Preparation Of High Quality Lecithins By Inorganic Membrane Separation And Its Industrial Production

For domestic technical difficulties in high quality lecithin products development and industrialproduction in taking off impurities, decoloring, desolvating and taking off the oil aspects, thefeed-grade lecithin was used as raw material in this research, solving these difficulties using thenew and high efficient inorganic membrane separation technology through deeply systematicresearch, establishing the production technology of high quality food-grade lecithin and powderlecithin, and conducting industrial production practice.Firstly, the feed-grade lecithin was used as raw material, lecithin concentrate contained lowcontent of impurities was prepared using inorganic ceramic microfiltration membrane. Under thecondition of moisture content0.1%, membrane aperture0.20μm, solvent/material6:1, filtrationtemperature50°C, and the material flow3m/s, acetone insoluble content of products more than60%and ethyl ether insoluble content could be steadily controlled under0.05%. In examining therelationship between process parameters, such as film pipe diameter, pressure, solvent ratio,temperature, membrane flux and the product index, the clean method of membrane pollution andcomposition film microfilter intercept content were studied. After filter6h, the film must becleaned, and the cleaning effect was the best using2g/dL NaOH solution in80°C washed thefilm2h. The composition of intercept mainly include45.64%protein,33.22%carbohydrate(including15.86%water-soluble polysaccharide) and ash. Its component closed to soybean meal,and had good thermal stability, which was rich in inorganic mineral elements. The results showthat the above material is the main factors which affect impurity and transparency of domesticlecithin concentrate.Secondly, membrane microfilter lecithin concentrate was chemical decolored using the foodgrade hydrogen peroxide. The results of these study show that temperature, time and amount ofdecoloring agents adding are the important conditions influence bleaching. Under the condition of40°C,60min decoloring time,2.5%decoloring agents addition, Gardner colour, acid value andperoxide value of decoloring lecithin was9.6,34.5mgKOH/g oil,16.15mmol/kg, respectively.After prior solvent evaporation, acetone insoluble of product was greater than61%under50°C,0.18kPa pressure using the film evaporation. And after further short-range distillation under thecondition of scraper speed100r/min, feeding rate7L/h, preheat temperature90°C, thecondensed water temperature25°C, temperature100°C, in addition to acetone insoluble morethan62%, other parameters, such as ethyl ether insoluble, peroxide value, Gardner colour, volatilematter were less than0.05%,3.5mmol/kg,9+,50mg/kg, respectively, transparency of productwas good, satisfying the first level standards of lecithin concentrate and ADM food-grade lecithin. Based on the principle of the lecithins form big size reverse micelle in nonpolar solvent, asystematic study on the factors effect lecithin reverse micelle size in hexane-water system usingdynamic light scattering was conducted. Research showed that, the solvent ratio, water additionand temperature had significant effects on the size of reverse micelle, reverse micelle size firstincreased with water added, then decreased, increased with the decrease of the solvent ratio andtemperature. The experiment indicated that average particle size of lecithin reverse micelle was9.8nm, more than98%of the particle size was greater than5nm. So choosing5nm inorganicceramic membrane intercepted lecithin reverse micelle through the ultrafiltration, removingtriglycerides from the food-grade lecithin. The components of food-grade lecithin solution werevery complex. It could forecast the chang rule of fouling heat resistance and flux of ultrafiltrationmembrane with the ultrafiltration time throughing the growth curve model, which could providethe theoretical guidance in improving the membrane separation efficiency for the industrialproduction controlling film filtration process.Based on the above laboratory test, food-grade and powder lecithin were produced underindustrialization amplifier, throughing the test and production debugging work, established thetechnology of high efficient membrane production of high quality food-grade and powder lecithin,and the indexes of corresponding products achieved and even exceed corresponding foreignproduct standards. Throughing the project practice of industrialization, reversed the situation ofsuch products of our country completely dependent on imported, realized the high quality lecithinproduct localization, breaked long-term technical monopoly of abroad, and enhanced lecithinprocessing enterprise’s core competitiveness of our country. As the main contents of "soybeanlecithin production key technology and industrialization development" project, it was awardedsecond prize in2010National Science and Technology Awards.