Formation of Direct-Acting Mutagens in Coffee by Treatment with Nitrite

Abstract

Coffee produced mutagenicity on Salmonella typhimurium TA98 and TA100 without metabolic activation on treatment with nitrite under mildly acidic conditions. The mutagenicity of one cup of instant coffee (1 g of coffee powder in 100 ml of water) treated with 10 mmol nitrite at pH 3 and 37°C for 1 h was estimated to be 3.2 and 8.8×10⁴ His⁺ revertant colonies/plate for TA98 and TA100, respectively. The major mutagen (s) were partially purified by extraction with chloroform and adsorption to blue cotton. The mutagen (s) were separated by high performance liquid chromatography using reverse phase columns, and a mutagenic fraction with a single sharp ultraviolet-absorbing peak was obtained. His⁺ revertant colonies of this fraction per cup of instant coffee equivalent was 488 on TA98 and 300 on TA100 without metabolic activation.