Abstract: This study aimed to investigate the effects of processing techniques, including cold pressing, microwave-assisted cold pressing, accelerated solvent extraction, supercritical CO2 extraction, and subcritical fluid extraction on the yield, physicochemical properties, typical lipid concomitants contents, oxidation stability and in vitro antioxidant capacity of flaxseed oil. The results showed that microwave-assisted cold pressing significantly increased the yield of flaxseed oil by 4.3%–10.66% when compared with other techniques (P < 0.05). The physicochemical properties of flaxseed oils produced by the above five methods were different from one another but met the requirements of the Chinese national standard. Supercritical CO2 extraction possessed a better potential in the accumulation of α-linolenic acid in flaxseed oil (54.06%), which was 3.70%–5.31% higher than those of other techniques (P < 0.05). Moreover, the different processing techniques had specific effects on the typical lipid concomitants in flaxseed oil. The highest contents of tocopherols, carotenoids, chlorophyll, flavonoids and phospholipids were found in the flaxseed oils obtained by accelerated solvent extraction and microwave-assisted cold pressing. Subcritical fluid extraction significantly increased the contents of phytosterols in flaxseed oil (429.78 mg/100 g) by 5.07%, 9.34%, 15.57%, and 30.26% in comparison with other techniques (P < 0.05). The flaxseed oil obtained by supercritical CO2 extraction possessed the maximum total phenol content (13.60 mg/100 g), showing a 7.77%–68.53% increase when compared with those prepared by other techniques. Notably, the processing techniques had significant effects on the in vitro antioxidant capacity and oxidation stability of flaxseed oil (P < 0.05). The flaxseed oils prepared by accelerated solvent extraction and microwave-assisted cold pressing showed stronger oxidation stability and 1,1-diphenyl-2-picrylhydrazyl (DPPH) radical scavenging capacity than those obtained by other methods, but the flaxseed oil obtained by supercritical CO2 extraction had a strong iron ion reducing power. These results will provide a theoretical basis for processing various kinds of flaxseed oil.

Key words: oil processing techniques; flaxseed oil; lipid concomitants; antioxidant capacity; oxidation stability