Abstract
An “all optical” methodology, including Raman and optical transmission spectroscopy, is presented to study the thermal degradation in edible oils. Oils rich in monounsaturated (MU), polyunsaturated (PU), and saturated (S) fatty acids (FA) were heated above and below their smoke point (∼230 ℃). While the intensity (I) of the identified saturated (C–C, 1440 cm−1) FA Raman marker did not change appreciably, the identified unsaturated (C=C, 1265 cm−1) FA marker decreased in these oils when heated above the smoke point. A Raman parameter, I1265/I1440, designating thermal degradation, is proposed that was found to decrease consistently for the PUFA-rich and MUFA-rich oils when heated above the smoke point, while the SFA-rich oil did not degrade at all over the whole temperature range. An optical transmission marker at 2140 nm was identified that decreased consistently with increased thermal stressing. These markers can be calibrated with the variations in the quantitative iodine value, an industrial benchmark for the degree of unsaturation, for thermally stressed oils.
Keywords
Get full access to this article
View all access options for this article.
References
Supplementary Material
Please find the following supplemental material available below.
For Open Access articles published under a Creative Commons License, all supplemental material carries the same license as the article it is associated with.
For non-Open Access articles published, all supplemental material carries a non-exclusive license, and permission requests for re-use of supplemental material or any part of supplemental material shall be sent directly to the copyright owner as specified in the copyright notice associated with the article.
