Lipid and Triacylglycerol Compositions of Total Lipids in Pumpkin Seeds

Abstract

Lipid and triacylglycerol compositions of total lipids in seeds of five cultivars of pumpkin ('Shintosa', 'Kinuta', 'Tokyo', 'Chikanarihoko' and 'Shirokikuza') were determined by combination of techniques of selective hydrolysis with pancreatic lipase, thin-layer chromatography and gas-liquid chromatography. Total lipid content of the pumpkin seeds ranged from 29.1% for 'Shirokikuza' to 37.4% for 'Shintosa'. Total lipids consisted of triacylglycerols (68.3-82.3%), diacylglycerols (2.5-8.7%), monoacylglycerols (1.0-2.9%), free fatty acids (6.2-10.3%), sterols (1.0-1.3%), sterol esters (0.6-1.0%) and compound lipids (4.0-7.3%). Total compound lipids had five fractions as follows: phosphatidylcholine (21.6-25.4%), monogalactosyldiacylglycerols and phosphatidylethanolamine (15.4-25.9%), phosphatidylinositol (16.0-23.2%), acylsterylglucoside, cerebroside and unknown material (11.5-24.0%)and phosphatidylserin and unknown material (16.4-18.9%). The major fatty acids in each lipid fraction were oleic (18.1-52.0%), linolic (22.6-49.6%), palmitic (8.7-36.2%) and stearic acids (3.8-10.5%). Triacylglycerol composition was calculated from the fatty acid compositions in the triacylglycerol fraction by selective hydrolysis with pancreatic lipase. Main triacylglycerols of pumpkin seed consisted of POO, OLP, OOO, OOL, OLO, LLP, LLL, LLPP, LOL and PLP (P: palmitic, O: oleic and L: linolic acid).