Urea‐based fractionation of seed oil samples containing fatty acids and acylglycerols of polyunsaturated and hydroxy fatty acids

Abstract

The selectivity and efficiency of urea complex (UC) formation-based fractionation of free fatty acids (FFA) were examined. A rapid, simple, and inexpensive procedure recently developed for urea fractionation was applied to lipid mixtures containing various polyunsaturated and hydroxy FFA species. Urea treatment proved useful for isolating polyunsaturated FFA (PUFA) from FFA derived from fish, borage, and linseed oils by removal of saturated and monounsaturated FFA, but was not effective for isolating hydroxy FFA from the FFA derived from castor, Lesquerella, and Dimorphotheca oils. In situations where FFA within the crystalline or UC phase were rich in PUFA, the urea/FFA mole ratio of the UC was relatively higher, with lower recovery of FFA in this phase. The distribution of urea between the crystalline phase and the solvent was not significantly affected by the FFA composition of feed nor the overall ratio of FFA to urea. It was strongly dependent on the overall mass fraction of solvent. Phospholipids and mono-, di-, and triacylglycerols were poor templates for UC formation relative to FFA. Their inclusion in acylglycerol mixtures containing FFA reduced UC formation.

Separation Mechanism of Fatty Acids from Waste Cooking Oil and Its Flotation Performance in Iron Ore Desiliconization

“…MFA could be separated into SFA and UFA with urea inclusion method [26][27][28]. The main process shown in Figure 2.…”

“…When the urea and fatty acids to form a urea inclusion compound, the crystal structure of urea was converted from the tetrahedron into hexahedron with a space group of P6122 [26,28]. Urea molecules were in a spiral way to form the host frame structure.…”

“…While unsaturated fatty acids proved to be an excellent collector suitable for low temperature and as the degree of unsaturation increases, low temperature flotation performance is enhanced [23]. Under certain conditions, urea can form crystalline compounds with linear fatty acids containing 6 more carbon atoms, which can be used to separate SFA and UFA [26][27][28]. With this method, it is possible to separate out the SFA from waste cooking oil to strength its low temperature flotation performance.…”

Methods of concentration and purification of omega-3 fatty acids

“…Urea-based fractionation of fatty acids has been extensively used for enriching omega-3 fatty acids in marine oils (Hayes et al, 2000). Urea adduction of fatty acid ethyl esters of squid (Illex argentinus) visceral oil, using cyclohexane and methanol, can increase the EPA content from 11.8 to 28.2% and DHA content from 14.9 to 35.6% (Hwang and Liang, 2001).…”

Improving the Cold Flow Properties of Biodiesel by Fractionation

“…More recently, urea fractionation was applied in laboratory-and industrial-scale reduction of saturated fatty acid content of low-erucic acid rapeseed oil (Hayes et al, 1998). UIC were employed in fractionation of fatty acid mixtures of marine, borage, canola, linseed, lesquerella, rapeseed and meadowfoam oils (Hayes et al, 2000;Hayes, 2006). This technique was applied in isolation and purification of linoleic acid from sunflowerseed oil (Wu et al, 2008) and oleic and linoleic acids from various vegetable oils (Lee, 2003).…”