Study On The Application Of Aqueous Enzymatic Extraction In The Processing Of Rapeseed

Aqueous enzymatic extraction technology of rapeseed oil and rapeseed protein has been reported in many literatures in domestic and foreign countries, however, it can not be applied in industry scale because of its disadvantage such as a large variety of enzymes used, a mass of enzymes added, a long time reaction period and low oil yielding. In the dissertation, the optimum technology and mechanism of aqueous enzymatic extraction of rapeseed oil and rapeseed protein have been studied, in order to extract the rapeseed oil and the rapeseed protein simultaneity. The quality of the rapeseed oil and the rapeseed protein has also been researched, on the base of this, it can do a basic theory of the industry application.This paper studies the process of aqueous enzymatic extraction of rapeseed-oil. The paper includes four parts as follows: the influence of the pretreatment to the aqueous enzymatic extraction of rapeseed-oil,the different methods of enzymolysis and the effect factors, the effect of demulsification to the extraction rate of rapeseed oil,finally we do a research about the effect of enzymolysis to the quality of rapeseed oil anf rapeseed protein.The pretreatment before enzymolysis has a great influence to the extraction rate of rapeseed oil. Adopt The method of combineing dry grinding and wet grinding,first control the rapeseed grain size about 60-80 mesh ,after heat processing then adopt Tissues homogenate machine to homogenate the rapeseed to be the feasible size of enzymatic reaction. The experiment shows that,the highest quantity could be obtained in the condition of the heating time of ol.5h - 2h, the heating temperature of 90°C and the grinding time of 15 minutes.Two enzymolysis methods have been discussed in this research,these are: enzymolysis-extracting; enzymolysis_extracting and re-enzymolysis_re-extracting, at the optimum enzymolysis and extraction conditions ,the extraction rate of rapeseed oil are 86.75%, 90.82% respectively. the extraction rate of rapeseed oil is determined by the following factors: the pH of the system, the solid to liquid ratio, the temperature, the degree of grinding and the dosage of enzyme.In the single factor experiments,the optimum conditions of enzymolysis are: When the enzyme dosage is 2%, pH is 7.0 the treatment time is 4h, the solid to liquid ratio is 1:6,the treatment temperature is 50°C,at this condition the rapeseed oil extracting rate is 86.97%,base on the single factor experiments,we do a orthogonal experiment,then we find that the effect factor primary and secondary list is: the content of enzyme > pH>time> temperature;through optimization the rapeseed oil extraction rate reaches 88.56%.Three demulsification technologies have been researched,those are: the different conditions of centrifugation, Solvents and the combining of centrifugation and Solvents.The results of the experiments showed that: three methods all have a good effect to demulsification, after optimization the extraction ratio are all above 80%, especially the combining of centrifugation and Solvents. The effect is very prominent.The highest extraction rate is96.56%, almost all oil is breakout. Compare three methods, the effect of use single centrifugation or single Solvents is not very ideal,so we should combine them together ,but the technology of the combition may increase cost ,because the large consume of Solvents and need high speed centrifugation machine. we can adopt lower speed centrifugation machine (5000r/min) ,the dosage of Solvents control in 60%,just as the orthogonal experiment 2th the extraction rate of rapeseed oil may reaches 90.18%.The research results of the quality of rapeseed oil and rapeseed protein showes that enzymolysis, may affect the quality of rapeseed oil ,the oil which is made by enzymolysis can achieve the National secondary standard,there are no remarkable change about the relative density,index of refraction between enzymolysis and non- enzymolysis,but the acid value, iodine value,peroxide value is higher than non-enzymolysis,this may has some to do with the heat treatment ,however, the saponification value is lower than non-enzymolysis.In the isoelectric point area of rapeseed, the solubility,moisture retention,foamability, emulsibility are relative lower ,beyond this area ,on the left area of the isoelectric point,the lower of the pH,the higher of the value , on the left area of the isoelectric point area,the higher of the pH,the higher of the value , but foam-stability is opposite, in the isoelectric point area,the foam stability is good. On the processing of aqueous enzymatic extraction,the rapeseed protein hydrolyzed, enzymolysis has some thing to do with the functional characteristic,that is Low-Grade modification,compare to aqueous extraction ,it can improve the solubility,moisture,retention,foamability,emulsibility,oil absorption ability ,but the foam stability and viscosity are lower than traditional extraction ,these changes make them more favorable for food material.