Consumption of fruits and vegetables has been conducted to be effective in the prevention of chronic diseases. In this study, 70% methanol, 70% ethanol and chloroform-methanol mixture (CM, 2:1, v/v) were used as solvents in the extraction of apple peels. The total phenol content, total flavonoid content and antioxidant activity of various extracts were investigated using in vitro assays. The extract obtained by 70% methanol showed the highest total phenol content (20.87±0.17 mg CAE/g), ABTS [2,2′-azino-bis(3-ethylbenzothiazoline-6-sulfonic acid) diammonium salt] radical scavenging activity and ferric reducing antioxidant power. However, 70% ethanol extract possessed the strongest antioxidant activity assayed by DPPH (2,2-diphenyl-1-picrylhydrazyl) radical scavenging activity and β-carotene bleaching method. And CM extract was found to show the highest total flavonoid content with the value of 9.26±0.06 mg QE/g. These results indicated that apple peels can be used in dietary applications with a potential to reduce oxidative stress.

1. Introduction
 2. Materials and Methods
  2.1. Materials
  2.2. Preparation of apple peel extracts
  2.3. Measurement of total phenolcontents (TPC)
  2.4. Measurement of total flavonoidscontent (TFC)
  2.5. 2,2-Diphenyl-1-picrylhydrazyl (DPPH)radical scavenging activity assay
  2.6. 2,2′-Azino-bis(3-ethylbenzothiazoline-6-sulfonic acid) diammonium salt(ABTS) radical scavenging activityassay
  2.7. β-carotene bleaching assayThe antioxidant activity of different extract
  2.8. Ferric reducing antioxidant power(FRAP) assay
  2.9. Statistical analysis
 3. Results and Discussion
  3.1. Yields
  3.2. Total phenol contents (TPC)
  3.3. Total flavonoid contents (TFC)
  3.4. DPPH radical scavenging activity
  3.5. ABTS radical scavenging activity
  3.6. β-carotene bleaching assay
  3.7. Ferric reducing antioxidant power(FRAP)
 4. Conclusions
 Acknowledgement
 References

• Gyeong-Hwuii Kim(Department of Biological Science and Technology, Yonsei University, Seoul 03722, Korea)
• Yishan Duan(Department of Food Science and Technology, Pusan National University, Miryang 50463, Korea)
• Soon-Hee Gwon(College of Nano Science and Technology, Office of Administration, Pusan National University)
• Han-Soo Kim(Department of Food Science and Technology, Pusan National University, Miryang 50463, Korea) Corresponding Author