Catalase Test for Abnormal Milk. I. Techniques and Factors Affecting the Test

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Abstract
Techniques for testing milk for catalase activity and to determine the effects of certain experimental variables on the reaction were compared. Calibrated centrifuge tubes with outlest of straight glass tubing were most satisfactory in the inverted tube test. Increase in substrate concentration above 1 ml 3% H2O2 did not significantly increase O2 production at room temperature, but significantly more O2 was produced from 2 ml H2O2 below 20 C. The variance was lower with 2 ml H2O2. The reaction was slower but more O2 was produced at lower temperatures. The test could be read at 3 hr. and minor temperature variations had little effect at room temperature. Storing milk at 5 C did not affect catalase activity for 3 days unless there was appreciable bacterial growth. Results of the inverted tube method were closely related to those of the Warburg procedure, and the enzyme-product relationship was linear between 20 and 60% O2 production.