Figure 6: Stabilities at 60°C of naked (□) and encapsulated (■) α-lipoic acid powders. The nano-capsule powder was prepared by freeze-drying its solution of which the composition was 1% α-lipoic acid and 5% polyoxyethylene (20) stearyl ether, XMg=0.5, and XCO=0.2. Each sample was heated at 60°C for 2 hours. The remaining amount of 1 α-lipoic acid was determined by HPLC.