Oxidative stability and fatty acid profile of vegetable oils from the Estonian market

• Oxidative stability was measured using the RSSOT method. • Oils rich in MUFA had the longest induction period. • Cluster analysis grouped oils into four categories by FA profile and stability. • Regression analysis identified key fatty acids affecting oxidative stability. The fatty acid (FA) composition of vegetable oils (VOs) plays a crucial role in determining their oxidative stability. In this study, 80 oil samples purchased from the Estonian market were analysed to examine the relationship between FA profiles and oxidative stability. FAs were quantified by gas chromatography with a flame ionization detector using a highly polar capillary column, while oxidative stability was assessed via a rapid small-scale oxidation test by measuring the induction period (IP). The IP varied widely among samples, ranging from 13.31 ± 0.70 min for linseed oil to 87.68 ± 0.51 min for cold-pressed high-oleic sunflower oil (HOSO). Saturated fatty acids (SFAs) ranged from 3.33 ± 0.31% to 21.21 ± 0.50% , monounsaturated fatty acids (MUFA) from 15.33 ± 0.58% to 84.11 ± 1.19%, and polyunsaturated fatty acids (PUFA) from 3.70 ± 0.57% to 69.83 ± 0.76%. Descriptive analysis revealed that oils rich in MUFA (especially HOSO) exhibited the longest IP, whereas linseed oil, with a high PUFA content, showed the shortest IP. Principal component and cluster analyses further classified the oils into four distinct groups based on their FA composition and IP characteristics. These findings provide insights to improve oil shelf life and food quality. IP increased with MUFA – particularly oleic acid (C18:1n-9c) – and decreased with PUFA and the PUFA/SFA ratio (all p<0.001); SFA showed no association. Stepwise regression identified C18:1n-9c as the strongest positive predictor of log(IP) (p<0.001). The results indicate considerable variability in the quality of VOs on the Estonian market, highlighting the importance of label transparency. This study provides the first comprehensive evaluation of the FA composition and oxidative stability of a wide range of VOs available on the Estonian market. By combining chromatographic profiling with chemometric analysis, the work not only identifies key quality differences among oils but also demonstrates how oxidative stability is closely linked with FA composition. These findings emphasize the importance of selecting oils with higher oxidative stability for both consumers and the food industry, thereby contributing to improved dietary recommendations and storage guidelines.