A RAPID TEST TO FIND “POTENTIALLY” PSYCHROPHILIC ORGANISMS IN PASTEURIZED DAIRY PRODUCTS

Abstract

The application of the oxidase test to plates prepared for the Standard Plate Count is used as a measure of “potentially” psychrophilic organisms in dairy products. Samples were examined by both the oxidase test and the standard test for psychrophiles, and a statistical analysis shows the tests to be positively correlated. The test is based on the proposition that most problems with psychrophiles can be traced to pseudomonads. These organisms are strongly oxidase-positive and this attribute allows for their differentiation from other bacteria found in food products. The oxidase test consists of flooding the plates used for the total bacterial count with a reagent which causes the strongly oxidase-positive colonies to develop a blue color. This simple test affords a rapid measure of “potentially” psychrophilic spoilage organisms.