Application of mutagenicity test for milk.

Mutagenic activity in milk and milk products was tested by the Salmonella mammalian-microsome mutagenicity test (Ames test). Salmonella mutants susceptible to base-pair substitution and frame-shift mutagens gave positive results with heat-sterilized milk, particularly after activation by the S-9 fraction of microsomes. Maximum increase of His+ revertants was more than twice the spontaneous increase. The chemical specification of the mutagenic activity was not yet defined, but it was present in the chloroform extract of milk.