Wednesday, 12 April 2017

Determination of Crude Lipid

Crude fat is the term used to refer the crude mixture of fat- soluble material present in a sample. It is also known as the ether extract or the free lipid content and is the traditional measure of fat in food products. The common approach for total crude fat determination is based on the solubility of lipids in non-polar organic solvents such as hexane, diethyl ether, acetone.

Apparatus: round bottom flask, soxhlet extractor, condenser, host, heating mantle
Reagent used: diethyl ether

  • The apparatus for extraction is set up and few granules of antibombing is added  to the round bottom flask and about 100ml of diethyl ether is added to the round bottom flask.
  • 55 g of the pretreated sample is folded in a plain sheet and turned into the extractor. This is to prevent the sample from touching the walls of the extractor. The various points of attachment is greased to prevent evaporation. Glass wool is  used  to lag  the end of the condenser.
  • The sample is heated until the colour of the solvent passing through the evaporating arm turns colourless. Then the lipid has completely been extracted.

Distillation of the extracted sample
  • The purpose of distillation is to separate the solvent (diethyl ether) from the lipid that has been extracted.
  • The apparatus for distillation is set up. The sample extract is distilled until it turns gel like and the sample is placed in a desiccator to completely dry
  • After drying, the weight of the round bottom flask containing the sample is taken and then washed. The weight of the washed flask is also taken.
  • The weight of the empty flask is subtracted from the weight of the flask containing the crude fat.

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