Roast Of Oat Grain And Extrusion Of Oat Flour

Oat is a good food material being rich of nutrients and having specific function for human health. Up to now, oat processing in China is mainly focused on manually orperation and low in usage of flour. The thesis identified the critical control point for oat flour processing on the basis of investigation on the current situation, investigated the effect of roasting process on the properties of oat grain and its whole oat flour. Method for evaluating the quality of extruded oat flour products was also studied, as well as the effect of extruding condition on the product quality and the optimization of the extruding parameters. Following is the main results obtained in the study.(1) After investigation and analysis, it was found that the roasting procedure played critical role in the processing of oat flour. It not only affected on the flour properties, but also on the subsequent processing properties of flour. The traditional roasting orperation showed significant effect on the lipid content in oat, but little effect on the crude protein content and crude fiber content. The roasting treatment could cause decrease of gelatinization temperature and increase of hot paste stability and coagulation properties of cool paste.(2)Roasting with infrared radiation and traditional method showed similar effect on the properties of oat grain, which caused decrease of grain test weight but increase of crude protein content. Proper roasting could increase, but less roasting and over roasting decrease the flour extraction rate. The L* value of the roasted grain could be used to evaluate the quality of roasting orperation. Infrared roasting could be a potential method in replacing the traditional method.(3) Among the quality indexes of the extruded oat products, those showing variation more than 5% were a* value, crispness, hardness, water solubility and swelling rate. The indexes having variation rate lower than 5% showed significant correlationship with one or more of those indexes being variation rate higher than 5%. Weights of the indexes for evaluating the quality of extruded products were decided as swelling rate of 21%, a* value of 26%, crispness of 27% and hardness of 26%.(4) Results of the single-factor design and quadratic orthogonal rotation combination design showed the quality of extruded products increased firstly and then decreased with the enhancement of extruding temperature, moisture content in material, feeding speed and screw rotation speed. The processing parameters were optimized as extruding temperature of 161℃, material moisture content of 20%,feeding speed of 43g/min and screw rotation speed of 162r/min。...