The Phospholipids of Oilseeds With Special Reference to Groundnut

A method has been devised for the isolation of free and combined sterols from crude phospholipids, and has been applied to lipid fractions from groundnut, rapeseed and linseed. Sterol glycosides were found to comprise 2 - 3% of the crude phospholipids from each of the three sources, which also contain significant quantities of free and esterified sterols. Fractionation of the glycoside and non-glycoside sterols fom groundnut phospholipids showed that the sterols from either source consist primarily of β-sitosterol with considerably smaller quantities of stigmasterol and β-sitostanol. None of the procedures generally employed in the purification of crude phospholipids are effective in removing sterol glycosides, but free sterols and their esters can be removed with comparative ease by several methods.
Small amounts of free sucrose, stachyose and raffinose have been found in crude groundnut phospholipids, which also contain coublcee glucose and galactose, in addition to arabinose and galactose which have been isolated by other workers from similar materials. Mannose could not be detected in any groundnut phospholipid fraction. The long-chain amines present in groundnut phospholipids comprise a mixture of phytosphingosine and an unsaturated analogue. The other amines present, which were detected on paper chromatograms with ninhydrin, can in the main be accounted for by serine, ethanolamine, glucosamine and their hydrolysis products, although the crude phospholipid yielded a small proportion of material rich in nitrogen and which contained several unidentified amines.