Research On Techniques Of Enzyme Deactivation And Extruded Expansion For Rice Bran And Expander

Rice bran is a by-product which is produced in the process of the rice.It is nutritive and plays the main role in producing the rice bran oil.Due to the severe oil self-production situation in the mainland of China,the enhancement of productivity of rice bran oil has been drawn attention in recent years and it will take an effective measure in the improvement of the reality.One of the main problems in the rice bran oil industry is the rancidity of the fresh rice bran.Although the rice bran contains a high amount of oil,the rancidity nowadays is still the main challenge which the relevant workers should face.Therefore,how to lower and restrain the rancidity rate is an important part of the job for workers in rice bran oil industry,for it seems so much important.In the thesis the researcher developed a vessel machine called Rice Bran Enzyme Deactivator and measured the acid value and moisture content of the rice bran processed.The research content could be summarized into several items in the following list:(1)The research in the thesis is based on the investigation in real factory for the stabilization of rice bran.Researcher has measured some physical properties of rice bran.The Rice Bran Enzyme Deactivator is designed and manufactured in the premise of the existing extrusion process route.Auto CAD is applied for the drawings before the manufacture and assembly of the Deactivator.In the meanwhile,some tasks such as the design and check for the parameters as well as 3D modelling of key components are also carried out.(2)The fluid-mechanical analysis of the rice bran flow in the last vessel on the extruder is also executed by the means of the software called Ansys.One of a simulation unit called Fluent is applied in terms of simulation of volume fraction and temperature,while the moisture content is hard to be simulated by it.The curve that volume fraction versus moisture content is drawn by Matlab.After the simulation on Ansys Workbench,there is a conclusion that the simulated moisture content of rice bran after being extruded is 18.15% when the rice bran of moisture content 16.7% is put into the last vessel for stabilization.The output temperature of rice bran being extrude is estimated at 105.2.Moreover,setting different moisture content of the rice bran fluid at the entrance of the last vessel on extruder during the simulation process for extrusion has contributed to various simulated moisture contents when it comes to the extruded rice bran.Simulated results in terms of moisture content and temperature are much closed to the real values of these variables.It means that multi-phases flow simulation process illustrated in the thesis can be referred to predict the parameters of process route.(3)When the Rice Bran Enzyme Deactivator has been assembled,the single factor tests are applied.The highlights of these tests are put on the change of acid values and lipase activities before the best deactivation parameters,which are 100 /35 min,are concluded.Under such best circumstance,the rice bran sample for further extrusion has been produced,then it is processed in the Mini Rice Bran Extruder.Various parameters,including diameter expansion rate,volume density,moisture content,acid value as well as temperature of rice bran at the output of the extruder,are measured.When comparing the result of the experimental group and control group,differences between these results are clear and the performance of the experimental group is better.The increase of acid value of extruded rice bran after being processed by the best deactivation parameters is only 0.72 mg/g,which is measured after being stored in the following simulated storage experiment in which processed rice bran has been stored in the temperature of 40 for 3 days.By comparison with the control group,the conclusion is that such best enzyme deactivation parameters works when it comes to the storage for rice bran in summer.