Standardizing the Babcock Test for Milk by Increasing the Volume of the Sample and Eliminating the Meniscus on the Fat Column

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Abstract
In the Babcock test for milk, the meniscus on top of the fat column is included. Because of its indefinite dimensions as viewed by different technicians, the meniscus has been the source of considerable variation in reading tests. The temp. of sampling milk for the test has not been consistently standardized under commercial conditions. For example, the A.O.A.C. specifies a sampling temp. of 15 to 20[degree]C for milk, and if lumps of cream are not dispersed, the sample should be warmed to about 38[degree]C, mixed thoroughly and finally cooled to 20[degree]C before pipetting. As composite samples are kept in most plants, it is necessary to heat them to about 38[degree]C to obtain a homogeneous mixture. Cooling preserved samples back to 20[degree]C is likely to result in partial churning of the fat emulsion when the samples are mixed immediately before being pipetted into test bottles. Consequently, the tests of partially churned samples are lowered because clusters of fat adhere to the inner surface of the pipette. The simplest approach to standardizing the Babcock test in order to obtain agreement with the ether extraction method is to increase the volume of the sample of milk to 18.36 g., to eliminate the meniscus in the fat column, and to sample both preserved and unpreserved milk at 35[degree] to 38[degree]C. Standardizing the Babcock test by this procedure is simple, fundamentally sound and accurate as indicated by comparisons with the Mojonnier method on 135 samples of unpreserved milk by 5 experienced laboratory technicians.