Submitted to: Lipid Technology
Publication Type: Review Article
Publication Acceptance Date: 3/13/2013
Publication Date: 4/18/2013
Citation: Doll, K.M., Hwang, H. 2013. Thermal modification of vegetable oils. Lipid Technology. 25(4):83-85.
Interpretive Summary: A recent ARS publication on the study of a product produced by heating soybean oil has drawn the attention of a leading trade publication. In this article, the chemical structure of the product from the decades old process is studied using modern methods. This current publication highlights the findings of the primary publication article, and condenses them into a shorter and more easily read version. Additionally, the analytical methods are extended to discover the key to understanding the oxidation of cooking oils. This is a problem that, try as we might, remains unsolved. This research will bring light to both the cooking industry, as well as those who want to benefit from industrial formulations of the thermally modified soybean oil.
Technical Abstract: This article reviews some literature, both old and recent, involving the hypothesis that the Diels-Alder reaction is operative in the thermal polymerization of vegetable oil. Both triacylglycerol oils and methyl esters are used to show that this mechanism is unlikely to be a significant contributor in route to the reaction products. Systems where the Diels-Alder reaction is impossible, by any account, such as the polymerization of methyl oleate under oxygen, to those where it is invited, such as the polymerization of conjugated methyl oleate, are discussed. The most telling data is the spectroscopy of products which definitively show the lack of six-membered ring structures which would be required by a Diels-Alder reaction. Lack of correct substrates, conformations, and electron withdrawing ability are also discussed.