Why Oleic Acid is Used as a Reference for Calculating Free Fatty Acid Content

When quantifying the free fatty acid (FFA) content in a sample, why is oleic acid (C18:1) consistently used as the standard? This practice stems from the unique properties and prevalence of oleic acid, making it a reliable and accurate reference point.

The Role of Oleic Acid in Calculations

Oleic acid is the most abundant monounsaturated fatty acid in natural lipids, constituting up to 40% of total fatty acids in many plant and animal fats. Its prevalence makes it a suitable benchmark for representing the FFA composition of various samples. Moreover, compared to other fatty acids, oleic acid is less susceptible to oxidation, which ensures stability and accuracy in long-term analyses.

Formation and Elongation of Fatty Acids

It is important to note that the journey of fatty acids begins with simple acetic acid (C2), propionic acid (C3), and butyric acid (C4). These shorter-chain fatty acids are then progressively elongated by two carbon atoms at a time. In the human body, this process, known as de novo lipogenesis, particularly leads to the formation of palmitic acid (C16) and stearic acid (C18), which are saturated fatty acids.

Lipid Formation and Desaturation

Variety in fatty acid composition is achieved through desaturation events, which introduce double bonds at specific positions. Many plants produce such desaturated fatty acids, contributing to the formation of omega-3 and omega-6 fatty acids, such as linoleic acid (C18:2, n-6) and α-linolenic acid (C18:3, n-3). These omega fatty acids are crucial for various bodily functions, including inflammation and anti-inflammation.

The Case of Oleic Acid

Oleic acid, with its characteristic double bond at position 9 (C18:1, n-9), is one of the significant omega-9 fatty acids derived from stearic acid. Despite the abundance of longer-chain fatty acids, the importance of oleic acid lies in its common presence and role in inflammatory and cardiovascular health processes.

Conclusion

In conclusion, the consistent use of oleic acid as a reference for FFA calculations is due to its prevalence, reliability, and stability. Understanding the formation, elongation, and desaturation of fatty acids provides insights into the complexity of lipid composition and the importance of oleic acid in various biological functions.

Keywords: free fatty acid, oleic acid, fatty acid composition