DPPH Radical Scavenging Activity

DPPH scavenging activity of vegetable oils was tested according to the reference (27), with slight modification. For the Preparation of 2 × 10⁻⁴ M DPPH 95% solution, we used 2 mL of DPPH methanol solution in a test tube, and were mixed with 2 mL of vegetable oils (10, 5, 2.5, 1.25, 0.625 mg/mL). Then were incubated at 25°C in the dark for 30 min. the absorbance A was measured at 517 nm. All experiment was replicated three times. The DPPH· scavenging rate was calculated using the following formula:

DPPH· scavenging rate /% = [1-(Ai-Aj)/A0] × 100

A0 was the absorbance of 2 mL DPPH methanol solution and 2 mL ultrapure water; Ai was the absorbance of 2 mL DPPH methanol solution and 2 mL vegetable oil; Aj was the absorbance of 2 mL ultrapure water and 2 ml vegetable oil.