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|標題:||Continuous Hot Pressurized Solvents Extraction of Scavenging DPPH (1,1-diphenyl-2-picryl-hydrazyl) Free Radical Compounds from Taiwan Yams-Dioscorea alata
|關鍵字:||Dioscorea;山藥;DPPH free radical;continuous hot pressurized solvent;DPPH 自由基;連續式熱壓溶劑||出版社:||化學工程學系||摘要:||
This study preliminarily investigates the scavenging-activity on the DPPH (1,1-diphenyl- 2-picryl-hydrazyl) free radical, individually by the extract of both meat and peel portions of three Taiwan yams “Dioscorea alata”. Liquid-liquid extractions were employed to generate six fractions, initially extracted by ethanol. Then, the aqueous solution of dried solid residues was sequentially fractionated by hexane, chloroform, ethyl acetate, and n-butanol. The EC50 value, defined as the UV absorption of DPPH concentrations sufficiently decrease down to 50% of the original value, was individually detected for six partitions. It was found that all peel portions have better effect on scavenging DPPH free radical than meat portions, especially for the ethyl acetate partition of the peel portion of Tai-nung #2 Yam. Its EC50 value (14.5µg/ml) was even lower than that of ascorbic acid (21.4µg/ml). There is no diosgenin found in three yams, however, there is 0.11 wt% in one yam imported from China. Furthermore, semi-continuous hot pressurized ethanol (HPE) was superior to hot pressurized water (HPW) in extracting the compound scavenging DPPH radical from purpurea Roxb peel. The recovery of four unknown compounds was corresponding to the scavenging ratio of DPPH free radical in the HPE extract. Finally, three-level and four-factor experimental design discovered that ethanol ratio and temperature were the most effective factors in order. Pressure and solvent-to-feed ratio were relatively not significant. 80% of aqueous ethanol, 20 (kg/kg) solid ratio, 180 psig, and 100℃ were found to be a suitable condition.
|Appears in Collections:||化學工程學系所|
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