The aim of this study was to investigate the antioxidant activity of thermal treatment yam (Dioscorea batatas DECNE.) in Korea. Thermal treatment yam was extracted by different solvents including 70% methanol, 70% ethanol and chloroform–methanol mixture (CM, 2:1, v/v). Then color property, total phenol content and antioxidant activity were analyzed. Yam possessed high L* value and H° value, which were 54.92±2.18 and 73.20±0.77, respectively. Thermal treatment yam exhibited great antioxidant activity evaluated by ABTS [2,2′ -azino-bis(3-ethylbenzothiazoline-6-sulfonic acid) diammonium salt] radical scavenging activity, DPPH (2,2-diphenyl-1-picrylhydrazyl) radical scavenging activity, reducing power, and ferric reducing antioxidant power. Total phenol contents of various extracts from thermal treatment yam increased in the following order: 70% methanol extract (63.53±0.33 mg CAE/g), 70% ethanol extract (69.47±1.00 mg CAE/g) and CM extract (97.49±0.66 mg CAE/g), respectively. The same trend was also could be found in antioxidant activity assays except for reducing power assay. These results implied that these extracts from thermal treatment yam might be useful to take a good part in prevention of human diseases and aging.

1. Introduction
 2. Materials and Methods
  2.1. Materials and chemicals
  2.2. Preparation of yam extracts
  2.3. Measurement of total phenolcontents (TPC)
  2.4. ABTS radical scavenging assay
  2.5. DPPH radical scavenging assay
  2.6. Reducing power assay
  2.7. Ferric reducing antioxidant power(FRAP) assay
  2.8. Color assessment
  2.9. Statistical analysis
 3. Results and discussion
  3.1. Yields
  3.2. Total phenol contents (TPC)
  3.3. ABTS radical scavenging activity
  3.4. DPPH radical scavenging activity
  3.5. Reducing power
  3.6. Ferric reducing antioxidant power(FRAP)
  3.7. Color property
 4. Conclusions
 References

• Han-Soo Kim(Department of Food Science and Technology, Pusan National University, Miryang 627-706, Korea)
• Yishan Duan(Department of Food Science and Technology, Pusan National University, Miryang 627-706, Korea)
• Jae-Young Ryu(Department of Urban Enviromental Engineering, Kyungnam University, Changwon 631-701, Korea)
• Sang-Woo Kim(East Sea Fisheries Research Institute, NFRDI, Gangneung, 210-861, Korea)
• Seong-Ho Jang(Department of Bioenviromental Energy, Pusan National University, Miryang 627-706, Korea) Corresponding author