What Are Free Fatty Acids (FFA)? Complete Explanation for Chemists

Free Fatty Acids (FFAs) are an important quality parameter in oils, fats, and many industrial and food products. Whether you work in a chemical lab, oil refinery, or food industry, understanding FFAs helps you determine the freshness, stability, and suitability of oils for further processing.

In this blog post, we will explore:

1. What are fatty acids and FFAs?
2. Why FFAs increase in oils
3. Hydrolysis & oxidation processes
4. How FFAs are determined in the laboratory
5. Chemical reactions involved

What Are Fatty Acids?

Fatty acids are the building blocks of fats (lipids). They consist of:

• A long chain of carbon and hydrogen atoms

• A functional group – carboxyl group (–COOH)

General structure:
R–COOH

Detailed form:
CH₃–(CH₂)ₙ–COOH

Examples:

• Stearic acid (C₁₇H₃₅COOH) – saturated fatty acid

• Oleic acid (C₁₇H₃₃COOH) – unsaturated fatty acid

Normally, these fatty acids are bound to glycerol in the form of triglycerides. These are not free.

What Are Free Fatty Acids (FFAs)?

Free Fatty Acids are those fatty acids that are not attached to glycerol or any other molecule. They are “free” and present in oils due to natural or chemical breakdown processes.

High FFA means:
❌ Poor quality oil
❌ Higher chances of rancidity
❌ Decrease in shelf life

Why Do FFAs Increase?

FFAs usually increase because of two major reactions:

1. Hydrolysis of Triglycerides

Hydrolysis = Breakdown of triglycerides in the presence of water.

Reaction:
Triglyceride + 3H₂O → Glycerol + 3 Free Fatty Acids

Reasons:

• Moisture

• Heat

• Poor storage conditions

Hydrolysis process:

• Water breaks ester bonds

• Glycerol is released

• Fatty acids separate and become free

Heat acts as a catalyst and speeds up the reaction.

2. Oxidation of Oils

Oxidation occurs when oxygen reacts with fats, especially with unsaturated fatty acids.

Reaction:
Fatty Acid + O₂ → Oxidized Products + Free Fatty Acids

Causes of oxidation:

• Presence of oxygen

• Light exposure (UV)

• Heat

• Metal catalysts

Products formed during oxidation:

• Free fatty acids

• Peroxides & hydroperoxides

• Aldehydes

• Ketones

Hydroperoxides break down easily and release FFAs.

Laboratory Determination of FFA (Titration Method)

FFA analysis is commonly done by acid–base titration.

1. Sample Preparation

Steps:

1. Weigh 2–10g of oil sample

2. Dissolve in a neutral solvent (isopropanol or ethanol)

3. Add phenolphthalein indicator

This makes the oil ready for titration.

2. Titration with NaOH

The FFAs (R–COOH) react with the base (NaOH).

Reaction:
R–COOH + NaOH → R–COONa (soap) + H₂O

Procedure:

• Prepare 0.1M NaOH solution

• Titrate slowly while stirring

• Endpoint is when solution turns light pink

This indicates all FFAs have been neutralized.

FFA Calculation Formula

The FFA is usually expressed as a percentage of oleic acid:

$$FFA(\%) = \frac{V_{\text{NaOH}} \times M_{\text{NaOH}} \times 282.47}{\text{Weight of oil (g)} \times 1000} \times 100$$

Where:

• 282.47 g/mol = molecular weight of oleic acid

Neutralization Reaction – What Happens?

When NaOH neutralizes FFAs:

Products formed:

✔ Soap (R–COONa)
✔ Water (H₂O)

This simple reaction forms the basis of FFA determination.

Conclusion

Free Fatty Acid (FFA) testing is essential for checking the quality and stability of oils. Proper handling, storage, and protection from heat, moisture, and oxygen can significantly reduce FFA formation.

Whether you're involved in QA/QC, food processing, or chemical industries, understanding FFAs helps ensure better control of product quality.