Effects of Microwave Energy on the Tocopherols of Soybean Seeds

The effects of microwave heating on the tocopherols of soybeans were studied in relation to chemical changes in the lipids. The amounts of α‐, β‐, γ‐, and δ‐tocopherols in the soybeans before microwave treatment ranged from 6.2 to 13.0, 2.7 to 4.5, 60.0 to 76.8, and 45.7 to 57.9 mg/100 g lipid, respectively, γ ‐ and δ‐Tocopherol concentrations gradually decreased, and as much as 40% of the tocopherols originally present in the soybeans was lost after 12 min heating. However, microwave treatment of soybeans for 6 min, which would be optimal to prepare full‐fat soyflour without a burnt odor, retained ca. 90% of the individual tocopherols with a few exceptions and caused no significant difference in the chemical changes of the lipids.