A MODIFICATION OF THE ALCOHOL TEST AS AN INDEX OF THE BACTERIAL COUNT AND KEEPING QUALITY OF MILK

Abstract

This test is claimed to be a more satisfactory method of determining the approximate bacterial count and keeping quality of a sample of milk than the reductase-fermentation test. From the experiments carried out it was concluded that the following modifications in the alcohol test give best results (1) A preliminary incubation period of 9 hrs. at 37[degree]C; (2) use of 83% (by volume) neutral alcohol containing 0.2% methyl red. To carry out the test, 40 cc. of milk is poured into a sterile boiling tube fitted with a rubber stopper and incubated 9 hrs. at 37[degree]C. The milk is then cooled by immersion of the tube in water, shaken vigorously and 2 cc. poured into a test tube. To this is added 2 cc. of 83% methyl red alcohol and the color and type of precipitate noted and compared with a chart. Approximate keeping quality and bacterial count is determined by color and type of precipitate produced.