Determination of quercetins in onion extracted with pressurized liquid
2005
Oki, T.(National Agricultural Research Center for Kyushu Okinawa Region, Nishigoshi, Kumamoto (Japan)) | Abe, H. | Masuda, M. | Nakagawa, T. | Suda, I.
Pressurized liquid extraction (PLE) was applied to extract quercetin-3, 4'-diglucoside (Q-3, 4'-diGlc) and quercetin-4'-glucoside (Q-4'-Glc) in onion for labor saving of extraction process. The experimental extraction parameters such as solvent composition, temperature, static time, and static cycle have been investigated. As a result, the optimum conditions were selected as follows: solvent composition ; 80% ethanol solution, temperature; 40 deg C, static time; 5 min, and static cycle; 4. Once the optimum conditions were established, the extracts were prepared from 13 onion cultivars harvested in Saga, Nagasaki, Hyogo and Hokkaido prefecture. The content of quercetins in the extract was determined by HPLC. The total contents of Q-3, 4'-diGlc and Q-4'-Glc varied according to the cultivar, ranging from 31.7 to 108.3mumol/100 g-FW. The 1, 1-diphenyl-2-picrylhydrazyl (DPPH) radical-scavenging activity increased with the increase of the total contents of Q-3, 4'-diGlc and Q-4'-Glc, and the correlation coefficient between then was 0.803. The tendency was observed that the content of Q-3, 4'-diGlc was larger than that of Q-4'-Glc in onion harvested in Kyushu region, and vice versa in Hokkaido region.
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