Antioxidant activity of modified sunflower lecithins

D. M. CABEZAS; M.C. TOMÁS

Québec City, Canadá

Congreso; 98th AOCS Annual Meeting & Expo; 2007

AOCS

Lecithin is used as emulsifier,dispersing and antioxidants agents in the food industry. Lipid oxidation is an important deteriorative process of nutritional, organoleptic and functional characteristics in edible oils. Phospholipids are metal chelators and have catalytic effect on the decomposition of hydroperoxides and tocopherols.The aim of this work was to study the effect of different modified sunflower lecithins on the oxidative stability of refined sunflower oil. Sunflower lecithin was treated with absolute ethanol and acetone obtaining the enriched PC and PI fractions and deoiled lecithin (DL). Phospholipid composition and tocopherols were determined. Antioxidant activity of modified lecithins (250-2000ppm) was estimated by induction time (ti) (Rancimat 98ºC,air flow 20Lh-1). Enriched PC fraction recorded a strong increase of ti, at 1000 and 2000 ppm (100-150%). For PI fraction, a significant increment of ti, (35%) with 500 ppm was observed remaining constant until the upper limit of the range. DL presented an improve in oxidative stability of oil as a function of increasing concentration (ex. 50% at 2000ppm). These results could be attributed to the different phospholipid composition of PC fraction (76%PC,4%PI,9%PE), PI fraction (25%PC,46%PI,9%PE) and DL (38%PC,36%PI,13%PE). PC fraction exhibited the best antioxidant activity due to the more contribution of PC and a synergistic effect with tocopherols (674ppm)