In a former publication of this station the results obtained in a study of the clarification of milk with the DeLaval clarifier are presented. The data show: first that commonly, altho by no means constantly, the plates poured from clarified milk contained a larger number of colonies than plates poured from Unclarified milk of the same lot; this was undoubtedly due to a breaking up of the clumps of organisms and should be spoken of as an 'apparent increase since the large number of bacteria in the slime indicates that there was actually an elimination of organisms; second, that there was in every case a decrease in the number of cells during clarification; third, that the clarifier slime contained a large number of bacteria and cells in addition to a variable amount of dirt and sometimes red blood cells. The publication pointed out that, while it must 'be admitted it would be desirable to prevent foreign material from getting into milk, this is impossible for the great bulk of our milk supply because of the increased cost of production and that accordingly clarification of milk followed by efficient pasteurization must be looked upon as a commendable substitution.
Hammer, B. W. and Hauser, A. J.
"Studies on the clarification of milk—II,"
Research Bulletin (Iowa Agriculture and Home Economics Experiment Station): Vol. 4
, Article 1.
Available at: https://lib.dr.iastate.edu/researchbulletin/vol4/iss47/1