Extraction, Separation, Structure Analysis And Antioxidant Activity Of Buckwheat Bran Polysaccharide

Long history has been taken for the cultivation of buckwheat in China as it has been an important food crop in the west area for its nutrients. At present, the researches of buckwheat are focus on the Tartary buckwheat, while less on buckwheat grains and the use of buckwheat grains are largely confined to the primary processing stage and it is generally accepted by consumers in the form of a variety of raw products, such as soba noodles and buckwheat bread. However the researches of bioactive substances in buckwheat are rare, especially on the properties of polysaccharides in buckwheat.Based on buckwheat bran as main raw materials, buckwheat by-products was extracted by precipitation and then the operations of purification, structure analysis and antioxidant activity were evaluated. The main abstracts are as follows:(1) Polysaccharide of buckwheat bran was extracted by water extract-alcohol precipitation. Using the single-factor and the response surface method to optimize the extraction process and results show that:the best extraction conditions for leaching were temperature at 87?, leaching extracting time at 137 min, ratio of material to liquid at 1:30 (w/v= g/mL). On these conditions, the experiment verification of buckwheat bran polysaccharide has the highest yield, with the actual extraction yield of 4.43%.(2) The polysaccharide was fractionated by (DEAE-52) cellulose column chromatography and purified by Sephadex G-200 gel filtration chromatography. The uniform components of BBP-?, BBP-? and BBP-? were obtained after purity identification.(3) Application of gel filtration method to calculate uniform polysaccharide components of BBP-?, BBP-?, BBP-? molecular weight and the results showed they were 1.56×104 Da,5.85×104 Da and 8.45 x 104 Da. respectively.(4) The analysis by Fourier transform infrared spectroscopy shows that they had typical absorption peak of polysaccharide, proving that three components were indeed polysaccharide substances. BBP-?, BBP-? were ?- pyranose configuration, BBP-? was ?-pyranose configuration.(5) Using environmental scanning electron microscope (SEM) for research of three kind of uniform polysaccharide (x 1000 and x 2500, respectively), BBP-I mainly solid flake and spherical shape. BBP-? mainly flake, BBP-? is given priority to with stick form.(6) The research of antioxidant experiment of BBP in vitro was performed. The results showed that the BBP have certain ability to restore and clearing effect to two kinds of free radical (DPPH·,·OH) in dose-dependent manner. The antioxidant activity was enhanced along with the increase of sample concentration, but was weaken than the Vc.