Study On The Control And Cleaning Technology Of Lecithin Gums In Crude Rapeseed During Storage

In order to avoid a large number of lecithin gums in the crude rapeseed oil to subside on the bottom and wall of the oil tank during storage,nitrogen was used to make the lecithin gums to distribute in the crude rapeseed oil,and the stirring conditions of nitrogen was optimized in this work.The sedimentation regulations of lecithin gums in crude rapeseed oil were investigated in different height of the oil tank.The effects of sedimentation time on lecithin gums in crude rapeseed oil at different temperatures were studied.Acid values and peroxide values were compared in different storage conditions:filling nitrogen every 10 days-storage and standing storage.In the subsequent refining process,degumming is a very important process,the phospholipid in crude rapeseed oil must be removed.Removing Non-hydrated phospholipid is a big challenge.In this study,immobilized enzyme was used to remove non-hydrated phospholipids from crude oil.In this study,the degumming processing and phospholipase Lecitase Ultra immobilization process were improved,the immobilized phospholipase Lecitase Ultra was applied in crude rapeseed oil degumming.(1)Study on the effects of nitrogen-stirring on the lecithin gums of crude rapeseed oil and storage stability of crude oilStorage-temperatures and storage-times significantly affected phospholipid sedimentation rate(P<0.05).After a 10 day-storage at 40?,the lecithin gums subsided at a rapid velocity,the sedimentation of lecithin gums achieved dynamical equilibrium,and the phospholipid content reduced to 1.417 mg/g in crude rapeseed oil.The sedimentation of lecithin gums achieved dynamical equilibrium after a 16 day-storage at 25?,and the phospholipid content reduced to 1.417 mg/g.After a 20 day-storage at 10?,the lecithin gums subsided at a slowly velocity,the sedimentation of lecithin gums achieved dynamical equilibrium,and the phospholipid content reduced to 1.382 mg/g in crude rapeseed oil.The experimental results also showed that the lecithin gums would not subside on bottom and wall of the oil tank filled with nitrogen every 10?20 day under this conditions:nitrogen flow rate of 12 L/min,nitrogen flow time of 21 min in the range of 10?-40?.The oxidation speed of crude rapeseed oil was decreased during the nitrogen agitation storage at the same time.After the nitrogen agitation storage for 180 days,acid value and peroxide value of the crude rapeseed oil were still in the range of acid value and peroxide value provided in the GB 1536-2004 in China.(2)Study on lecitase ultra immobilized by soduim-alginate-chitosan using response surface methodology and its properties of immobilized Lecitase UltraSodium alginate chitosan was used as carrier to immobilize phospholipase Lecitase Ultra.Based on the single-factor test,the immobilizing conditions of Lecitase Ultra by odium alginate chitosan were optimized through Box-Benhnken design and response surface methodology(RSM).The mathematical-regression model was established about the dependent variable(empolying immobilized enzyme recovery rate)and the independent variables(concentration of chitosan(x1),concentration of sodium alginate(x2),concentration of CaCl2(x3),concentration of glutaraldehyde(x4)).The experimental data were processed and the quadratic polynomial mathematical model was gained using the software design expert 6.0 Trial.R = 74.60 + 4.52xi +5.67x2 + 2.17x3 + 2.08x4 + 2.55xix2-0.075xix3 + 0.5x1=4-0.050x2x3 + 2.25 x2x4-0.37x3x4-9.86 x12-19.80x22-5,85x32-4.34x42.According to this model,the optimum immobilzing conditions are determined as the concentration of chitosan of 2.09%,the concentration of sodium alginate of 2.17%,molar the concentration of CaCl2 of 0.28%,the concentration of glutaraldehyde of 0.33%.The predicted value(empolying immobilized enzyme recovery rate)for these optimum values is 76.11%.Under this condition,the test was verified.The results showed that the average recoveries of enzyme activity were 75.57%,and the error value was only 0.54%.At the same time,the enzymatic properties of immobilized Lecitase Ultra were studied.After immobilization,both the pH stability and thermal stability of Lecitase Ultra improved.The optimum reaction temperature of the immobilized Lecitase Ultra was 55?,which was 10? higher than the free enzyme.The optimum pH was 5.0,which was better than the free enzyme.After being used for five times,the enzyme activity was 63.8%of the original,which indicated that the immobilized Lecitase Ultra was very stable.(3)Optimization of degumming process of crude rapeseed oil with immobilized Lecitase Ultra using response surface methodologyThe immobilized Lecitase Ultra was used to degum in crude rapeseed oil.The degumming conditions of Lecitase Ultra by enzyme method were optimized through Box-Benhnken design and response surface methodology(RSM).The mathematical-regression model was established about the dependent variable(phospholipid content of degummed oil)and independent variables(immobilized phospholipase Lecitase Ultra dosage(x1),temperature(x2),pH(x3),time(x4)).The software design expert 6.0 Trial was use to process the experimental data and the quadratic polynomial mathematical model was gained(Y= 5.18-7.54xi-11.91x2 +2.43x3-3.38x4 + 5.15x12 + 26.52x22 + 11.78x32 + 3.03x42-1.25x1x2 + 0.075xix3 +0.5x1x4 + 0.050x2x3 + 2.25x2x4 + 0.37x3x4).According to this model,the optimum degumming conditions are determined as phospholipase Lecitase Ultra dosage of 204.68 mg/kg;reaction temperature of 55.82 ?C;reaction time of 4.58 h;reaction pH of 5.37.The predicted value for these optimum values is 2.96 mg/kg.Under this condition,the test was verified for 10 times.The results showed that the average value was 3.06 mg/kg,and the difference between predictive and experimental value was just only 0.40mg/kg.This model was reliable and effective,and had practical application value.After the degumming process,the residual phospholipid in oil was below 5 ppm,which met the requirements of the dugumming rapeseed oil grade one.