Physicochemical Properties Of Oat Polysaccharide And Effect On Growth Of Mice

Oat polysaccharide is a kind of non-starch and water-soluble dietary fiber in oat bran. Oat polysaccharide has many bioactivities, such as blood sugar lowering, lipid-lowering and so on, and the role of its medical value and health improving functions have been recognized by Chinese and foreign medical profession. In this paper, the extraction method, structure, physicochemical properties and effects on mice’s growth of oat polysaccharide from naked oat bran were studied.The optimal extraction parameters of oat polysaccharide, which were60℃, solid/liquid ratio:1:10, extracting3times, and1.5h per times, were gained by orthogonal experiments. With this extracting method, the yield of oat polysaccharide was10.92±0.03g/100g.The effects of pretreatments, including steaming, extrusion and superfine grinding, on extraction of oat polysaccharide were explored. The results showed that the best parameters of steaming, extrusion and superfine grinding were60%of moisture content, pH7.0;10%of moisture content,140℃; and one times, respectively.The effects of sucrose and salt on the viscosity, foaming and water binding capacity of various oat polysaccharide samples were determined. According to the results,1%of sucrose could enhance the viscosity of oat polysaccharide solution, especially the sample from steaming treated oat bran, while foaming ability, foam stability and water binding capacity were reduced. In1%of NaCl solution, sample from steaming treated oat barn had the maximum viscosity and foaming ability whereas sample from extrusion treated oat bran had the minimum viscosity, best foam stability and water-binding capacity.The structure and conformation of oat polysaccharide were studied by scanning electron microscopy (SEM), laser particle size analyzer, scanning circular dichroism (CD), differential scanning calorimetry (DSC), X-ray diffraction. The results of SEM and laser particle sized analyzer observation showed that extrusion and steaming pretreatments could enhance the average granules sizes of oat polysaccharide while superfine grinding pretreatment could reduce it. Alls these three kinds of pretreatments could extend the range of granules size of oat polysaccharide. CD determination suggested that the conformation of oat polysaccharide had good stability in alkaline solution, but poor stability in acidic solution. High temperature (100℃) could change the conformation of oat polysaccharide in distilled water. The Tm of sample from untreated, superfine ground, extruded and steaming treated oat bran were304.94℃,297.12℃,310.27℃and296.04℃, respectively. And their chemical bonds were broken at405.83℃,433.07℃,412.97℃and382.58℃, respectively. X-ray diffraction observation showed that polysaccharide from untreated and superfine ground oat bran had higher crystal ratio than that of polysaccharide from extruded and steaming treated oat bran.The results of growth improving experiment showed that oat polysaccharide form untreated or treated oat bran had no bad effects on growth of mice.