Supercritical carbon dioxide extraction of oils from two Torreya grandis varieties seeds and their physicochemical and antioxidant properties

• Parameters of SC-CO2 extract oil from Torreya grandis seeds were optimized.
• The overall quality of two T. grandis varieties seed oil was compared.
• Physicochemical properties, chemical composition of the seed oil were investigated.
• Total phenolic contents and antioxidant activity of the seed oil were investigated.
• T. grandis var. merrillii seed oil is nutrient rich and functional edible oil.

Supercritical carbon dioxide extraction of oil from Torreya grandis seeds was optimized using response surface methodology. Its physicochemical properties, fatty acid composition, total phenolic content and antioxidant activities from two varieties namely T. grandis var. merrillii and T. grandis var. jiulongshanensis were investigated. As results, the maximum oil yield was predicted to be 35.43 g/100 g dry seed using an extraction pressure of 24.98 MPa, temperature of 51.39 °C, extraction duration of 4 h and CO2 flow rate of 15.42 L/h. T. grandis var. merrillii seed oil has better overall quality. Its acid, peroxide, iodine and saponification value were 0.63 mg KOH/g oil, 3.37 m EqO2/Kg, 124.33 mg/100 g oil, 122.86 mg KOH/g oil, respectively. Large proportions of PUFA (59.99%) were found in the oil with linoleic acid (37.81 g/100 g oil) as the main fatty acid. The oil was also found present high content of phenolic compounds (16.9 mg GAE/g) and antioxidant activity in DPPH radical scavenging assay and β-carotene bleaching test (IC50 values of 123.76 ± 0.13 μg/mL and 194.65 ± 0.09 μg/mL, respectively). Our results indicate that T. grandis var. merrillii seeds oil is a good candidate for use as nutrient rich edible oil or ingredients for functional foods.