Mutagenicity of various Japanese foodstuffs treated with nitrite

Mutagenic activities of various Japanese foodstuffs treated with nitrite at pH 4.2 for 10 min (37 degrees C) were tested using Salmonella typhimurium TA 100, TA 1535 and also a streptomycin(SM)-dependent strain of Salmonella typhimurium TA 100. Among 46 common food samples tested, smoked ham, red wines, black teas, soybean pastes and instant coffee powder gave greatly increased numbers of His+ revertants or SM-independent colonies when treated with nitrite. Vegetables, soybean-seasonings and a variety of broths developed no significant mutagenic potential when treated with nitrite. Broiled fish, such as broiled mackerel pike, jack mackerel, tuna and sardine, gave a very slight increase, or often a decrease, in numbers of mutant colonies when treated with nitrite. In order to explore the substances responsible for the development of mutagenic activities in nitrite-treated foodstuffs, several nitrosatable compounds, including polyamines, were investigated. Polyamines are known to react with nitrite to produce several direct-acting mutagens in a short incubation time. Food samples were hydrolyzed with 6 mol/l hydrochloric acid, followed by purification using Amberlite CG-120, and were then submitted to GC analysis, after ethyloxycarbonylation. The high concentration of polyamines which was found in soybean paste could, to some extent, be correlated to the large increase of the mutagenic activities in the foodstuffs treated with nitrite.