Structural Determination and Occurrence in Ahiflower Oil of Stearidonic Acid Trans Fatty Acids |
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| Authors: | Pierluigi Delmonte Andrea Milani Shivani Bhangley |
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| Affiliation: | 1. Office of Regulatory Science, Center for Food Safety and Applied Nutrition, US Food and Drug Administration, 5001 Campus Drive, College Park, MD, USA;2. Joint Institute for Food Safety and Applied Nutrition, University of Maryland, 5201 Paint Branch Pkwy, Patapsco Building Suite 2134, College Park, MD, USA |
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| Abstract: | Several marine oils and seed oils on the market contain relevant quantities of stearidonic acid (18:4n‐3, SDA). The formation of 18:4n‐3 trans fatty acids (tFA) during the refining of these oils necessitates the development of a method for their quantification. In this study, 18:4n‐3 was isolated from Ahiflower and isomerized to obtain its 16 geometric isomers. The geometric isomers of 18:4n‐3 were isolated by silver ion HPLC (Ag+‐HPLC) and characterized by partial reduction with hydrazine followed by gas chromatography analysis. The elution order of all 16 isomers was established using a 100 m × 0.25 mm 100% poly(biscyanopropyl siloxane) capillary column and at the elution temperature of 180 °C. The 4 mono‐trans‐18:4n‐3 isomers produced during the refining of oils rich in 18:4n‐3 were chromatographically resolved from each other, but c6,t9,c12,c15‐18:4 coeluted with the tetra‐cis isomer. These 2 fatty acids (FA) were resolved by reducing the separation temperature to 150 °C, but this change caused tetra‐cis‐18:4n‐3 to coelute with t6,c9,c12,c15–18:4. Combining the results from 2 isothermal separations (180 and 150 °C) was necessary to quantify the 4 mono‐trans 18:4n‐3 FA in Ahiflower oil. |
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| Keywords: | Ahiflower Gas chromatography Stearidonic acid Trans fat Trans fatty acids |
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