Effects of heating conditions and additives on the formation of heterocyclic amines with reference to amino-carbolines in a meat juice model system

Common cooked meat and fish products contain heterocyclic amines. Lyophilised bovine meat juice of known composition has been studied in a model system to increase knowledge of the conditions leading to the formation of, especially, the amino-carboline-type heterocyclic amines. The reaction conditions included dry and aqueous heating (at 175°C for 10 min or at 200°C for 30 min) in open and closed vials, with the addition of iron(II)sulphate, creatinine, glucose or tryptophan. After dry-heating the meat juice at 200°C for 30 min, A∝C was clearly identified, together with traces of Trp-P-1 and Trp-P-2. The non-mutagenic β-carbolines harman and norharman formed easily, and the yield increased with increasing temperature, absence of water and the addition of tryptophan. Other heterocyclic amines, e.g. IQx, MeIQx, and PhIP were also identified. Aqueous heating favoured IQx and MeIQx formation, while dry heating favoured PhIP formation.