Effects of Histidine on the Mutagenicity of Casein Tryptic Peptides as Food Ingredient.

Abstract

It has been reported that histidine present in food samples sometimes interfered with the Ames test. We have investigated the amount of histidine in peptides in food samples interfering with the Ames test and examined the mutagenicity of the peptide containing histidine by three other methods which are not interfered in the presence of histidine ; umu test, rec-assay and forward mutation test using Escherichia coli WP2uvrA/pKM101. The number of colony of Salmonella typhimurium TA100 increased depending on the amount of the casein tryptic peptide added in the Ames test. Similar results were obtained by the use of the same amount of histidine as that contained in this peptide. No mutagenicity, however, was detected by the above three other methods. These results indicate that the mutagenicity of foods containing histidine should be examined not only by the Ames test but also by the other tests that are not interfered in the presence of histidine.