應用濾紙色層分析法測定西番果中非氮有機酸之研完

Studies on the Determination of Non-Nitrogenous Organic Acids of Passion Fruit (Passiflora edulis) By Paper Chromatograph

濾紙色層分析法已廣被採用為果實中非氮有機酸之分離與檢定，但其鮮有利用於有機酸之定量之方法，本實驗即應用濾紙色層分析法聯合洗出法來分離並定量臺灣產之西番果（Passiflora edulis）中各種有機酸之含量。結果自該果汁中獲得5種有機酸，即枸櫞酸、蘋果酸、酒石酸、草酸和維生素丙。其中以枸櫞酸為最重要，約佔該果汁中全部有機酸65%，其他各種有機酸均較少。此等有機酸均依標準酸液所獲得之Rf值所檢出，然後依各種有機酸在濾紙上之位置，分別用洗出法與滴定法予以定量之。由本試驗研究所用之展開溶媒為：正丁醇、蟻酸、水、乙醚（4:1.5:1:0.5v/v）之混合液。此種展開溶媒不但展出各種有機酸之斑點十分清晰，同時可縮短 1/2之展開時間。依照本試驗所得之結果知，所有之非氮有機酸存在於西番果中，幾可全量分析出來。此可由已有混合之標準酸液回收結果予以證明，其中除了草酸、乙醇酸和維生素丙尚未安全收回，特別是維生素丙之收回量可能是在分析操作進行時部份受氧化作用所致。

Paper chromatography has been widely applied to isolate and identify some non-nitrogenous organic acids of fruit juice, but the quantitative determination of fruit organic acids are ra.rely adopted by this method. In this experiment, a combination of paper chromatography and eluted method was built to separate and titrate the individual organic acid content. and five kinds of organic acids were identified from Taiwan passion fruit. They are citric, malic, tartaric, oxalic and I-ascorbic acids. Amor:.g those acids, citric acid is the important organic acid preser:.t in it contained about 65 per cent to the total. Other acids are comparative low shown as Table 1. Those acids were identified by measurements of their respective Rf values by developing with a mixture of n-Butanol, formic acid, water and ether (4: 1. 5: 1: 0.5 v/v). And it is found that solvent system of this is vary_ satisfactory to develop the chromatogram for a short time by this studies. According to the results, the recovery of all the non-nitrogenous organic acid of standard solution was almost quantitative with exception of oxalic, glycolic and I-ascorbic acids, the results of which were obviously erratic. Especity, the cause upon the latter may be oxidized during proceeding. The passion fruit, Passiflora edulis, have originated in Brazil (2, 3) and have been cultivated in Taiwan since the 2nd Warld War time (1). For processing purpose, it is important to know what kinds and how much of its organic acids contained in fruit, and some of acids would perhaps effect on the reaction of the juice making due to the fact that passion fruit has widely been 1).This investigation was supported by the National Council on Science Development to which thanks are due. 2).Associate professor, Department of Horticulture, College of Agriculture, National Taiwan University dopted as juice material in recent years of Taiwan. The paper chromatography has been applied to the studies of the non-nitrog­enous organic acids present in plant tissues (4, 5), they ordinarily occure as complex mixture, from which isolation and identification have been pointed toward the possibility of chromatographic separations by several recent papers (7, 8). In 1952, Bulen (8) suggested that organic acids from plant tissues would be analysed by additional separations using both for chromatographic and chemical techniques. As the same time, Marshall (9) used a technique that described for computing these chromatographic positions and the migration of several organic acids in several solvent systems_ was analysed by the simple equation derived. Hsieh (6) showed that the partition chromatography on silica gel columns had successfully been applied to isolate and identify some non­nitrogenous organic acids present in sugar cane Juice. And Fink et al. (10) in 1963 had collected Rf value in various solvent systems on the paper chromato­gr1pl1Y. of several clases of compounds. On the quantitative estimation of the non-nitrogenous organic acids, though, there are many techniques to be enployed, those are as the spot area, the total color density, visual comparison and eluted methods (4, 5). The most satisfactory method for the quantitative analysis by the filter·paper chromatography may be selected. In this work, it was carried out to isolate and identify non-nitrog­enous organic acids in passion fruit by paper chromatography. From many preliminary tests the eluted method was found as the most suitable for this purpose during in combination of using of the titration method. The results show that the present method of investigation is not only applicable to provide a tool for the study of the organic acids of fruits, but also to present both of quality and quantity of the organic acids of passion fruit of Taiwan.