The cytochrome c oxidase test for the rapid detection of psychrotrophic bacteria in milk

Abstract

A new, rapid, simple and cheap method for the detection of the predominant psychrotrophic bacteria in raw and pasteurized milks is described, using tetramethyl-p-phenylene-diamine dihydrochloride to detect cytochrome c oxidase which in general is not present in the non-psychrotrophic bacterial milk flora. The test is sensitive to samples containing over 10(4) organisms/ml. Correlation coefficients of 0.92 and 0.84 between dye oxidation and viable counts for pasteurized and raw milk samples, respectively, were found.