Studies On Extraction And Antifatigue Of Oyster Glycogen

The purpose of the thesis is to investigate the functional ingredients of oyster and their bioactivities and develop the novel healthy food using these ingredients. After the nutritional components in oyster meat were determined, the research focused on the isolation and purification and fine structure and antifatigue bioactivity of oyster glycogen. Finally, a process to produce glycogen from oyster was optimized. 57.2% of Oyster glycogen was extracted by hot alkaline method, lyophilized to give oyster glycogen as a white powder, contained glycogen 91.10%, protein 2.06%. High performance gel filtration chromatography (HPGFC) showed that the molecular weight of oyster glycogen was about 1.6million in the range of 10⁶¹0⁷(Dalton). The gas chromatography (GC) results showed oyster glycogen was a homogeneous polysaccharide and glucose was its monosaccharide composition.The fine structure of glycogen purified from oyster was investigated by enzymic methods. The results showed that average chain length (CL),interior chain length (ICL) and exterior chain length (ECL) of oyster glycogen were 13, 9and3, respectively. The 3 -amylase limit dextrin of oyster glycogen were completely debranched by joint action of isoamylase and then pullulanse, the ratio of A and B chains in oyster glycogen were 0.88:1.0, and the multiple branching degree was 1.88.The effects of the glycogen extract by five different proteases were compared. The results indicated that the pepsin was the most suitable, the yield is 84.6%. The optimal conditions were: pH4.0, 50℃,4hr and E/S=1600U/gPro. On the optimal conditions, the yield of glycogen reached 91.56%, the DH was 22.26%.The hydrolysate after centrifugation could be separated by ultrafiltration (MWCO10000), then obtaining the solution mainly with glycogen. Glycogen was separated by the ethanol precipitation method, the optimal conditions: precipitated with 3 times volume of 95% ethanol, the yield of glycogen reached 68.8%.The glycogen extract contained glycogen 68.74%, protein 15.89%, fats 8.65%, ash 1.62% and moisture 4.99%. Moreover some minerals and microelements such as Fe, Zn, Mn, Ca were rich in glycogen extract.Oyster glycogen was tested on three different doses(10, 20, 50 mg · kg^-1 · d^-1) in mice. The results showed that oyster glycogen could enhance the storage of muscle and liverglycogen, increase the activity of LDH before and after swimming, decrease the increase of blood urea nitrogen(BUN) after strenuous exercise, and accelerate the clearance of BUN after exercise. Oyster glycogen induced a remarkable adaptability to exercise load. Enhanced resistance and accelerated elimination of fatigue. The dosage of oyster glycogen 20 mg ? kg" 1 ? d"1 was the best amount among the three doses.