Study On Preparation And Functionality Of Polysaccharides And Oligosaccharides From Eucheuma Spinosum

Eucheuma muricatum belongs to the Florida class of Gigartinales order in Solieriacea family,Eucheuma spinosum is mainly distributed in the Indonesian sea,and it is rich in polysaccharides of the Iota-carrageenan configuration.The paper takes the Indonesian Eucheuma spinosum as the research object,adopts the single factor and orthogonalexperimenttooptimizetheextractionprocessofEucheuma polysaccharides.Comparing the extraction results of different extraction methods and analyzing the stability of polysaccharides.single factor and orthogonal experiment were used to optimize the preparation technology of Eucheuma oligosaccharides.The in vitro antioxidant activity and antibacterial activity of Eucheuma polysaccharides and oligosaccharides were analyzed.Eucheuma polysaccharides and oligosaccharides were combined with?-polylysine to explore the functional changes of the complexes.Provides a theoretical basis for the application of high-valued Eucheuma spinosum and the functional study of sulfate-based polysaccharides.The results are as follows:1.The hot water extraction method and repeated freeze-thaw method for extraction of Eucheuma polysaccharides were optimized,and compared with ultrasonic-assisted extraction and alkaline extraction.The results showed that the best process of hot water extraction was extraction time of 1 h,temperature of 95?,solid-liquid ratio of 1:80,polysaccharide yield was 55.89%,polysaccharide sulfate group content was 23.50%.The optimal extraction process of repeated freeze-thaw extraction was freezing time of 2 h,thawing temperature of55?,solid-liquid ratio of 1:80,freezing and thawing 3 times,polysaccharide yield was 53.98%,polysaccharide sulfate group content was 23.76%?The ultrasonic-assisted extraction method's polysaccharide yield was 53.24%,polysaccharide sulfate group content was 21.72%;Alkali extraction method polysaccharide yield was36.62%,polysaccharide sulfate group content was 8.97%.There were no significant differences in the yields of polysaccharides and sulfate group content extracted by hot water extraction,repeated freezing and thawing and ultrasonic-assisted extraction(P>0.05),and there were significant differences in polysaccharide yields and sulfate group content by the alkaliextractionmethodcomparedwithothermethods(P<0.05).Eucheuma polysaccharides'Mn was 2.1×10~5,Mw was 6.9×10~5,Mw/Mn was 3.354.2.The Eucheuma polysaccharides have good stability at pH=7~9.At the same time,Eucheuma polysaccharides have good stability to temperature,frozen at-18?,refrigerated at 4?,normal temperature at 25?,sterilization at 85?,and sterilization at 121?,there is still good stability in the these environment,but Eucheuma polysaccharides was instability in the 135?.3.The optimization of the preparation technology of Eucheuma oligosaccharides using the total reducing power,DPPH radical scavenging ability,hydroxyl radical scavenging ability and reducing sugar content of degradation products as indexes.The best acid degradation process was degradation time of 2 h,degradation temperature of 100?,acid concentration of 0.18 mol/L.The oligosaccharides molecular weight>5000 accounted for0.78%;5000~1000 accounted for 49.72%;<1000 accounted for 49.50%,the molecular weight of oligosaccharides are greatly reduced than eucheuma polysaccharides.4.The antioxidant and antibacterial activities of Polysaccharides and Oligosaccharides from Eucheuma spinosum were studied.In terms of antioxidant capacity in vitro,the antioxidant capacity of Eucheuma oligosaccharides and oligosaccharides increased with their own concentrations.At the same concentration,the antioxidant capacity of Eucheuma oligosaccharides was greater than polysaccharides.In terms of antibacterial effects,Eucheuma polysaccharides and oligosaccharides have inhibitory effects on Escherichia coli,Staphylococcus aureus,Salmonella,Pseudomonas aeruginosa,and Pseudomonas fluorescens.The reason may be related to sulfate groups.5.The Eucheuma polysaccharides and oligosaccharides were complexed with?-polylysine respectively to study the anti-oxidation and antibacterial activities of complexes at different compound temperatures and times.In terms of in vitro antioxidant activity,the total reducing power of Eucheuma polysaccharides and?-polylysine complexes at different compounding temperatures was greater than Eucheuma polysaccharides with same concentration.At 95?,the total reducing power of the composite system increased significantly with the extension of the compounding time(P<0.05),and there was no significant difference between 60 and 25?(P>0.05).In terms of oligosaccharides,at the initial complexation time,the total reducing power of oligosaccharides and?-polylysine complex systems was lower than Eucheuma oligosaccharides with same concentration.At95?,the total reducing power of Eucheuma oligosaccharide complex system increased significantly with the prolongation of compounding time(P<0.05),and the total reducing power of Eucheuma oligosaccharides exceeding the same concentration at the later stage of compounding,and there was no significant difference between 60 and 25?(P>0.05).In terms of antibacterial effects,the bacteriostatic effect of Eucheuma polysaccharides,oligosaccharides and?-polylysine was significantly lower than?-polylysine with same concentration(P<0.05).At different compounding temperatures and times,there was no significant difference in the antibacterial activity of the composite system(P>0.05).