Research Of Enzymatic And Ionic Liquid Aqueous Two-phase Extracting And Separating Rapeseed Protein

In our country, protein resource is rather limited, so it will be an important socialand economic significance if we can transform a large amount of cheap rapeseedprotein that as a complete and high quality vegetable protein into high quality foodprotein source. Based on the traditional method of water phase, enzymatic hydrolysisincreases the process enzyme hydrolysis which can effectively improve the extractionefficiency of rapeseed protein. Ionic liquid double water phase is a new efficient andgreen separation system, comparied with the traditional organic solvent extractionmethod, it is non-toxic, safe, fast and simple, so it takes the attention of academia andindustry. In this paper, we used the high-temperature pressed rapeseed as raw materialand applied the technology which combines multi-enzyme with alkaline extraction andacid precipitation to extract crude protein. Meanwhile, we studied the phase behavior ofionic liquid/salt aqueous two-phase system and used [Bmim]Cl/K2HPO4system for thepurification of rapeseed protein. The concrete research content is as follows:(1) Applied the new technology which combines multi-enzyme with alkalineextraction and acid precipitation to extract rapeseed meal protein. And exploringdifferent enzymes and their content on the influences of rapeseed protein extractionefficiency, utilized L9(34) orthogonal optimization experiment to get the optimumconditions of multi-enzyme digestion: A multi-enzyme with α-amylase+cellulase wasappropriate, which the added amount was cellulase45U/g, α-amylase90U/g,temperature50℃, pH9.0, solid-liquid ratio of1∶10. Under the optimal conditions,the protein extract derived from verification experiment was98.96%, the protein yieldwas25.37%and the protein content of rapeseed protein products was76.50%. Theproducts were fine grain and light yellow powder solid with no special odor，At thesame time we,also examined the methoud of the ultrasonic assisted enzymaticextraction of rapeseed protein, and gained the process optimal conditions: ultrasonictemperature50℃, ultrasonic time2h, ultrasonic frequency for100HZ, ultrasonic wayfor all clearance mode of operation, and protein yield was28.56%, the product proteincontent was82.22%. It showed that the ultrasonic assisted enzymatic hydrolysis isbeneficial to the improvement of protein extraction efficiency;(2) Measuring the solubility curves of t hydrophilic ionic liquid [Bmim]Cl（1-ethyl-3-methylimidazolium chloride）/K2HPO4systems by turbidimetric method at 30℃, and Using regression method got the solubility curve empirical equation andcorrelation that is high to0.99. Then, we drew [Bmim]Cl/K2HPO4ternary system phasediagram and set up a method to measure the liquid-liquid equilibrium data of thesystems. Finally, we also studied the temperature on the influence of the system phasediagram;(3) Set up A new method to extract rapeseed protein in [Bmim]Cl/K2HPO4aqueous two-phase system; The effects of concentration of ionic liquid, salt andrapeseed protein and solution pH value on the extraction efficiency were investigated inthe ionic liquid aqueous two-phase system; And made L16(45) orthogonal experiment toget the optimum conditions of extraction of rapeseed protein in ionic liquid aqueoustwo-phase system: the addition of [Bmim]Cl350mg/mL, K2HPO4150mg/mL andrapeseed protein70.0mg/L, pH6.8. The verification experiment results showed thatunder optimum conditions rapeseed protein extraction rate reached99.1%;(4) Determined the solubility of the product, oil absorbency, water bindingcapacity emulsification and emulsion stability, foaming ability and foam stability, andthe amino acid composition. The results showed that in the deviation isoelectric pointarea rapeseed protein has good function and the characteristics of the amino acidspecies is well-found, the proportion of equilibrium, of which the essential amino acidcontent is44.52%of the total content.