Mutagenic activity of various kinds of cheese on the Ames, rec and umu assays.

Some kinds of cheese were found to be mutagenic when some inhibiting substances were removed through extraction with MeOH-H2O and then treated with ion exchange resin. After this procedure, 16 types of commercial cheese out of 45 types tested showed significant mutagenicity on Salmonella typhimurium TA104, TA102 and TA97 without S9 mix. Almost all of these cheese also showed genotoxicity on the rec assay and the umu assay. The appearance of mutagenicity in these cheeses seemed to be related to the type of aging during the production process; most of the cheeses with high potency belonged to the blue mold and Propionibacteria-type cheeses and only a few belonged to the white mold, Lactobacillus-type or fresh-type cheeses. The substances inhibiting mutagenicity were isolated and identified as long-chain fatty acids.