Composition and oxidative stability of oil from Salvia hispanica L. seeds in relation to extraction method

Abstract

This study evaluated the influence of the extraction method on the composition, quality and oxidation stability of chia seed oil. Commercial chia seeds were purchased from a local market and oils were obtained using various methods: Classical Soxhlet extraction using hexane and acetone, supercritical fluid extraction with CO2 at 70 and 90°C, and screw‐pressing from native seeds (cold process), and from seeds conditioned at 110°C (hot process). The oils were characterized by their contents of sterols, tocochromanols, phenolic compounds, carotenoids and squalene, acid and peroxide values and induction times. It was found that the method of obtaining oil had an influence on the extraction of components and oxidative stability. The most favorable method was classical extraction with acetone. This solvent was the most effective in the extraction of total lipids and bioactive components, especially phenolic compounds and carotenoids. The content of these components was highly correlated with induction time. The recovery of oil was generally lower by pressing than by extraction methods and the content of sterols and phenolic compounds was also reduced. In turn, fluid extraction at 70°C was effective in the extraction of squalene and the quality of oil extracted by this method was comparable to cold pressed oil.Practical applications: Chia seeds contain a large amount of oil (from 25 to 35%), which is rich in polyunsaturated fatty acids, mainly α‐linolenic and linoleic acids, with share of ca. 60–67% and 20%, respectively. The high content of PUFA makes this oil very susceptible to oxidation. The seeds are also abundant in many phytochemicals (sterols, tocopherols, squalene, waxes, carotenoids, and phenolics), but their extractivity to the oil depends on the processing conditions. In the study, we evaluated the composition and stability of chia seed oils obtained by classical solvent extraction, supercritical fluid extraction with CO2 and screw‐pressing. It was shown that the most favorable method was the extraction with acetone. This solvent was the most effective in extraction of total lipids and bioactive components, especially phenolic compounds and carotenoids. Oil obtained by extraction with acetone was additionally characterized by the highest oxidative stability. This information may be of support to producers for obtaining chia oil more stable and with better nutritional and nutraceutical properties.Oil obtained by extraction with acetone is very different from other oils considering the quality, stability, and contents of bioactive compounds.