Abstract

The pulp of the African pear (D.edulis) fruits were investigated for its oil compositions, major lipid classes and constituents fatty acids from 4 weeks after anthesis (WAA) to fruit maturation.  The oil was extracted with n-hexane using soxhlet extractor and characterised by gas chromatography. Fatty acid profile showed a saturated acid content of between 19.5 and 36.5% and unsaturated fatty acid content of 63.5 to 80.5%. Fractions of different fatty acids were synthesised at different stages of fruit development and the predominant fatty acids were palmitic acid (31.0%), stearic isomer (20.9%), oleic acid (7.1%) and linoleic acid (43.8%) at matured stage (20 WAA) of fruit development and 10.4, 12.9, 22.7 and 39.8% respectively at the immature stage (4 WAA) of fruit development. Polyunsaturated fatty acids were not detected in the African pear pulp oil throughout maturation. The major phospholipids were phosphatidylcholine (65.2%), phosphatidylinositol (25.8%) and phosphatidylethanolamine (8.9%), while phosphatidylserine (PS) and lysophosphatylcholine (LPC) remains as traces throughout fruits maturation. The pulp major sterol lipids were sitosterol accounting for about 71.3% and campesterol 12.4% of the total sterol lipids. The immature fruit pulp glyceride lipids were diacylglycerides (DAG) and triacylglyceride (TAG) which accounted for 70.2 and 18.6% respectively. In mature fruit pulp, TAG had a dramatic increase to 72.5% while DAG decreased to 22.1%. Major changes occurred in the TAG with fruit maturity with increased in concentration to 72.5% at 20 WAA. Based on these changing patterns of lipid fractions with fruit maturity, possible pathways of TAG synthesis have been proposed. In conclusion, the results at the 18 to 20 WAA showed that high quantities of essential fatty acids are present in the African pear pulp oil at mature stage of the fruits.

Key words: Dacryodes edulis, anthesis, n-hexane, gas chromatography, triacylglyceride.