Food Structure

Electron Microscopic Localization of Solvent-Extractable Fat in Agglomerated Spray-Dried Whole Milk Powder Particles

Creative Commons License

Creative Commons Attribution 4.0 License
This work is licensed under a Creative Commons Attribution 4.0 License.


An agglomerated spray-dried whole milk powder has been studied by electron microscopy before and after extracting approximately 10% of total fat with petroleum ether at 25°C for l hour. The powder samples were suspended in polyethylene glycol, cryofixed and further prepared by the freeze-frac turing technique. These studies demonstrate that the solvent-extractable fat (the so-called 'free fat') consists partly of surface fat and partly of fat extracted from fat globules within the powder particles. The spatial distribution of such solvent accessible fat globules appeared to be rather uneven, i.e. whereas certain limited volumes within a powder particle showed an almost complete extraction, others remained unaffected. There were no indications that fat globules near the periphery of the powder particles were more accessible for the solvent than those in the interior of the particles. The results of this study generally confirm the model by Burna for the distribution of 'free fat' in dried milk.

This document is currently not available here.