Many cooking methods involve intense heat with limited availability of oxygen, both favorable conditions for mild browning or pyrolytic (300 ? C) decomposition of the food’s fat and protein components. Pyrolytic decomposition is the breakdown of substances at high temperatures and in the absence of oxygen. Various browning products, polycyclic aromatic hydrocarbons (PAHs), and heterocyclic amines (HCAs) are the major decomposition products of such cooking. On the other hand, baking, using an oven, or deep fat frying (unless the oil is repeatedly used or extremely high temperatures are used) does not produce such decomposition. PAHs are produced during cooking, mainly by pyrolysis of fats, whereas HCAs are pyrolysis products of amino acids, especially tryptophan.