Relation between Direct Microscopic Method and Resazurin Test for Bacterial Count of Raw Milk

The bacteriological test was carried out by both the direct microscopic method and the resazurin test on raw milk produced in Kanto District and its surroundings. In the resazurin test the colour change intervals was colorimetrically measured in comparison with colour no. 1-no. 4 described in the Standard Colour Table. As the results of our experiment, we found the remarkable correlationship existing between the two methods. The obtained regression formulas are the following: Colour No. 1 X=-0.02045Y+7.749 Colour No. 2 X=-0.01998Y+7.870 Colour No. 3 X=-0.0107Y+7.724 Colour No. 4 X=-0.00874Y+7.704 X means the logarithms of the number of bacteria detected by the direct microscopic method and Y the time (min.) of colour change by the resazurin test.