| 摘要： Merck Nitrate Test以比色法為基礎，偵測界限在5 ~ 225 mg / kg f.w.之間，超過最高濃度限制的測試液須再稀釋才能分析。以Merck test測量蔬果內的硝酸離子含量，並與HPLC相互對照比較，含較低 硝酸離子濃度且顏色鮮豔的作物經Merck test得到的數值較HPLC 高，誤差大；反之，高硝酸離子含量的綠色作物之Merck test結果較 低且差距小。不過，無論濃度是高或低，Merck test與HPLC的R2 值高達0.99，顯見Merck test的可靠性相當高。 調查臺北市傳統市場販賣的新鮮蔬菜、水果內的硝酸離子(NO3-) 和維他命C(Vitamin C)含量。在硝酸離子方面，每100公克鮮重的新 鮮葉菜類含有量最高為100 ~ 330 mg，之後依序為花菜類和根菜類 (30 ~ 40 mg)，果菜類(1 ~ 20 mg)，水果類最低，幾乎無法測出(1 ~ 2 mg)。在維他命C方面，番石榴含有最高的濃度(204.30 mg)，其後為 葉菜類(75 ~ 155 mg)，水果類(20 ~ 80 mg)，花菜類(55 mg)，果菜類 (20 ~ 40 mg)及根菜類(15 ~ 30 mg)。 硝酸離子和維他命C在蔬果體內的分佈並不平均，硝酸離子主 要聚積在根部的頂端，莖部的基端，外葉與葉柄-莖部位及果實的果 梗端和果皮部位。維他命C則是在根、莖的頂端，內葉和葉身部位 及果實的果皮部位，至於果肉內的分佈無規律可循。 探討菠菜和甘薯葉在室溫貯藏與冰箱冷藏期間硝酸離子和維他 命C含量的變化情形。不同作物種類與不同時期的試驗結果並不一 致，但外觀品質在貯藏後期明顯敗壞。Analyses on nitrate and ascorbic acid in vegetables and fruits havebeen conducted. The high R2 value(0.99)depicted a close correlationbetween HPLC and Merck nitrate test methods. 31 vegetables and fruits collected from tra ditional markets in Taipeihave been analyzed. Fresh leafy vegetables contained the highest nitrate(100-300 mg / 100 g f.w.),whereas the flower and root vege tables contained30-40 mg, fruit vegetables contained 1-20 mg. Fruits containe d the leastamount(1-2 mg). Guava contained the highest ascorbic acid(204.30 mg /100 g f.w.) among the analyzed crops, which were followed by leafy vegetable s( 75-115 mg), fruits(20-80 mg), flower vegetables(15-30 mg), fruit vegetables (20-40 ,g) and root vegetables(15-30 mg). In general, NO3- accumulates in t he root apex, stem end, outer leaves,leaf stalk, fruit apex and pericarp. Asco rbic acid accumulates in the rootand stem apex, inner leaves, leaf blade and p ericarp. It varies irregularlyin the fruit. Studies on the changes of nitra te and ascorbic acid contents of spinach and sweet potato leaves both under room temperature and cold storage conditions resulted inconsistently. |
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