Thesis (M.Sc.) - Cairo University - Faculty of Agriculture - Department of Agricultural Biochemistry

Crude commercial soybean lecithin was obtained from two different sources (A) and (B), and they were modified physically, chemically and enzymatically in order to improve its emulsification properties and to prepare a nano-liposome from its acetone-insoluble portion (prepared from the physical modification of lecithin). The percentage of acetone-insoluble (A.I.) portion obtained from the physical modification of crude lecithin (B) was higher than that obtained from crude (A) with 67.3% and 60.5%respectively. The chemical modification was done using two methods of hydroxylation (H1) and (H2). H1 gave a higher drop in the iodine value (I.V.) with lecithin (A) with 11.9% drop, while H2 gave a 19.4% drop in I.V. with lecithin (B). The acid value (A.V.) of the enzymatic hydrolyzed lecithin A (ENZ A) was 33.0 mg KOH/g and 32.5 mg KOH/g for (ENZ B).All the modified lecithins (except the ethanol-insoluble lecithin) were used in the preparation of oil-in-water (O/W) emulsions. Enzymatic hydroxylated lecithin (H2 A and H2 B) showed the most stable zeta-potential, followed by the hydrolyzed lecithin (ENZ A and ENZ B). Acetone-insoluble lecithin Emulsions showed the best results in terms of particle size, poly-dispersity index (PDI), zeta-potential values and physical stability during three months of storage. The chemically modified lecithin by hydroxylation showed the highest zeta-potential values for H2A and H2B samples (-55.3 mV and -50.8 mV), respectively. It also showed a relatively low particle size (284.0 nm and 268.4 nm) and a multiple dispersion index (PDI). It is (0.378) for sample H2A and (0.391) for sample H2B. Whereas, the emulsions stabilized by enzymatically modified lecithins (using PLA2 enzyme) possessed the lowest particle size with a zeta-potential values indicating moderate emulsion stability (-34.8mV) and (-32.2mV) for H2A and H2B respectively

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