【作者】 周金湘；

【导师】 陈振华；

【作者基本信息】 湖南大学 ， 材料加工工程， 2010， 硕士

【摘要】 水稻是全世界种植产量最大的农作物,稻壳重量占了稻谷干重的20%。稻壳含有大约36%的纤维素和12%的半纤维素,这些成分都可以通过处理转变为多糖,最终通过发酵转变为乙醇。米糠占稻谷的5%-8%,我国米糠资源总量可达上千万吨,从米糠中提取米糠多糖和米糠蛋白是利用米糠资源非常有效的一条途径。本论文首先研究了稻壳在机械球磨下的水解过程。糖分析结果表明,当采用150粒不锈钢珠子,600r/min的转速,pH4的柠檬酸-柠檬酸钠缓冲液时,稻壳中的纤维素降解率最高,并且降解率随着时间的增加而增加,而使用同样的球磨条件,在水溶液中,稻壳就没有发生水解。对稻壳球磨前后的结构分析,包括XRD,ESEM和FT-IR的分析表明稻壳能在柠檬酸-柠檬酸缓冲液中水解,主要是由于其结晶度和分子结构的改变,而在水溶液中,稻壳只发生了晶体结构的改变,而并没有水解。实验结果表明这种结合机械力与弱酸的处理方式是处理稻壳水解的一种经济有效的方式。本论文还研究了搅拌球磨及超声波处理对米糠多糖和米糠蛋白提取的影响,多糖和蛋白含量分析结果表明,当磨球质量增加为2kg,米糠球磨5min后,多糖与蛋白的提取率达到3.84%和42.8%,但是球磨时间继续增加,提取率没有发生明显变化。另外,加入超声波处理可以使米糠多糖和米糠蛋白的提取率有少量上升,但是这种差异随球磨时间的增加而变得越来越小。米糠蛋白的电泳图表明,超声波对蛋白质分子量分布影响不明显,而球磨时间的增加,使蛋白质降解,分子量变小。同时,本文用机械力化学从球磨机的工作机理,能量转变及能量传递等方面对实验有关现象进行了分析。本论文的研究表明,机械力球磨为稻壳纤维水解和米糠多糖,蛋白提取提供了一种清洁,有效的方式。更多还原

【Abstract】 Rice is the largest food crop world wide. Hull, the outer coat, constitites 20% of dry rice and is comprised of 36% cellulose and 12% hemicellulose. Appropriate saccharification or hydrolysis of this lignocellulosic biomass to sugars that can be used for the production of ethanol. Meanwhile, rice bran constitites 5%-8% of rice, which is more than ten million ton in China, extracting sugar and protein from rice bran is a very effective method for rice bran recycing.Simultaneous wet ball milling and mild acid hydrolysis of rice hull was studied in this work. Ball milling with 150 small stainless steel beads and rotate speed of 600 r/min in citrate solvent of pH 4 was the optimal condition for hydrolysis and the yield of sugar increased with the milling time extended. While rice hull does not hydrolysis in water using the same ball milling condition. Corresponding structure transformations before and after milling analyzed by XRD, SEM and FT-IR clearly indicated that this hydrolysis could attribute to the crystalline and chemical structure changes of cellulose in rice hull during ball milling in mild acid solvent. While, there were only crystalline changes in water. Thus, this economical, combined treatment of ball milling and citrate solvent could be used to hydrolysis of rice hull.Moreover, rice bran was processed by stir milling and ultrasonic treatment to affect bran breakdown and extraction of rice sugar and protein. The sugar and protein analysis results indicated the sugar and protein content of the supernatant fraction increased to 3.84% and 42.8% when using 2kg stainless steel beads, while there was litte further increase with the milling time extend. And ultrasonic treatment had positive effect on extractability, but the effect became less as the milling time increasing. Sodium dodecyl sulfate polyacrylamide gel electrophoresis showed the milling time is a factor of great influence on a molecular weight distribution,even lead to denaturation of the protein,while ultrasonic tratment has litte effct on a molecular weight distribution. Meanwhile, the results were analysed on ball milling working mechanism, energy transformation and transfer using mechanical chemistry.In conclusion, milling is a clean, effective processing way on hydrolysis of rice hull and extractability of rice sugar and protein.更多还原