Crude Fat (Acid Hydrolysis)
Samples containing complexed/bound lipids or fats (e.g. baked and extruded products
and pet foods) require acid to breakdown the fats (e.g. acid hydrolysis) before extraction
and quantifying the total crude fat content. Reference: AOAC 948.15
The term “fat” is a generic term that is also referred to as “lipid” in scientific terms. Fats
or lipids are a very diverse group of chemicals but they have one similarity in that they
are not soluble in water. There are a variety of test methods for fats, but generally the
methods can be broken down into “crude” or total fats. “Crude” methods involve
dissolving the material in a solvent such as ether or hexane and then evaporate the
solvent. The material that remains is called “crude fat.” The result obtained from the
acid hydrolysis method is “Crude Fat.” The results are reported as acid hydrolysis fat to
identify that the appropriate method was applied to the sample matrix. A more detailed
explanation of fatty acids and their determination can be found in another Midwest
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