Chemicals
The refined soybean seed oil was obtained by a local oil refining factory (Aliagolestan Co., Gorgan, Iran). Antioxidant compounds including gallic acid, methyl gallate, propyl gallate, octyl gallate, dodecyl gallate, and stearyl gallate of analytical grade (Fig. 1) were supplied from Sigma-Aldrich (St. Louis, MO). All the other solvents and chemicals applied in this research were purchased from Sigma-Aldrich (St. Louis, MO) and Merck (Darmstadt, Germany).