Chemistry, formation and occurrence of genotoxic heterocyclic aromatic amines in fried products

Heterocyclic amines (HAs) are formed during heating of meat or fish. The precursors necessary for formation of these heterocyclic amines are amino acids that react with carbohydrates and creatinine. Creatinine is needed for the formation of polar amines with an imidazo-quinoline or an imidazo-quinoxaline structure. For the formation of the non-polar amines no creatinine is needed. At temperatures of above 150 C these substances are formed in the low ppb range. However, when the temperature is increased or the heating time is prolonged the concentration of the amines can reach levels of above 100 ppb. Heterocyclic amines are mutagenic in bacterial and animal test systems and carcinogenic in rodents. As the heterocyclic amines are not mutagenic by themselves they have to be activated with cytochrome P450 enzymes and N-acetyl-transferases or sulfotransferases. Epidemiological studies have revealed that the cancer risk is strongly associated with the uptake of thoroughly roasted meat in which the heterocyclic amines occur. As these substances are formed inherently, measures have to be taken to reduce the formation in meat or fish during cooking. These measures range from changing cooking habits to use with additives or breeding of animals with a genetically determined lower HA forming capability of the meat.