Subcritical Water Extraction of Nutraceutical Compounds from Citrus Pomaces

Abstract

Subcritical water (SCW) extraction of citrus pomaces (CPs) was carried out, and antioxidant activity and nutraceutical compound levels of the SCW extracts were evaluated in detail. At first, CP samples were subjected to the SCW extraction under various conditions focusing on the extraction temperature and time. Consequently, the highest total phenol contents, radical scavenging activity, and reducing power were found when extraction was carried at 200°C and 1.4 MPa for 60 min. Furthermore, the amounts of three kinds of polymethoxylated flavones (sinensetin, nobiletin, and tangeretin) in the SCW extracts also showed the highest values under this condition. These results indicate that SCW is an effective medium for the fast and highly efficient extraction of the antioxidants and nutraceutical compounds from CPs.

Keywords:

• Antioxidant activity
• citrus pomaces
• polymethoxylated flavones
• subcritical water extraction

ACKNOWLEDGEMENTS

This study was supported by the Ministry of Science and Technology (MOST) and the Korea Science and Engineering Foundation (KOSEF) through the Coastal Resource and Environmental Research Center (CRERC) at Kyungnam University (R12-1999-025-10001-0). This study was also supported by Chubu University Grant (A), Grant-in-Aid for Scientific Research (C) (19550085) of Japan Society for the Promotion of Science, and the Research Grant for Asia Science and Technology Cooperation Promotion Strategy: (2) Solution of Research Issues Shared by Asian Regions (Studies on Extracting Resources from Bio-Wastes by the Refinery Technology) from the Ministry of Education, Culture, Sports, Science and Technology (MEXT) of Japan (2006–2008). Jong-Wan Kim was financially supported by Brain Korea 21 Program.

Notes

^a–e Different letters within a row are significantly different (p < 0.05), n = 3.

^w–z Different letters within each extract are significantly different (p < 0.05), n = 3.

^a–e Different letters within a row are significantly different (p < 0.05), n = 3.

^w–z Different letters within each extract are significantly different (p < 0.05), n = 3.

DPPH radical scavenging activity of vitamin C (a positive control) at concentration of 100 µg/ml was 85.1%.

^a–e Different letters within a row are significantly different (p < 0.05), n = 3.

^w–z Different letters within each extract are significantly different (p < 0.05), n = 3.

Reducing power of vitamin C (a positive control) at concentration of 100 µg/ml was 0.911 OD.

^a–e Different letters within a row are significantly different (p < 0.05), n = 3.

^x–z Different letters within each extract are significantly different (p < 0.05), n = 3.