Abstract:Properties and stability of the pigment from water caltrop outer peel was investigated in this study. Results indicated that this pigment was easily soluble in water, sodium hydroxide and ethanol but insoluble in benzene, ether, and petroleum ether. An obvious effect of pH on stability of this pigment was observed and this pigment exhibited better stability in alkaline environments. In addition, Cu2+ revealed a color enhancement effect on this pigment, while K+, Na+, Ca2+, exhibited little effect. In contrast, Fe2+, Al3+ and Zn2+ contributed obvious adverse effects. It was found that the pigment was poor resistant to light and oxide, but the effects of heat on stability of pigment were little.
