Fractionation of Sunflower Lecithin. Characterization and Emulsifying Properties

CABEZAS, D.M.; TOMÁS, M. C.

St. Louis, Missouri (USA)

Congreso; 97th AOCS Annual Meeting & Expo; 2006

American Oil Chemists' Society (AOCS)

Native and modified lecithins are used in a wide range of food applications (emulsifiers, dispersing agents). Phospholipids present interesting surface properties, which enable them to achieve emulsion stability in diverse food products (mayonnaise, salad dressings). The main aim of this work was to study the fractionation process of sunflower lecithin investigating the effect of the emulsifying properties of different fractions on the stability of oil in water (O/W) emulsions. Sunflower lecithin -provided by a local oil industry- was treated with absolute ethanol (ethanol / gum ratio 3:1, 65°C, 1h, moderate agitation) obtaining an enriched PC and PI/PE fractions, respectively. Furthermore, both of them were purified with the addition of acetone to remove the residual oil and dried. Phospholipid composition of different samples were determined by HPLCELSD with a previous purification step by SPE. Oil in water (O/W) (30:70 w/w) emulsions were prepared in an Ultraturrax T25 homogeneizer (10,000 rpm, 1 min) using sunflower oil and different sunflower lecithin fractions (PC, PI/PE and deoiled lecithin) in a range of 0 - 2% respect to water phase. Optical characterization of dispersions was carried out using a vertical scan analyzer (Quick Scan), obtaining the corresponding differential Transmission and Backscattering profiles. The mechanisms of destabilization and the corresponding kinetics involved -in each case- were determined. The results obtained showed that PC enriched fraction contained 85% PC, 10% PE and 5% PI while PI/PE fraction presented 37% PC, 23% PE and 40% PI. All emulsions presented a destabilization process by a creaming process followed by coalescence in some cases. Also, changes in emulsion stability were observed as a function of the type of the emulsifier agent assayed and its concentration. Emulsions with 0.1 to 0.5% PI/PE fraction showed a rapid destabilization process. At higher concentration, it was recorded a higher level of initial backscattering than those corresponding to samples previously mentioned, with a decline of the creaming rate and an increase in emulsion stability. PC enriched fraction exhibited the most efficient role as emulsifier agent in comparison with deoiled sunflower lecithin and PI/PE fraction at all concentrations used, mainly at low concentration levels. These results provide interesting information for further developments in the food industry.