency dependency.The results also showed that when gel time was 4h,gel strength was improved to maximum value of 681 g·cm^-2.Besides,KCl played a more important role than NaCl on gel strength at same concentration,adding KCl had a maximum value of 1920 g·cm^-2?Influence of concentration,temperature,p H and salts on static rheological properties of UFP were investigated.The results showed that when shear rate range from 500 s^-11 to 4000.0 s^-1,apparent viscosity exhibited shear thickening behavior following the power law model.Its apparent viscosities were affected by its gum concentration greatly and changed slightly by the temperature 10⁵0?and pH 5¹0.UFP was not sensitive to the presence of NaCl,while CaCl₂ concentration can significantly affect the apparent viscosity.Ubbelohde viscosity method for a series of UFP dilution solution were carried on the detailed characterization of molecular aggregation,it was assumed that the polysaccharide molecular chain of UFP solution characterized with semiflexible,and it was found that UFP had a better salt tolerating ability in K⁺solution than in Na⁺solution,and a better salt tolerating ability in Ca²⁺solution than in Mg²⁺solution.