Counting and Sizing Fat Globules Electronically

Abstract

The particle volume and number of fat globules in milk has been successfully determined, using the electrical sensing-zone principle employed in the Coulter Counter. Changes occurring in the size distribution of these fat globules, as affected by the various steps in the production of cream, skim, homogenized milk, and milk concentrate have also been determined. Using raw milk, over 95% by weight of the fat was accounted for by globules with diameters ranging from 1 to 10 μ. Accuracy of the results is attested to by the fact that the fat content of the raw whole milk samples, as calculated from results obtained with the Coulter Counter, agreed with the standard Mojonnier analysis, with a relative error of less than 3%. The globules of raw milk, cream, HTST-pasteurized milk, and milk concentrate were counted with a 30-μ aperture. The skim and homogenized milks contained numerous small globules requiring the use of a 12-μ aperture. Milk samples homogenized at high pressures contained a significant number of globules too small to be counted. © 1966, American Dairy Science Association. All rights reserved.