The Experimental Studies On Quality Of Oil And Cake Based Dry-Extrusion Rapeseed

Extrusion as a new technology was first applied in the oil production industry in the middle of 1960's,now which is the standard equipment in the oil pressing mill.It has advantages in promoting the productivity of extraction equipment,increasing the speed of extraction and decreasing the energy consumption of extraction,compared with the traditional technique.However, the extruders used in rapeseed oil production are wet mode high oil extruding-expansion machines. The processing is prolonged and the energy cost is expensive due to spraying of a lot of vapor.To solve these problems,simplify the processing,and save cost of the processing procedure,dry mode high-oil extruding-expansion machine was designed by professor Shen Dechao.In this thesis,the dry mode high-oil extruding-expansion machine was applied in the extrusion processing of rapeseed.On the basis of the former study,the optimal combination are investigated according to the indicators of extraction oil ratio and residual oil ratio through adjusting the temperature and the length of die diameter.The test scheme of revolving,orthogonal and tropical design of the second power was adopted, and the influence of extrusion parameters,such as the die length,the die diameter,the barral temperature,the rotate speed of screw,the moisture of rapeseed on production capability of extruder,and yield per energy,was studied.The extrusion rapeseed oil and the quality of extracted meal were studied simultaneously.The research detail and results were as followed:â‘ The processing of extrusion-expanding pretreatment of rapeseeds:When the moisture of rapeseed is below 6%,the extruder is blocked to dry-extrusion.The rigidity of the material in the barrel is the same as plastic.The reason is that the hydrophobic groups of protein in the lower moisture material binds and oil molecules are fixed in the network of space at the function of heat and high pressure.Through dry-extrusion on the rapeseeds oil,the residual oil ratio is below 1%.Mathematical model was accepted through respose surface method and evaluating by fuzzy comprehensive evaluation.The evaluation value was forecasted by neural network For ensuring ratio of residual oil lower and higher rate of oil extruded,the maximal comprehensive evaluation value is 1.697 on condition of the die length x₁=50mm,the die diameter x₂=6mm,the barrel temperature x₃=125℃,the rotate speed of screw x₄= 25rpm and the material moisture x₅=6.3%. â‘¡The study on quality of squeezed oil was shown as below:Compared extrusion oil from extruded rapeseeds to pressed oil from traditional process,the peroxid value and acid value of extrusion oil was better than those of oil from tradition process,and the peroxid value was far lower than those of third grade pressed oil national standard;acid value was lower or nearly that of third grade pressed oil national standard;smoke point was higher traditional oil,meanwhile the smoke point was higher than that of second grade pressed oil national standard(205℃,GB1536-2004).The phospholipids content was 0.01%～0.08%,yet that of traditional oil was 0.217%,it was seen that the phospholipids content of extrusion oil was lower than that of traditional oil.The colour and luster of oil through Lovbind tintometer was.that redness was 32～32.2,yellowness 2.9～3.0.The colour and luster was shallower than that of third grade oil was that redness 35,yellowness 4.0,it was said it could save the discoloration cost Compared to traditional oil the extrusion oil was clarity.â‘¢The study on fatty acid total of squeezed oil was shown as below:The function of total fatty acid,unsaturated fatty acid,and polyunsaturated fatty acids are constructed.As to unsaturated fatty acid,the significance of the die length was least and the barrel temperature was the most important,to gross of polyunsaturated fatty acids and linoleic was first, but to linolenin was second.The valve was more than 1.8,moreover the influence of die diameter was changed greatly.To these had 18 carbon atom acid fatty acid,oleic acid,linoleic acid,linolenin, they have different unsaturated double bonds,the changement principle was different,likely because of different chymistry stability.Because the used rapeseeds was low erucic acid species,as to attentioned content of erucic acid, after regression anylsis,it was not found the influence principle,but the content was 0.16%～0.98%.â‘£The results on ntinutritional factors and nitrogen solubility index(NSI) of extract meal was shown as following:Through dry-extrusion on the rapeseeds oil,the extrusion had definite influence on degradation of tannin and phytic acid.and had huge influence on water-soluble protein which value is 33.21%～54.32%.