Abstract
Monoepoxy compounds formed after heating methyl oleate and linoleate, triolein and trilinolein at 180°C for 5, 10 and 15 hours, were characterized and quantitated after derivatization to fatty acid methyl esters by using two base-catalyzed procedures. Structures were identified by GC-MS before and after hydrogenation. A complete recovery of the epoxy compounds was obtained by comparing results from methyl oleate and linoleate before and after transesterification, and good repeatability was also attained. Similar amounts of epoxides were found for methyl esters and triglycerides of the same degree of unsaturation, although formation was considerably greater for the less unsaturated substrates, methyl oleate and triolein, possibly due to the absence of remaining double bonds in the molecule which would involve a lower tendency to participate in further reactions. On other hand, independently of the degree of unsaturation of the model systems and of the period of heating, significantly higher amounts of trans isomers were formed. Finally from comparison between the amounts of epoxides and the level of polar fatty acids in samples, it was deduced that monoepoxy compounds were one of the major groups formed under the conditions used.
Highlights
Degradation compounds formed at the high temperature of processes like frying have been extensively studied (Nawar, 1985; Dobarganes and Márquez Ruiz, 1996; Gasparoli, 1998)
Due to the complex mixture of compounds originated with different molecular weight and polarity, and to the variable alteration obtained depending of the variables applied, much work remains to be done to complete the present knowledge
The main advantage of fatty acid methyl esters (FAME) model systems is that analysis is carried out directly on the heated sample, overcoming any possible artifact formation during transesterification of TG
Summary
Degradation compounds formed at the high temperature of processes like frying have been extensively studied (Nawar, 1985; Dobarganes and Márquez Ruiz, 1996; Gasparoli, 1998). The determination, known as polar compounds, is the basis of the regulation in some European countries limiting the alteration of used frying fats for human consumption to 25% of polar compounds (Dobarganes and Márquez-Ruiz, 1998) Polar compounds include those formed through thermal, oxidative and hydrolytic reactions and it is possible further quantitation of specific groups of degradation compounds, i.e., polymers, oxidized monomers, diglycerides and fatty acids, by exclusion chromatography, taking advantage of their different molecular weight (Dobarganes etal., 1988; Wolf etal., 1991; Márquez Ruiz etal., 1996). These determinations can be applied directly to the fats and oils or to their simpler derivatives, fatty acid methyl esters (MárquezRuiz ef a/., 1990)
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
