Crude Fat Analysis Frequently Asked Questions
Answered by: Krista Wincapaw; Senior Analytical Chemist, Macronutrients
Question: When should I request Fat by Acid Hydrolysis?
Answer: This method is used to measure crude fat by acid hydrolysis. The fat is released with hydrochloric acid and is extracted with ethyl ether and hexane. It is then filtered, dried, and gravimetrically measured. This method is used for a variety of foods. There are 3 different procedures depending on the food matrix. One for cheese and cheese products, one for egg and egg products, and one for all other food products except dairy, infant formula, seeds, and nuts.
Question: When should I request Fat by Base Hydrolysis?
Answer: The method uses base (alkaline) hydrolysis to determine the crude fat content. The fat is released with concentrated ammonium hydroxide and is extracted with diethyl ether and petroleum ether. It is then evaporated, dried, and gravimetrically measured. This method is applicable to both liquid and powder infant formulas and dairy products such as milk, ice cream, and yogurt. Other products may be run by request. If you have an infant formula or dairy product that needs testing, this is the appropriate method.
Question: When should I request Fat by Soxhlet?
Answer: This method extracts crude fat by soxhlet. The solvent is refluxed through the sample to remove the fat, which is then dried and determined gravimetrically. This method is used for meat, seeds, nuts, and animal feeds. This can also be used by client request.
Question: What method should I request if I have a cocoa product?
Answer: Eurofins has a specific method that is used for cocoa products. Hydrochloric acid is used on the sample to free fat. It is filtered and rinsed before being extracted by soxhlet for 5 hours with peteroleum ether and finally measured gravimetrically. To request this method, talk with your client services specialist before submitting your samples.
Question: When should I request the Fat by Chloroform/Methanol Extraction?
Answer: Chloroform and methanol are used to extract fat for this method after it is hydrolyzed with enzymes in a hot water bath. This method typically is not as accurate as the other methods. We do not normally recommend this method to determine crude fat but it is available upon request.
See more about Eurofins nutritional testing capabilities HERE.
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