Fat, oxidation products

The consumer generally believes that you only know what you are eating if you prepare the food yourself. However, this is by no means the case. Many new reaction products arise during food preparation. Fatty acids oxidize, proteins fall apart and the fragments react with fat oxidation products, vitamins oxidize to form new compounds, etcetera. The effects on health of most of these new reaction products are largely unknown. The duration of exposure to these new compounds is long, even an entire lifetime. 

The fatty, tallowy-smelling aroma compound 2-pentylpyridin (56), which has been identified in roasted sesame seeds [77], is formed from the reaction of a fat oxidation product, 2,4-decadienal, with ammonia from the degradation of amino acids like glutamine and asparagine [78] (cf. Fig. 3.33). 

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