Mutagenicity of nitrite-treated soy sauce in Chinese hamster V79 cells.

Mutagenicity of 4 kinds of Japanese soy sauce and tyramine, which is a precursor of a mutagen (3-diazotyramine) and present in soy sauce, after nitrite treatment under a yellow lamp was studied in Chinese hamster V79 cells with 6-thioguanine (TG) as a selective marker. The frequencies of mutation caused by nitrite-treated samples of soy sauce increased in the V79 cells in a dose-dependent manner. Four kinds of nitrite-treated soy sauce induced 139 to 473 TG-resistant mutants per 10(5) clonable cells per milliliter of soy sauce equivalent in the cells. Nitrite-treated tyramine was also mutagenic for the cells; it induced 8.6, 13.3, and 18.3 TG-resistant mutants per 10(5) clonable cells at concentrations of 20 micrograms, 56 micrograms, and 112 micrograms, respectively.