Effect Of Dynamic High Pressure Microfluidization On Properties And Structures Of Hemicellulose

The dynamic high pressure microfluidization (HPM is a new way of physical modification. The results have shown that the property of dietary fiber has improved greatly after HPM treatment, and the content of soluble dietary fibre increased probably because of the hemicellulose in insoluble dietary fibre being modified;At the same time, hemicellulose has special physiological functions,and it can be used as the new-type material of Industrial polymer,but the complexity of their structures limited the exertion of its various property. Hemicellulose A and hemicellulose B were separated from dietary fibre by alkali extraction and acid precipitation in the paper. The effect of HPM on its property and structure were stuided by dealing it with HPM,and the modified mechanism of hemicellulose was discussed, providing the thought for the reason of the modification of HPM on dietary fiber and providing theoretical basis for physical modification of hemicellulose.The results of the paper were as following:(1) Caustic extraction-ethanol precipitation method was combined with orthogonal regression rotation design,and the optimal separation process of hemicellulose was optimized: liquid-solid ratio was 21:1, extraction temperature 35.5℃, extraction time 5.3h, on this condition, the extraction rate of hemicellulose was 30.15% and the purity was 92.34%;DEAE-Sepharose Fast Flow ion-exchange column chromatography was used to separate two components( HCLB-Ⅰand HCLB-Ⅱ); the optimal separation process of cellulose was obtained by combining the acidic sodium chlorite with orthogonal design:pH was 3.5,temperature 90℃,time 150min,liquid-solid ratio 35:1, on this condition,the extraction rate of cellulose was 37.05%.(2) After being dealed with HPM,the expansibility,binding force of water and solubility of HCLA improved in different degree. When the liquid-solid ratio of HCLA was 35, the solubility of HCLA was 12.4 times of the material after being treated with high pressure of 180MPa ;the increase of liquid-solid ratio would make the solubity and retention ability increase;HCLA solution showed the character of pseudoplastic fluid,and its apparent viscosity was improved by HPM The apparent viscosity after being treated under 180MPa increased to 703.1 mPas from 158.7 mPas of common homogenization,but the non-newtonian fluid property didn't change; the higher of the feed concentration was, the bigger of the apparent viscosity was. The fluidity of the binding force of water of HCLB after being treated with HPM reduced, the fluidity of free water reduced first ,then increased; High-concentration HCLB was pseudoplastic fluid, after being treated with HPM, its apparent viscosity reduced; low-concentration HCLB had the charcter of the newtonian fluid, the effect of HPM on its apparent viscosity reduced.(3)After being treated by HPM, the tighten and compact grain structure of HCLA became the loose slices on the surface having hollow pore;the average reduced first,then increased; it reduced to the minimum 465.3nm from 1999nm of the material under 100MPa; The specific surface area increased at first, then reduced. It increasedto 1.99 m~2/g from 0.42 m~2/g of the material under 100MPa; FT-IR spectra has shown that the mixture of cellulose-hemicellulose disappered. After being treated by HPM , the particle size of HCLB reduced at first,then increased; the specific surface area changed litter; the morphology of grain and the x-ray diffraction didn't change.(4) After being dealed with HPM, the molecular weight of HCLA reduced. Some HCLA of big molecular weight were broken to small molecule substance; the contents of Xylose reduced ,the contents of arabinose and glucose increased;The content of galactose and mannose have not changed; the characteristic absorption peak at 894.9cm-1;the other characteristic absorption peak showed blue shift or red shift in different degree, the peak intensities had some changes .The molecular weight and monosaccharide composition of HCLB didn't change; characteristic absorption peak showed litter blue shift or red shift after being treated by dynamic high pressure micro-fluidization technology.