Extraction, Purification And Characterization Of Ploysaccharides From Clam(ruditapes Philippinarum) Cooking Liquid

China is one of the biggest countries of shellfish farming, processing and consuming. The yield of shellfish makes up 80% of total mariculture production, it is an important part of the marine aquaculture industry. Clam cooking liquid is the by-products of clam processing. A lot of the cooking liquid is directly poured into sea, which would result in the waste of resources and pollution. In the paper, clam cooking liquid as raw material was concentrated by the different temperature rotary evaporation concentrated manner, the polysaccharide in which extracted using alcohol precipitation after acid precipitation and direct alcohol precipitation method. Then the products were purified by DEAE-Sepharose Fast Flow anion exchange chromatography, getting two components, the compositions of monosaccharide were measured by high-performance liquid chromatography.Conclusions as follows:1. The content of soluble solids in the clam cooking liquid was 1.6%, and the contents of protein and polysaccharide were 0.57% and 0.74% respectively. The polysaccharide accounted for 46.3% of soluble solids.2. Clam cooking liquid was hydrolyzed by papain and Alcalase. When the pH and reaction temperature were certain, with the amount of enzyme(2.5%, 5%, 10%, 20%) increased and hydrolysis time(1h, 2h, 4h, 6h) extension, polysaccharide contents of digested by papain enzyme hydrolysis were similar with the undigested, indicating that the enzyme had no obvious effect on increasing the content of polysaccharide in clam cooking liquid.3. In different temperature concentrated manner, the cooking liquid using alcohol precipitation after acid precipitation could significantly increase the amount of extraction of crude polysaccharide, compared with the original cooking liquid extraction amount, containing a respective increase of 11.1% and 14.1%; the amount of extraction of crude polysaccharide increased 10.2% and 5.4% by direct alcohol precipitation method. The extraction method of crude polysaccharide by acid precipitation, alcohol precipitation after acid precipitation method could significantly increase the content of polysaccharide in extracted crude polysaccharide, polysaccharide content of crude polysaccharide from the original cooking liquor, different temperature concentrated liquid were 82.5±0.3%, 78.8 ±1.5% and 83.3±1.7%, significantly higher than that of direct alcohol precipitation extraction(63.5±2.2%, 68.5±4.6% and 64.7±1.3%) and protein content significantly lower than that of the direct alcohol precipitation extraction method. After treatment of concentrated, acid precipitation, alcohol precipitation after acid: their total recovery rate of polysaccharide was compared to that of the original liquid increased by 12%; the recovery rate of direct alcohol extraction by high temperature concentrated manner was 72.0%, higher than the low concentration(65.1%).4. Cooking liquid crude polysaccharides were divided into two components by DEAE-Sepharose Fast Flow anion exchange chromatography(named Peak1, Peak 2). Of these, the peak 2 had a carboxylic group near 1530 cm-1 and 1400 cm-1(C=O asymmetric stretching vibration and O-H angular vibration), and the peak 1 didn’t have, whichshowed that the peak 2 contained D- glucuronic acid.5. The compositions of alcohol precipitation(XC), alcohol precipitation after acid precipitation in the different concentration manner(XS、JS) were measured by high performance liquid chromatography through PMP, the monosaccharide compositions were as follows: Peak 1, mainly glucose(Glc), the contents were 89.72%, 90.24% and 87.36%, respectively; peak 2, mainly glucose(Glc), other monosaccharides included mannose(Man), D- glucuronic acid(Glc UA), D –(+) – galactosamine hydrochloride(Gal N), glucosamine(Glc N), D- galactose(Gal), L- fucose(Fuc), but lack of D –(+) – galacturonic acid(Gal UA). In each peak of the purified polysaccharide, glucose was the most abundant monosaccharide, containing 48.14%, 47.78% and 54.98%, followed by Fuc、Glc N and Glc UA.6. Clam cooking liquid and polysaccharides had some antibacterial properties to all five kinds of experimental strains. The polysaccharides JS and XS showed low scavenging effect of Na NO2, but their NDMA synthesis blocking effect was significant, the highest blocking rate was 40%.