Study on the extraction and stability of the yellow pigment from the petal of helianthus annuus L.

The extracting conditions and stability of the yellow pigment in Helianthus annuus L. petals had been studied. This pigment was soluble in acetone,methanol,ethanol and isopropanol. When extracting the pigment with ethanol,ethanol solution of the pigment had maximum absorptive peaks of ultraviolet-visible spectrogram at 225nm and 443nm. The yield rate of the pigment was 7.4%,the color value was E1%1cm(440nm)=284. After separated by HPLC,the pigment mainly contained four components. Under neutral and alkaline conditions,the pigment was yellow;under acid condition,the yellow paled. The pigment was stable under 60℃,but unstable under 80℃ for 2h. The pigment was stable under light condition. H2O2 and Na2SO3 increased the absorbance,while Vc had no effect on the pigment. Na2S2O3 decreased the absorbance. Salt,glucose and sucrose increased the absorbance while starch,citric acid,benzoic acid decreased the absorbance. Metallic ion like Fe3+ and Cu2+ changed the color of the pigment,but Na+,Mg2+,K+,Ba2+,Ca2+ and Al3+ had no effect on the pigment stability.