Supercritical carbon dioxide extraction and conventional extraction of chia seed oils: chemical composition and lipid oxidation

Abstract

Chia seed (Salvia Hispanica L.) oil was obtained by supercritical CO₂ (SC-CO₂) extraction and conventional solvent extraction (CSE). The seeds were from Brazil (seeds and stabilized flour), Sweden and the Netherlands. The processing parameters related to chia oil extraction using different seeds countries have not been studied yet. The chia oils were characterized with regard to fatty acid (FA) composition, antioxidant properties (ABTS, DPPH and FRAP), Peroxide Index (PI), TBARS (thiobarbituric acid reactive substances) and tocopherol. The yield of the extracted oil was 25.7-32.2% with CSE and 27.8-31.8% by SC-CO₂. The oils mainly contained unsaturated fatty acids (84.6-88.1%), the total concentration was similar between the different extraction methods. The ratio of omega-6/omega-3 fatty acid was 0.40, being markedly better than that reported for other vegetable oils. The SC-CO₂ extracted oil showed greater antioxidant capacity compared with CSE extracted oil, whereas no significant differences were observed for levels of TBARS and PI. The total tocopherol content ranged from 141 to 601 mg/Kg and consisted mainly of gamma-tocopherol (88%). This study reveals that chia seed oil could be an interesting functional food ingredient. We also propose that SC-CO₂ extraction is a better option than CSE for extraction of chia seed oil as it does not require use of organic solvents and is more environmentally friendly.