Stability and Sensory Evaluation of Naphthoquinone Pigments from the Roots of Lithospermum erythrorhizon

자근(紫根)으로부터 분리한 Naphthoquinone류 색소의 pH 안정성 및 관능검사

  • Published : 1994.04.01

Abstract

The purplish red pigment from the roots of Lithospermum erythrorhizon, a Korean edible wild plant, has been investigated concerning it's value as a natural colorant for Korean traditional foods. An attempt was made to isolate pigments and define their characteristics. Two compounds of isobutylshikonin and acetylshikonin were identified by melting point determination and spectra of UV, IR, and $^{1}H-NMR$. To examine the utility of these naphthoquinone pigments for foods, the effect of various pH values on stability were determined over a period of storage. Buffered solutions of acetylshikonin and isobutylshikonin at pH 3 and 5 showed stable purplish red. The absorption maxima if acetylshikonin and isobutylshikonin over the range of pH 3 to 7 were 518 nm and 520 nm, respectively. A bathochromic shift to 588 nm at pH 10 was observed on these two naphthoquinone pigments. Sensory evaluation was performed with acetylshikonin and isobutylshikonin of identical absorbance. These two pigments revealed purplish red color in Munsell system.

Keywords

naphthoquinone;acetylshikonin;isobutylshikonin;stability;sensory evaluation