Proximate neutral lipid composition of niger (Guizotia abyssinica) seed
2002
Ramadan, M.F. | Moersel, J.T. (Technical Univ., Berlin (Germany). Inst. of Food Chemistry)
Niger (Guizotia abyssinica) seed was extracted with hexane (H) and chloroform/methanol (CM) (2:1, v/v) to determine the effect of the solvent on the amount and composition of the recovered lipid. The amount of the total lipid (TL) extracted with H was 29.6 % of the seed weight, while that extracted with CM was 49.9 %. Column and thin-layer chromatographic procedures on Silica Gel were performed to fractionate the main neutral lipid (NL) subclasses. Fatty acid composition of the NL subclasses, triacylglycerol (TAG) molecular species, and sterol (ST) concentration were estimated. The NL amount was found to be higher (97 % of TL) in the H extract than in the CM extract (93 % of TL). TAG appeared to be the predominant NL subclass (89.7-91.9 % of total NL). Linoleic (C18:2n-6) and oleic (C18:1n-9) acids were the main unsaturated fatty acids, while palmitic acid (C16:0) was the major saturated fatty acid. TAG molecular species were separated according to their carbon number by high temperature gas-liquid chromatography using a flame ionization detector (HTGLC/FID) and H2 as the carrier gas. TAG of carbon numbers 16 and 18 were contained in six TAG molecular species. The major peaks occurred at C5:6, and C5:3 corresponding to trilinolein and triolein. Furthermore, TAG molecular specie, expected to contain two molecules of linoleic acid (C5:5), was detected in a high level. The major ST found were as follows: beta-sitosterol campesterol stigmasterol D5-avenasterol D7-avenasterol lanosterol.
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