新鮮與乾燥菱角仁（Trapa taiwanensis Nakai）萃取物之抗氧化力與酚類化合物之探討   全文下載

Antioxidant Activity of Phenolic Compounds Extracted from Fresh and Dried Water Caltrop Pulp (Trapa taiwanensis Nakai)

本研究以菱角為材料探討乾燥處理對其抗氧化力與酚類物質含量之影響。此實驗利用甲醇萃取新鮮、冷凍乾燥與熱風乾燥處理樣品，結果發現在濃度10 mg/mL 時，DPPH 捕捉力分別為87.2、61.4 和52.1%；樣品濃度5 mg/mL 時，還原力為0.75、0.41 和0.29；在40 mg/mL，銅離子螯合力為29.6、14.8 和34.3%。且新鮮樣品的K 值、總酚含量與類黃酮含量較高於冷凍乾燥處理和熱風乾燥處理，但新鮮樣品的IC50 較低於冷凍乾燥處理和熱風乾燥處理。而HPLC 對菱角仁之酚類物質組成分析，顯示其含有四種酚類化合物（阿魏酸、沒食子酸、槲皮酮和羥基肉桂酸）。故經結果得知新鮮樣品甲醇萃取物具有較乾燥樣品高的抗氧化力，且經處理後冷凍乾燥較熱風乾燥的抗氧化力與酚類物質含量較高。

Water caltrop (Trapa taiwanensis Nakai) was used as the raw material to investigate the effects of drying treatments on the antioxidant activities and phenolic compounds of water caltrop. For methanolic extracts from fresh, freeze dried, and hot air dried samples, at 10 mg/mL, the scavenging ability on 1,1-diphenyl-2-picrylhydrazyl (DPPH) radicals was 87.2%, 61.4% and 52.1%, respectively. At 10 mg/mL, the reducing power was 1.63, 0.81 and 0.52, respectively. At 40 mg/mL, the chelating ability on copper ions was 29.6%, 14.8% and 34.3%, respectively. The IC50, half inhibition concentration is the concentration, at which the radicals or ions was scavenged or chelated by 50%. The total phenolics and flavonoids contents were higher in the fresh samples, while the IC50 values were lower. The HPLC analysis showed that four phenolic compounds (gallic acid, quercetin, ferulic acid, and hydroxycinnamic acid were found in water caltrop), and that only had three phenolic compounds (gallic acid, quercetin, and ferulic acid were found after drying). While the freeze-drying treatment could preserve more antioxidant activity of the water caltrop pulps than hotair drying treatment, different drying water caltrop pulps exhibited different antioxidant mechanisms.