and soybean seeds) were frozen under liquid nitrogen and ground with pestle and mortar to a fine powder. A volume of solvent (1 ml/g) was added, and the suspension was homogenized, transferred to polypropylene tubes, and shaken for 1 h at room temperature in the dark. When required, the extraction solvent was supplemented with BHT (1 mg/ ml) or spiked with a-, g-, and d-tocopherol or the internal standard a-tocopherol acetate. After centrifugation at 10,000g for 15 min, the supernatant was transferred to new tubes. The pellet was resuspended and homogenized in another volume of solvent and centrifuged once more. The supernatant was combined with the first extract and kept at 4°C until immediate use in HPLC or spectrophotometric determinations. The rest of the samples were subjected to the same treatment,
except that the freezing and grinding processes were
omitted.
Evaluation of total antioxidant capacity. An