The Enzymatic Modification Of Soybean Lecithin

Soybean phospholipid(SBPL, also called soybean gum) is a by-product of the soybean oil production. Following hydration and purification, SBPL is further processed into the marketable product soy lecithin. The purpose of this study is to make high quality lecithin by enzymatic modification with phospholipase A₁.The hydrated soybean oil gum and the concentrated SBPL were treated with phospholipase A₁ by factors×levels orthogonal test with 3×3 and 4×3 respectively. Acid value was measured as the index to monitor the optimum conditions for the enzymatic modification. The optimum parameters for the modification of the hydrated soybean oil gum are 0.4μl/g of phospholipase A₁ with the rotation of 300 rpm, temperature of 60℃and the reaction time of 5h, leading to the increase of acid value from 20.3 to 60.65 mgKOH/g lipid. Regarding the concentrated SBPL 1.4μl/g, 300 rpm, 30%, 50℃and 5 h respectively were obtained for the yield of acid value from 44.38 to 68.28 mgKOH/g lipid.The component's change of concentrated SBPL was analyzed by high-performance liquid chromatography(HPLC), with column micro packs 1-5(30 cm×4.6 mm), flow rate 0.5 ml/min, temperature 30℃, detector wavelength 205 nm and the mobile phase of 39:53:8(v/v/v) of hexane: isopropanol: 1.8% glacial acetic acid. The hydrolyzed rate of 90.2% was yielded by peak area calculation.The hydrophile-lipophile balance value(HLB) was also assayed. HLB was increased from 5 to 14 after hydration. The optimum emulsification conditions were pH 5 and liquor's concentration range 0.5-10%.The best conditions to obtain the acid value of 94.10 mgKOH/g lipid and the yield of 37.6% were five times ethanol, rotation speed of 300 rpm and 1 h under 30℃.Compared with other methods, the current one shows easy control reaction conditions, high percent conversion, low cost and high safety.