The Investigation Of The Effect Of Ball Milling On Rice Hull Hydrolysis And Extraction Of Rice Sugar And Protein

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.