Oils and Fats are the triglycerides of fatty acids in which one molecule of glycerol has combined with three molecules of long chain fatty acids with the Elimination of water. In addition to triglycerides, the oils and fats may contain a total of 2% free fatty acids, and sterols, phospholipids coloring material and hydrocarbons.
An oil is a liquid at the ordinary temperature whereas a fat is usually a solid.
Extraction is a physical separation method used when the substance to be extracted is soluble in a solvent. The more soluble the substance the faster the extraction process.
There are two methods of separation.
Chemical separation results after a chemical separation. Precipitation is an example of a chemical separation. Physical separation results from the use of mechanical methods. Extraction and volatilization are examples of physical separation.
Solvent Extraction is a physical separation using a separating funnel. The liquid extraction method used water and non-miscible organic solvent. The substance to the extracted (Solute) on use have a greater affinity for the organic solvent than the water.
This is expressed as the distribution coefficient K where
K = CS/CW
CS - Solubility of the Solute in Solvent.
CW - Solubility in Water.
K must have a high numeric value for an efficient extraction to be completed.
In 1879 German Chemist, Franz Von Soxhlet developed the technology for the first time. The condensed solvent is continually contacting the sample, the solutes affinity for the solvent will continue until the extraction is complete.
The solvent flask now contains solvent as soluble. In gravimetric analysis the solvent is driven off. The solute must be removed and weighed for analytical measurement.