Determination of Free Fatty Acids in Edible Fats and Oils

Importance of the Topic

Free fatty acids (FFA) in edible fats and oils serve as a primary measure of hydrolytic degradation, rancidity and overall product quality. Accurate determination of FFA is critical for food safety, shelf‐life prediction and compliance with regulatory standards in food analysis.

Objectives and Study Overview

This application note describes a thermometric titration method using paraformaldehyde as an end‐point indicator to quantify free fatty acids in various edible fats and oils. The aim is to demonstrate method performance, compare results with standard manual titration and highlight advantages of the thermometric approach.

Methodology and Instrumentation

The procedure involves dissolving a weighed oil sample in a 1∶1 mixture of toluene and isopropanol, adding paraformaldehyde and titrating with 0.1 M potassium hydroxide in isopropanol. Key experimental parameters include:

• Titrant delivery rate: 2 mL/min
• Number of exothermic endpoints: 1
• Data smoothing factor: 60
• Stirring speed: setting 5 on an 802 stirrer
• Delay before start: 3 s

Endpoint detection relies on a sharp endothermic response when paraformaldehyde depolymerizes under basic conditions, monitored by a thermometric titrator.

Instrumental Setup

A dedicated thermometric titrator equipped with automatic reagent delivery, temperature sensor and data processing software was used. No color indicators are required, eliminating subjective endpoint interpretation.

Main Results and Discussion

Example determinations on five samples showed excellent agreement between the paraformaldehyde thermometric method and AOCS manual titrations. Reported FFA values (w/w) differed by less than 0.5 % across a range from 0.26 % to 31.7 %. Precision (n = 5) was better than ±0.1 % for all samples. The thermometric method provided rapid, repeatable results with minimal operator influence.

Benefits and Practical Applications

• High throughput analysis in quality control laboratories
• Enhanced reproducibility versus visual or potentiometric endpoints
• Automated data acquisition and processing
• Reduction of hazardous waste by minimizing indicator chemicals

Future Trends and Opportunities

Integration of thermometric titration with inline sampling and process analytical technology (PAT) systems could enable real‐time monitoring of oil quality during refining or storage. Further development may extend the technique to complex lipid matrices, miniaturized sensor arrays and multiplexed analysis platforms.

Conclusion

The paraformaldehyde‐based thermometric titration method offers a robust, accurate and user‐friendly alternative for free fatty acid determination in edible fats and oils. Its strong agreement with reference methods and ease of automation make it well suited for industrial and regulatory laboratories.

References

• M J D Carneiro, M A Feres Júnior and O E S Godinho. Determination of the acidity of oils using paraformaldehyde as a thermometric end‐point indicator. J Braz Chem Soc 13 (5) 692–694 (2002)