Determination of Crude Fat Analysis in Food samples


What is Crude Fat?

Crude fat is the term used to refer to the crude mixture of fat-soluble material present in a sample. The traditional technique for determining the amount of fat in food products is known as crude fat, also known as ether extract or free lipid content. Triglycerides, diglycerides, monoglycerides, phospholipids, steroids, free fatty acids, fat-soluble vitamins, carotene pigments, chlorophyll, and other substances may be included in the lipid materials. The process of crude fat analysis in food samples will be studied in this article.

Crude fat is a term used to describe the total amount of fat present in a food or feed sample. By extracting the fat from the sample using a solvent like petroleum ether or hexane, one may calculate the lipid content of the sample. The result is expressed as a percentage of the initial sample weight after the extracted fat is dried and weighed.

Function of Crude Fat

One of the main functions of crude fat in the body is to provide energy. With more than twice as much energy per gram as proteins and carbohydrates, fat is a highly concentrated source of energy. Crude fat helps with the transport and absorption of fat-soluble vitamins such vitamins A, D, E, and K in addition to providing energy.

Various dietary sources, such as meat, fish, dairy products, nuts and seeds, cooking oils, and avocados, include crude fat. The type of animal or plant, the amount of the animal or plant utilized, and the process of preparation are only a few examples of the factors that might affect the amount of crude fat in a food product.

In the food and feed industries, crude fat analysis is frequently used to assess a product’s nutritional value. Although fat is an essential supply of energy and vital fatty acids, consuming too much of it can result in health issues including obesity and heart disease. As a result, it is important to understand the crude fat content of a food or feed sample for both nutritional and health reasons.

Fat content analysis
Fat content analysis

Principle of crude Fat content Analysis in Food samples

The principle of crude fat analysis in food is to determine the total amount of fat present in a sample by extracting it using a solvent and then measuring the weight of the extracted fat. The analysis is based on the principle that fats are soluble in organic solvents such as petroleum ether or hexane. while other components of the food sample, such as proteins and carbohydrates, are not soluble in these solvents.

The food sample is combined with the solvent and agitated during the crude fat analysis in order to dissolve the fats and oils while leaving the other ingredients in the sample. The solvent is then removed from the mixture, leaving the extracted fat left after filtering to get rid of any solid components. The proportion of fat in the original food sample is then determined using the weight of the extracted fat.

The crude fat analysis consists of all forms of lipids present in the sample, including free fatty acids, phospholipids, and glycolipids. It does not distinguish between other types of fats, such as saturated, unsaturated, or trans fats.

Apparatus and Equipment

  • Balance Machine
  • Filter Paper
  • Cellulose Thimble
  • Fat Bottom Flask 
  • Hot Air Oven
  • Soxhlet Apparatus

Procedure of Crude Fat Content Analysis in Food sample


Thimble Preparation

  • Make a thimble with the help of filter paper.
  • Place the thimble on balance machine.
  • Tare the weight of the thimble.


Sample Preparation

  • Take out the thimble from the balance machine and take about 5g of sample into the thimble.
  • Take a note of sample weight.
  • Place a cotton into the thimble in a way that covers the sample and fold the thimble to enclose the sample.
  • Take a dried and clean flat bottom flask and take a weight of the flask placing on balance machine.


Fat Extraction

  • Set up the Soxhlet extraction unit placing the sample it.
  • Add sufficient amount of n-Hexane 
  • Run the water through the condenser of the Soxhlet extraction.
  • Turn on the power and run the Soxhlet extraction.
  • 6hrs later, take out the thimble and collect the wastage n-hexane.
  • Collect rest of then- Hexane from the flask by condensation.
  • Rotate the flask to evaporate the excess n-Hexane from it.


Taking Final weight

  •  Place the flask inside the oven to remove moisture and hexane at 110°C for 30min.
  • After 3omin, take out the dried flask and place and cool in desiccator.
  • After cooling, take the weight of flask with fat.



Crude Fat %:  ´100


  • Ws is the weight of sample
  • W2 is the weight of flask with fat
  • W1 is the weight of flask

Application of crude fat analysis in food samples

Crude fat has various applications in different industries. Here are some of the common applications of crude fat:

Food Industry: There are several reasons why it’s crucial to measure crude fat content. To give information about the energy content and possible effects on health, for instance, it is used in the nutritional labeling of food goods. Additionally, as it affects the product’s texture, flavor, and overall quality, crude fat content plays a significant role in food product formulation.

Animal Nutrition: Crude fat, a nutrient that is essential to cattle and pets, is added to animal feed to increase its calorie density and palatability. Crude fat also provides essential fatty acids that are important for optimal growth and health.

Production of Biofuels: Biodiesel is a renewable and environmentally friendly fuel that is made from crude fat that comes from both plant and animal sources.

Cosmetics Industry: Crude fat is used in the cosmetics industry to make a variety of products that nourish and moisturize the skin, including soaps, lotions, and creams.

Pharmaceutical Industry: To help dissolve, suspend, or stabilize active components, crude fat is utilized as an excipient or carrier in pharmaceutical formulations.

Industrial Applications: Crude fat is a raw material that is used to make lubricants, soaps, candles, and other products.

Limitation of crude fat content

While crude fat content provides valuable information about the amount of fat present in a sample, there are some limitations to this measurement. The following are some limitations on crude fat content:

  • Incomplete extraction: The method of extraction utilized affects the accuracy of the measurement of crude fat content. An incomplete extraction may result in a lower estimate of the actual fat content.
  • Lack of specificity: Crude fat content assesses the overall amount of fat in a sample but does not reveal the types of fats that are present. Determining the particular types of fats present is essential since various forms of fat have varied health effects.
  • Variation in fat content: The fat content of a food product can vary depending on various factors, including the animal or plant species, the part of the animal or plant used, and the method of preparation. This can lead to variability in the crude fat content measurement.
  • Interference from non-fat components: Some non-fat components in a sample, such proteins and carbohydrates, might affect the measurement of crude fat level and produce inaccurate results.

The determination of crude fat content involves extracting the total lipid content from a sample using various methods, such as Soxhlet extraction, acid hydrolysis, or solvent extraction. For calculating the percentage of crude fat content, the recovered lipid is dried and weighed. The measurement of crude fat content offers essential information about the amount of fat present in food items, animal feed, and industrial processes, which can affect the final product’s quality, nutritional value, and energy density. Although crude fat content has disadvantages including partial extraction and a lack of specificity, it is nevertheless a helpful gauge for a variety of industries and applications.

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Sarmila K C

Welcome to The Science Notes! I'm Sarmila K C, a science writer with a background in Food Technology. My mission is to simplify complex scientific topics and make them accessible to everyone. I cover the various topics of science and explain them with clear, accurate information.

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