Saturated bicyclic fatty acids formed in heated sunflower oils

On the basis of the mass spectra of the dimethyloxazoline (DMOX) derivatives and picolinyl esters, several C-18 bicyclic fatty acids, belonging to four basic structural types, have been characterized from heated sunflower oil. There were fatty acids with six-membered rings either from C-10 to C-15 or from C-7 to C-12 of the parent C-18 fatty acid, and acids with five-membered rings either from C-10 to C-14 or from C-8 to C-12. Ln every case, a bond across the ring gave the bicyclic structure but the position of the bond could not be determined. It is likely that the bicyclic acids are derived from linoleic acid by free radical mechanisms via cyclohexenyl and cyclopentenyl intermediates. (C) 1997 Elsevier Science Ireland Ltd.