Photomicrographs of Milk Protein Particles

Abstract

Ultracentrifugation studies have shown that protein particles exist in normal untreated milk in a range of sizes with sedimentation constants of 180 to 4950 x 10-13. When whole milks were heated to sterilization temperatures, sedimentation constants of the slowest sedimenting fraction increased to 1000-3000 x 10-13. Similar constants for reconstituted sterile concentrated milks were 30,000 or higher. Particles with a sedimentation constant of 30,000^[long dash][long dash]should have a diameter of 0.7 [mu] calculated by the equation [image] and should be microscopically visible. Photomicrographs were made before and after concentration and sterilization by ultra high temperatures confirming the change in particle size.