title: Extraction characteristics of subcritical water depending on the number of hydroxyl group in flavonols.
abstract: This study compared the efficiencies of using subcritical water, hot water, and organic solvents to extract flavonols from black tea, celery, and ginseng leaf. The effect of key operating conditions was determined by varying the temperature (110-200°C), extraction time (5-15min), and pressure (about 10MPa) and the extracts were analysed quantitatively using HPLC. The yields of myricetin, quercetin, and kaempferol from plants were maximal at extraction temperatures of 170°C, 170°C and 200°C, respectively, and they depend on the number of hydroxyl groups included in the chemical structure of the flavonols, with more of those with fewer hydroxyl (OH) groups attached being extracted at higher temperatures. The results also showed that the yields of flavonols by subcritical water extraction were 2.0- to 22.7- and 1.8- to 23.6-fold higher than those obtained using the ethanol and methanol as traditional extraction methods, respectively.
authors.affiliation: Department of Food and Food Service Industry, Kyungpook National University, Sangju 742-711, South Korea.
authors.forename: Chan-Ick
authors.initials: CI
authors.lastname: Cheigh
authors.affiliation: Department of Food Science and Engineering, Ewha Womans University, Seoul 120-750, South Korea.
authors.forename: Seo-Yeon
authors.initials: SY
authors.lastname: Yoo
authors.affiliation: Department of Food Science and Engineering, Ewha Womans University, Seoul 120-750, South Korea.
authors.forename: Min-Jung
authors.initials: MJ
authors.lastname: Ko
authors.affiliation: Department of Agricultural Biotechnology and Center for Food and Bioconvergence, Seoul National University, Seoul 151-742, South Korea. Electronic address: pschang@snu.ac.kr.
authors.forename: Pahn-Shick
authors.initials: PS
authors.lastname: Chang
authors.affiliation: Department of Food Science and Engineering, Ewha Womans University, Seoul 120-750, South Korea. Electronic address: mschung@ewha.ac.kr.
authors.forename: Myong-Soo
authors.initials: MS
authors.lastname: Chung
mesh_terms: D000077102:Apium / Q000737:chemistry*; D028241:Camellia sinensis / Q000737:chemistry*; D005591:Chemical Fractionation; D002851:Chromatography, High Pressure Liquid / Q000379:methods; D044948:Flavonols / Q000032:analysis / Q000737:chemistry*; D015394:Molecular Structure; D005894:Panax / Q000737:chemistry*; D010936:Plant Extracts / Q000737:chemistry* / Q000302:isolation & purification*; D011794:Quercetin / Q000032:analysis; D014867:Water / Q000737:chemistry
chemical_list: D044948:Flavonols; D010936:Plant Extracts; D014867:Water; D011794:Quercetin
keywords: Hydroxyl group; Kaempferol; Myricetin; Quercetin; Subcritical water extraction