MODIFICATION OF SOME LECITHINS WITH A PRELIMINARY APPROACH TO NANO-LIPOSOME FORMATION

Abstract

The present study was carried out in order to prepare different lecithin fractions obtained by modification of crude commercial soybean lecithin to be used in the preparation of nano-liposomes, and as emulsifiers. The obtained results can be summarized as follow: 1. Crude lecithins were semi-liquid at room temperature, and their physical and chemical parameters were in accordance with what was found in the literature. 2. The percentage of the prepared acetone-insoluble lecithin ranged from 60.5% to 67.3% for lecithin (A) and (B) respectively. 3. Absolute ethanol gave higher yield of ethanol-insoluble lecithin fraction that ranged from 25% to 30% for lecithin (B) and (A) respectively. 4. The highest drop in iodine value (after hydroxylation of crude lecithin) was achieved by H2B with 19.4%, while the lowest percentage was achieved by H2A with 6.8%. 5. The detected hydroxy-fatty acids by GC-MS were derived from linoleic acid and linolenic acid. 6. Moderate hydrolysis was done for crude lecithins by the use of phospholipase A2 enzyme, and the increase in acid value after hydrolysis ranged between 5.2% to 24.3 for lecithin (B) and (A) respectively. 7. The major fatty acid of crude soybean lecithin was linoleic acid, and it was noticed that the modification (in particular the hydroxylation and hydrolysis) has influenced the fatty acid composition of the prepared fractions. 8. The phospholipid composition of all lecithins was determined by HPLC, and an unusual PC:PE ratio was observed in crude lecithins. 9. Hydrolyzed lecithin-based emulsions possessed the lowest particle sizes along with an intermediary PDI values and a zeta potential that could be linked to a moderate emulsion stability, while the highest zeta potential values were achieved in the hydroxylated lecithin emulsions, with a relatively low particle sizes of 284.0 and 268.0 nm respectively and low PDI values of 0.378 for H2(A) and 0.391 for H2(B). Whereas, the lowest PDI value was achieved by the emulsion stabilized by H1 (B). 10. The emulsion of acetone-insoluble lecithin AI (B) had a relatively low particle size of 255.0 nm and a high zeta-potential value of -48.6 mV which is a value that could be linked with a good emulsion stability as mentioned before. It is worthy to mention that this sample (AI B) had a pH of 6.72. 11. Concerning the physical stability of the prepared emulsions, the results revealed that AI (B) had a physical stability of 92% during the first week of storage and a value of 89% after 3 months of storage. Although the emulsions stabilized by crude lecithins possessed the highest physical stability in the first week, their physical stability has dropped to 85% by the end of the storage period. It is worthy to mention also that regarding the physical stability, AI(A) and the standard AI were having the same physical stability of 92% as AI (B) during the first week but during the twelfth week of storage their physical stability was slightly lower than that of AI (B) with a percentage of 88%.