Soxhlet extraction method for measuring fat content

Soxhlet extraction method for measuring fat content

This article mainly discusses how to use Soxhlet to extract the crude fat content of fly-extracted substances, including the used instruments, reagents, experimental principles, experimental operations and so on. I hope that this article will help you more or less, and at the same time help everyone understand what Soxhlet extraction is.

Soxhlet extraction principle: Fat is a lipid compound in which glycerol and fatty acid are combined and can be dissolved in a fat-soluble organic solvent. The gravimetric method used in this experiment utilizes the fact that fats are soluble in fat-soluble solvents, fats are extracted with fat-soluble solvents, and the solvents are weighed after evaporation. The entire extraction process was performed in a Soxhlet extractor. The commonly used fat-soluble solvent is diethyl ether or petroleum ether having a boiling point of 30°C to 60°C. The fat-soluble substances extracted by this method contain fats, phosphoric acid, sterols, aromatic oils, certain pigments, etc. in addition to fats, and are called "crude fats."

The materials, reagents and equipment to be used in the experiment were: whole milk powder, ether (fat soluble solvent) and crude fat analyzer or SZF-06 crude fat analyzer. Ether is a flammable organic solvent, so we should keep the laboratory ventilated during the experiment, while prohibiting any open flame.

Soxhlet extraction has now become the most common laboratory method for determining crude fat content. The Soxhlet extractor is composed of three parts: extraction bottle, extraction tube and condenser (Figure). There are siphon tube and connecting tube on both sides of the extraction tube. All parts of the connection must be tightly leak-proof. During extraction, the sample to be tested is wrapped in a degreasing filter paper bag and placed in an extraction tube. The extraction flask was charged with petroleum ether, the extraction flask was heated, and the petroleum ether was vaporized. The mixture was ascended into the condenser from the connecting tube, and the liquid was dropped into the extraction tube, and the lipid material in the sample was extracted. The level of petroleum ether in the pipe to be extracted reaches a certain height, and the petroleum ether containing crude fat flows into the extraction bottle through the siphon pipe. The petroleum ether that has flowed into the extraction flask continues to be heated and vaporized, rises, and condenses, and is dropped into the extraction tube. This cycle continues until extraction is complete. In the laboratory, the use of a fat extractor (Soxhlet extractor) for extraction and a fat extractor utilize the solvent reflux and siphon principle, so that the solid material is continuously extracted by a pure solvent, which not only saves the leaching efficiency but also has a high efficiency. Therefore, it has been favored by the majority of experimental counterparts.

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