Thermal degradation methyl fatty acid

Other investigators (7-9) have identified a large number of carbonyls from heated fat. The remaining meat aroma components derived by heating lipids are esters, lactones, alkan-2-ones (methyl ketones), benzenoids and other alkylfurans. Several investigators have analyzed volatile compounds formed during thermal degradation of fatty acids (10-12). 

Figure 2.- Total Ion Chromatogram of the thermal degradative products obtained after pyrolysis of the FA isolated from a water-logged peatland, in the absence (Py) and in the presence of TMAH (Py/TMAH). For peak identifications refer to Table I. Contaminants are noted by ( ) and the peaks labeled Cn are fatty acids and C n are fatty acid methyl esters. Reproduced with permission from reference 9. Copyright 1994 Elsevier Science— Netherlands.

Toasting barrels also causes the thermal degradation of certain lipids or fatty acids, forming isomers of methyl-octalactone. This reaction increases in proportion to heating intensity (Table 13.23). The more odoriferous cis isomer, which already predominates in non-toasted wood, represents an even higher proportion of the isomers in toasted oak. This compound is heat sensitive and disappears after 15 minutes (heavy toast). 

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. 

---