Composition of methyl esters from heat‐bodied linseed oils

Abstract

Two heat-bodied linseed oils, with Gardner viscosities of 37 and 55 rain, were saponified, converted to their methyl esters, and separated into 2 fractions with urea and . methanol. Gas-liquid chromatography showed the adduet fraction, which comprised 38-41% of the total methyl esters, to contain: pahnitie, stearic, oleic, "linoleic," and trace amounts of "linolenic" acid. The nonadducting fraction (59-62%) of the total methyl esters was separated by molecular distillation at 140C/7 ~ into a distillate and residue. The distillate amounted to 18-25% of the total methyl esters and had an iodine value ([.V.) of 142-145; its absorption at 232 m~ indicates 2.5-3.0% conjugated diene. Hydrogenation of this distillate gave a liquid product with an iodine number of 4 and a pour point of -50C. Gas chromatograms of the distillate and its hydrogenated derivative indicated at least 5-7 components. Comparison of these peaks with known fatty acid methyl esters indicates that the components of these fractions were either cyclic or branched esters. The nonadducting residue fraction was composed mainly of polymeric acids.

Rapid determination of double bond configuration and position along the hydrocarbon chain in cyclic fatty acid monomers

“…Several decades ago, it was suspected that unsaturated cyclic fatty acid monomers (CFAM) are formed in frying oils. Consequently, several attempts were made to elucidate their structures by various analytical techniques (1)(2)(3)(4)(5)(6)(7)(8)(9)(10). CFAM, which are reported to be potentially toxic (6,(11)(12)(13) and are readily absorbed by the digestive system (14,15), were found at levels up to 0.5% in frying oils collected from restaurants in the United States (16).…”

On the mechanisms of cyclic and bicyclic fatty acid monomer formation in heated edible oils

“…All theses studies, including mechanistic ones, have recently been reviewed [5,15]. Considering the analysis of their possible mode of formation, it was first hypothesized that the pentadienyl system of linoleic acid under-went a thermal rearrangement [16]. In this process, the ring closure between C-9 and C-13 was accompanied by a double bond migration that maintained the methyleneinterrupted moiety ( Fig.…”

Formation of cyclic fatty acids during the frying process

“…The first mechanism to be proposed for the formation of cyclopentenyl fatty acids in heated oils involved an intramolecular rearrangement involving migration of the double bond and abstraction of a hydrogen atom from carbon 11 followed by cyclization [22]. However, the product would be a cyclic monoene with the ring from carbons 9 to 13 of the fatty acid chain, rather than 10 to 14 as was demonstrated in our work, so this proposal is no longer tenable.…”