How is milk fat extracted?

Milk fat can be extracted using a rapid procedure involving freeze-drying, solvent extraction, and microfiltration.

Here's a breakdown of the process, based on the reference provided:

1. Freeze-Drying: The milk sample (typically 1.0 ml) is first freeze-dried. This process removes water, leaving behind a dry residue containing the fat and other solids. The removal of water is crucial for efficient solvent extraction.

2. Solvent Extraction: The freeze-dried milk is then subjected to extraction using a chloroform-methanol solvent mixture. This mixture is effective at dissolving lipids (fats) due to its polarity characteristics. The solvents penetrate the dry residue and dissolve the milk fat.

3. Microfiltration: Finally, the extract containing the milk fat in solution is passed through a Teflon microfilter. This microfiltration step removes any remaining solid particles or non-fat components that may have been co-extracted with the solvent, leading to a purified fat extract. Teflon is chosen as a filter material because it is chemically inert and does not interact with the fat or solvents.

In summary, this method employs a series of steps – freeze-drying to remove water, solvent extraction to dissolve the fat, and microfiltration to purify the final product – to effectively extract and purify milk fat from a small milk sample.