水溶性天然色素系統分析法之探討

INVESTIGATION ON SYSTEMATIC ANALYSIS OF WATER-SOLUBLE NATURAL DYES

探討濾紙層析法（Paper Chromatography），薄層層析法（Thinlayer Chromatography）及分光光度法用於分離鑑別九種水溶性天然色素之最佳條件。結果濾紙層析法的展開溶媒以 n-Butanol：Acetic acid：Water （4：1：5，取上層液）最佳，另外 n-Butanol：Acetic acid：Water （4：1：2） 及 Isoamyl Alcohol：Acetone：Water （5：6：5） 可幫助鑑別。以聚醯胺（Polyamide）為擔體之薄層層析法的展開溶媒以 Isopropanol：Formic acid：Water （7：1：3） 最佳。由食品中分離色素，以 SEP-PAK C18 Cartridge 取代傳統之聚醯胺管柱（Polyamide Column），其方法迅速簡便，檢體所需量少且干擾少，核黃素（Riboflavin）不被聚醯胺吸附，但可被 SEP-PAK C18 Cartridge 吸附。配合濾紙層析法或薄層層析法，可將九種水溶性天然色素分離鑑別，效果良好。自台北市區抽購標示含天然色素之檢體三十件，調查結果：水溶性婀娜多二件，核黃素一件，銅葉綠素納二件，糖焦色素二件，藏花素二件。顯示本法應用於食品中天然色素之分離鑑別，結果良好。

A method is described for the rapid detection of 9 water-soluble natural dyes in foods. Sample solution, prepared by aqueous extraction of foods, was shaken with ether to remove oil-soluble materials. The solution was adjusted to pH 3-4. The dyes in the solution were then adsorbed by SEPPAK C18 cartridge and eluted with 0.05% HCl in methanol. The dyes were identified by paper chromatography, thin-layer, chromatography and visible spectrophotometry. The solvent systems used for the chromatographies were as follows : paper chromatography, n-butanol : acetic acid : water (4 : 1 : 5, upper layer); polyamide thin-layer chromatography, isopropanol : formic acid : water (7 : 1 : 3). This method was applied for the detection of water-soluble natural dyes in 30 samples, including candies, soft drinks and other foods. The results showed that the water-soluble dyes in the samples were: annatto (water-soluble) 2, riboflavin 1, sodium copper chlorophyllin 2, caramel 2, and crocin 2.