Effect of different processing practices on physicochemical parameters, phenolic compounds, and antioxidant properties of chia seed oils

Alpha-linolenic acid and antioxidant substances (such as tocopherols and polyphenols) are abundant in chia seed oil, which may prevent certain chronic diseases. This study compared the physicochemical parameters, chemical composition and antioxidant properties of black and white chia seed oil extracted by solvent extraction, pressing and supercritical CO₂ extraction. Chia seed oil contained higher levels of polyunsaturated fatty acids, including linoleic acid (18.68%–20.15%) and α-linolenic acid (60.47%–63.68%). Black and white chia seeds and processing methods had significant effects on minor components (tocopherols, total phenols, phytosterols and squalene), oxidative stability and free radical scavenging ability. Compared with other methods, the contents of tocopherols (512.72–603.04 mg/kg), total phenols (35.21–57.75 mgGAE/kg) and phytosterols (5536.69–5956.65 mg/kg) were higher in the pressing method. In addition, 17 individual polyphenols were identified and quantified, among which genistein and gallic acid had higher contents, which were significantly affected by varieties and processing methods. In general, the pressing process may be the best processing method to improve minor components and antioxidant capacity. This study can provide a valuable reference for producing functional foods supplemented with α-linolenic acid.