Production and quality improvement of soybean lecithins from crude soybean oil

Abstract

Soybean lecithins from soybean oil have been prepared on laboratory scale, in order to find the optimal amount of water for hydration and optimal degumming temperature for the production of soybean lecithins. The methods were degumming of raw oils with water, separation of gums from oil-water mixture by centrifugation and vacuum-drying of the separated gums. Soybean oil contained 2.5\% phosphatides of which 78\% could be recovered by degumming at 75$^\circ$C with 5\% water. In the production of soybean lecithin, amount of water for hydration was more important factor than degumming temperature. Purified soybean lecithins from crude soybean lecithins were obtained by solvent treatment, and phosphatidyl coline content in the lecithins were analyzed by TLC and HPLC. Fractionation with acetone increased the phosphatidylcholine concentration from 19.7\% to 28.3\%.Further, fractionation with acetone followed by 2-propanol increased the content to 58.0\%. The 3-fold increase of phosphatidyl choline concentration could improve emulsifying property of the soybean lecithins. To remove the color of soybean lecithin, the bleaching experiments had been studied. Use of hydrogen peroxide concurrently with benzoyl peroxide was proved to be more effective. To identify the change to sources of color in bleached-soybean lecithins, scanning methods were carried out. In order to obtain the light colored lecithin for the processing soybean lecithins, temperature of degumming and vacuum drying should be below 75$^\circ$C, and short time of vacuum drying was more effective.