Observation of fine structure in casein micelles by means of high resolution electron microscopy

Abstract

For fabrication purpose an argon ion beam is produced in ion source, accelerated through a high vacuum chamber and directed with final focusing to impinge on a target.In the biological field we have utilized ion beam sputtering to examine the sub-micelles structure of casein micelles in demineralized skimmed milk. For this purpose we employed sputtering to etch the samples and to shadow the specimens. Casein micelles are remarkably stable both in fresh milk and in properly processed concentrated milk products where they are aggregated by calcium phosphate bonds.Raw skimmed milk, electrodialysis demineralized by using ion exchange membranes were examined. The samples were fixed in 2.45%cacodylate buffered glutaraldehyde at pH 5.9-6.8 for 2 -4 hr and post-fixed in 2% cacodylate buffered osmium tetroxide at the same pH for 2 hr. After being diluted with distilled water, the samples were picked up on microgrids.