Triglycerides thermally oxidized

Soybean oil is an abundant annually renewable resource. It is composed of triglycerides with long chain saturated and unsaturated hitty acids. The presence of these unsaturated tty acids results in poor oxidative stability. However, this enhanced reactivity also allows for chemical modification to introduce new functionalities to the oil. A novel single-step catalytic ozonolysis and in-situ reaction will be described. The reaction proceeds rapidly and efficiently at room temperature in the absence of solvents. The catalytic ozonolysis reaction has been used to reduce the unsaturation in soybean oil, and successfiiliy prepare a number of potentially useful materials such as bio-lubricants with good thermal/oxidative stability, bio-diesel with thermal properties comparable to that of Diesel Fuel 2, and bio-plastic intermediates such as polyols, polyesters, and polyamides. This new class of soy-based materials is competitive both in cost and performance to petroleum based nuterials and offers the added advantage of being environmentally friendly and sustainable. 

Zeman and Scharmann (57) reported the presence of 0.3% nonpolar dimers composed of diunsaturated bicyclic and tetraunsaturated acyclic structures in peanut oil subjected to thermal and oxidative action. Perrin et al. (58) analyzed samples from two different peanut and sunflower oils oxidized by deep fat frying to a stable foam formation. They reported the presence of dimers at levels between 12.1 % and 12.9% of the oxidized mixtures. Peanut oil oxidized by deep fat frying before and after stable foam formation yielded 7.8% and 14% dimers, respectively. Gere et al. (59) reported nonpolar and polar dimeric triglycerides in sunflower oil used in deep fat frying. 

As shown in Figure 2-23, oil breakdown during frying can be caused by oxidation and thermal alteration. Oxidation can result in the formation of oxidized monomeric, dimeric, and oligomeric triglycerides as well as volatile compounds including aldehydes, ketones, alcohols, and hydrocarbons. In addition, oxidized sterols may be formed. Thermal degra-... 

Fats or raw materials that serve as a source for fatty acids are frequently employed in process flavourings. During the flavour reaction, thermal peroxidation of lipids such as triglycerides, fatty acids and phospholipids occurs. This non-enzymatic lipid oxidation, also called autoxidation, leads to a very complex mixture of reaction products, and has to be regarded separately from the enzymatic lipid oxidation which occurs at low temperature and is catalysed by lipoxygenases. 

Numerous compounds result from these reactions. For example. Table 3.45 lists a series of aldehydes and methyl ketones derived preferentially from tristearin. Both classes of compounds are also formed by thermal degradation of free fatty acids. These acids are formed by triglyceride hydrolysis or by the oxidation of aldehydes. 

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