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Description
Food fats are primarily triglycerides composed of esterified fatty acids on a glycerol backbone. To measure the fatty acid content of foods, a derivatization reaction is conducted which transfers the fatty acids from glycerol to methanol, forming a fatty acid methyl ester (FAME). FAMES are measured using gas chromatography with flame ionization detection (GC-FID). Free fatty acids in foods are a result of a degradation reactions and are considered a defect. This decreases consumer acceptance and expedites further deterioration which decreases the value of edible oils. The goal of this study was to develop a rapid and sensitive method to simultaneously determine the free and esterified fatty acid content of soybean oil in the same GC-FID run. We were able to selectively derivatize the esterified fatty acids to methyl esters and then detect both free and esterified fatty acids using a free fatty acid phase (FFAP) column. This method was compared to traditional methods of determining acidity, such as titrations, and was verified using thin-layer chromatography. The experimental GC-FID method showed accurate proportions of the five main fatty acids of palmitic, stearic, oleic, linolenic, and linoleic acids that would be expected in soybean oil. Titration standard curves indicated that the free fatty acid content over a series of samples, measured as oleic acid, had a r2 value of 0.999. Standard curves from gas chromatography showed an r2 value of 0.998 of linoleic acid added in the sample. Though there is similarity between the methods, the GC-FID method was able to directly measure linoleic acid which was more favorable for our study. It was noted that quantities less than 0.5% were unable to be detected in this novel method. Future studies would verify that all triglycerides were converted to free fatty acids in the esterification process.
Publication Date
12-9-2021
City
Logan, UT
Keywords
food fats, free fatty acid content, gas chromatography
Disciplines
Nutrition
Recommended Citation
Migliori, Aubreyona, "Determination of Free Fatty Acid and Triglyceride Fatty Acid of Food Fats Using a Rapid Gas Chromatographic Method" (2021). Fall Student Research Symposium 2021. 47.
https://digitalcommons.usu.edu/fsrs2021/47