The Studies On Preparation Of Rapeseed Protein Concentrate By Cold-presing

Rapeseed is a kind of important plant oil resources, but it contained glucosinolate and otheranti-nutrients in rapeseed meals, to the application in the aquaculture industry is limited,can not be used as a food protein resources either. In this study, it is based on peelingrapeseed which is under cold-pressing process as raw material, and then use alcoholextracting the cake, to obtain the rapeseed protein concentrate with high protein contained,low residual and anti-nutrients, and modified the production. This study is in order to applyfor high-level feed consumption even the protein concentrate as food to theoretical andtechnical supports.To peeling and hydraulic cold-pressing rapeseed cake (about17%residual rate) as rawmaterials, through the single factor experiments and orthogonal test, under the optimumextraction conditions of extraction temperature45℃, solvent ratio (ethanol: hexane)7:3, theratio of1:10,85%ethanol concentration, extraction time of50min/times,5times, areobteined rapeseed protein concentrate as follows: protein content (dry basis)70.45%, residualoil0.95%, phytic acid1.21%, tannin1.35%, glucosinolates were not detected.It has studied on the spiral low temperature pressing technology of rapeseed and took thecold-pressed cake (about10%residual oil) as materials, by single factor experiments andorthogonal experiment to determine the optimum conditions of prepare the proteinconcentrate by ethanol washing. In the pressing process: first pressing, pressing chambertemperature of40℃, pressing screw speed of35rpm, virgin mouth diameter of12cm;secondary pressing, pressing chamber temperature of40℃, pressing screw speed of35rpm,virgin mouth diameter of8cm; third pressing, pressing chamber temperature50℃, pressingscrew speed30rpm, virgin hole diameter6cm; forth pressing, pressing chamber temperatureof30℃, pressing screw speed of30rpm, virgin mouth diameter of6cm; protein optimumpreparation: extraction temperature45℃, extraction duration of55min per times, mixedsolvent ratio of7.5:2.5, extraction series4times, the solid-liquid ratio of1:7.5,75%ethanol,under these conditions it’s got the protein products with65.04%protein content, residual oilrate of0.81%, phytic acid1.35%, tannin1.64%, glucosinolate not detected. To recovery thesolution and oil from the alcohol washing processes productions, it studied on the recoveryprocesses. Extracted solution has been standing at room temperature, stratification, rotatingevaporation respectively after separation, get hexane phase containing7.34%oil, ethanolphase containing oil, residual2.26%oil. It can be effective to recovery the oil, so use ofmixed solvent product the alcohol washing rapeseed protein concentrate is feasible. To study on the feasibility of rapeseed protein concentrate for food proteins with itsfunctional properties, this paper explored the water bath heating method to improve theprotein functional properties. By single factor and orthogonal test,and took the NSI and theemulsification as the goal, it optimized the best modification conditions were pH value of9.0,the heating temperature of80℃, heating time of6min, solid-liquid ratio of1:8. Under theseconditions it could get the products which water soluble, emulsification and gelation hadgreatly improved.Compared the differences of structure before and after modification rapeseed protein.Electron microscopy showed that the modified rapeseed protein had larger porosity; thestructure becomes more loose uniform. Polyacrylamide gel electrophoresis showed themodified rapeseed protein dissociated more smaller protein molecule. The curve fittinganalysis of infrared spectra said that the secondary structure of proteins after the modificationof the free coil structure, β-angle ratio decreased. These structural changes to improve itsfunctionality are consistent.