When extracting lipids or fats from foods, both the method as well as the solvents chosen to perform a complete, or close to complete extraction are important. If these two elements are not taken into consideration, the extraction may not be complete, or the extract may contain a large quantity of undesired impurities. The natural fats and oil are mixtures of glycerides of fatty acids. Fats and oils are naturally occurring organic compounds which belong to a large group of water insoluble substances called lipids. Lipids are relatively non-polar molecules, they can be pulled out of a sample using relatively non-polar solvents. With a non-polar solvent, only non-polar molecules in the sample dissolve while polar ones do not. A solution to the problem of extracting "trapped lipids" is to use an extraction procedure such as the soxhlet that will help break up the polar barriers and allow the solvent to reach the non-polar compounds and extract them. In this experiment, soxhlet extraction was used. Soxhlet extraction is an extraction method that uses chemical solvents. Oils from the algae are extracted through repeated washing, or percolation, with an organic solvent such as hexane or petroleum ether, under reflux in a special glassware. Copra, dried kernel of the coconut, was the sample used. Often though, the sample must be ground and prepared prior to the extraction procedure in order to break up the cell membranes and other structures that would make extraction difficult. In this experiment, petroleum ether was used as the solvent due to its low boiling point, relatively non-toxic nature (when compared to chloroform or methanol), and of course because it is quite non-polar. When talking about ether, two kinds can be used in lipid extraction: anhydrous diethyl ether CH3CH2OCH2CH3 and petroleum ether, which is a mixture of pentane (CH3CH2CH2CH2CH3) and hexane (CH3CH2CH2CH2CH2CH3). Petroleum ether is more non-polar, cheaper and less flammable than...
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