台灣常用蔬菜的抗氧化力指標FRAP與總酚類含量

Abstract

蔬果提供人體抗氧化的保健作用，多攝取可減少疾病的發生。為了建立台灣蔬菜的保健資訊，本試驗以三價鐵離子還原抗氧化力分析法（FRAP assay）縱觀分析台灣各種蔬菜的總抗氧化力，並利用福林酚試劑（Folin-Ciocalteu reagent）分析法量測其總酚類含量。所有受測蔬菜的平均抗氧化力介於0.4~35.7μmol FeSO4/g f.w.，總酚類含量介於0.7~47.7μmol GAE/g f.w. 高總抗氧化力（＞10μmol FeSO4/g f.w.）的蔬菜有短錐形紅辣椒、薑、甜椒、紫色甘藍、黑皮長豇豆、甘藷葉、羅勒（九層塔）、蓮藕、豌豆嫩梢及過溝菜蕨（過貓），這些蔬菜同時也具高總酚類含量（＞10μmol GAE/g f.w.）。蔬菜以供食用部位分類，茄果類平均抗氧化力9.6μmol FeSO4/g f.w.為最高，瓜果類1.6μmol FeSO4/g f.w.最低；總酚類含量方面則皆無顯著差異。濃綠色以及顏色鮮艷的蔬菜，抗氧化力與總酚類含量皆較高於白色或淡色的蔬菜。將受試蔬菜依中醫熱、溫、涼及寒四氣性質分類，結果指出各類蔬菜平均抗氧化力與總酚類含量皆呈現由高到低的順序。本試驗受測78種蔬菜的單位鮮重的抗氧化力與總酚類含量有正相關（R2=0.46，p<0.001）；其中，豆科、瓜果類及茄科等蔬菜抗氧化力與總酚類含量有更高度的相關性，決定係數（R2）分別為0.91、0.88及0.80，而十字花科與菊科蔬菜的決定係數則不高（R2分別為0.23及0.28），結果顯示不同類別的蔬菜，總酚類對總抗氧化力的貢獻度不同，抗氧化成分有所差異。在不同部位與不同前處理的蔬菜抗氧化力方面，小松菜與本地芹菜葉片之葉身部位抗氧化力是高於葉柄部位；蓮藕地下莖之節位部份的單位乾重抗氧化力是節間部位的3.5倍；大蒜經切碎後放置20分鐘再進行均質分析，其抗氧化力可提高50%；而含有外皮的絲瓜單位乾重抗氧化力是高於去皮的絲瓜。預期外地，包心白菜單位乾重抗氧化力，有由內層葉片到外層葉片遞減的趨勢。由國人蔬菜攝取的情況，可估計出台灣成人平均每天從蔬菜類食物中所獲得的抗氧化力為1442μmol FeSO4，所獲得的總酚類為1524μmol GAE，其中深色蔬菜類所提供的抗氧化力與總酚類皆約佔全部的75%。

Fruit and vegetables play an important role in antioxidant protective effect for human against the risk of several diseases. To establish information of health-promoting properties of Taiwan vegetables, the total antioxidant activity（TAA）and total phenolic content（TP）of Taiwan vegetables were investigated by Ferric reducing antioxidant power（FRAP）assay and Folin-Ciocalteau assay. The TAA and TP varied from 0.4 to 35.7μmol FeSO4/g f.w. and from 0.7 to 47.7μmol GAE/g f.w., respectively. The vegetables with higher TAA (>10μmol FeSO4/g f.w.) and TP (>10μmol GAE/g f.w.) are short chili pepper, ginger, colored sweet pepper, red cabbage, black yard-long bean, sweet potato vine, basil, Indian lotus root, early dwarf pea, and common bracken. The TAA was the highest in fruits of Solanaceae and the lowest in fruits of Cucurbitaceae. The TAA and TP were significantly higher in colorful vegetables than in light color vegetables. As classified the tested vegetables according to hot, warm, cool, and cold properties of Chinese medicine, the average TAA and TP of each category were in the decrement order. A positive linear relationship (R2 =0.46, p＜0.001) obtained between TAA and TP in 78 kinds vegetables. The coefficient of determination between TAA and TP was higher in Leguminous, Cucurbitaceous and Solanaceous vegetables (r2=0.91, 0.88, 0.80, respectively), and lower in Brassicaceous and Asteraceous vegetables (r2=0.23 and 0.28, respectively). These results suggested that the contribution of TP to TAA varies among varieties of vegetable, and antioxidants as well. The TAA of Komatsuna and Chinese celery were higher in the leaf blade than in the leaf stalk, and the TAA of Indian lotus root was 3.5 fold higher in nodes than in internodes. The TAA of garlic in creased 50% as left at room temperature for 20 minutes after minced before extraction. The TAA of vegetable sponge was higher in fruit with skin than in ones without skin. Unexpectedly, Chinese cabbage has the decrement in TAA from inner to outer leaves. The average TAA and TP consumed from vegetables are 1442μmol FeSO4 and 1524μmol GAE per adult in Taiwan daily. The percentage of TAA and TP consumed from deep-colored vegetables is about 75% in all vegetables.