Extraction, Purification And Characterization Of Pigment In Flowers Of Hibiscus Rosa-sinensis L.

The safe and nontoxic anthocyanin extracted fro m flowers and fruits of various kinds of plants possess the beneficial nutrition and pharmacologic function to human being.It has been widely used in many industries such as foods,medicine and cosmetics.People pays more and more attention to natural pigment.In this project, extraction,purification and characterization of pigment in flowers of Hibiscus rosa-sinensis L.was systemic studied.The result showed that the optimum extraction method by ultrasonic as follows: extractant was 0.1%HC1-95 ethanol(70:30 V/V),ratio of solid to liquid was 1:150, extraction time was 30 min,and extraction temperature was 60℃,the maximum absorption wavelength of the pigment was 525 nm,and the extraction rate was 24.28%.The color scale of crude extract in flowers of Hibiscus rosa-sinensis L.was 7.01.In order to improve the purity of anthocyanin,we used ethanol precipitation,the gradient polar solvent extraction and purification of macroporous resin by turns.First, the protein and polysaccharides impurity in the pigment were removed by ethanol precipitation;second,the lipids,chlorophyll and polyphenols were removed by he gradient polar solvent extraction;then,the pigment was further purified by macroporous resin.AB-8 macroporous resin was suitable for purification of pigment extracted in flowers of Hibiscus rosa-sinensis L.Static adsorption dynamics experiment showed that the absorption equilibrium could be achieved in 8h,and elution result is the best by 90%ehanol,and elution rate is 75.18%.The absorption and desorption experiment of AB—8 macroporous resin showed that the pigment solution(pH2.0) was suitable to use as loading solution and loading flow rate was 1 mL/min when absorbed;the 90%ethanol(pH2.0) was properly used as elution buffer when desorbed.The elution flow rate is 1mL/min and the elution rate is 86.90%.The color scale of purified extract in flowers of Hibiscus rosa-sinensis L.was 16.74, 1.39 times as much as that of crude extract.We could preliminally deduce that the key component of pigment in flowers of Hibiscus rosa-sinensis L.is anthocyanin by the colors in pigment solution with different pH and the spectrogram of ultra violet-visible light and infrared spectrum. The pigment in flowers of Hibiscus rosa-sinensis L.is water soluble and the stability of the pigment was affected greatly by the alteration of pH,the pigement is sensitive to incident light and possess good heat stability,the color of the pigment was not mainly affected by the frequently used food additives,Vc possess es hyperchromic effect to the pigment,strong oxidant H₂O₂ accelerated the degradation of the pigment, different kinds of metals affected differently on the stability of the pigment,Ca²⁺ and Al³⁺ has no influence on its stability,Zn²⁺ increased the absorbance of the pigment, resulted in the dark color,Fe³⁺ and Cu²⁺ degraded the pigment,resulted in the light color.In vitro study demonstrated that the pigment in flowers of Hibiscus rosa-sinensis L.possessed good antioxidation.It can be used as hydrogen donator to remove 1,1-diphenyl 2-picrylhydrazyl(·DPPH),but the capability is lower than that of Vc and BHT.It had a strong scavenging activity on superoxide radical(O₂^-) and hydroxyl radical (·OH).Moreover,the restraint result of it on peroxidation from polyunsaturated fatty acid(PUFA) was effective.Also,it can be used as electron donator,reducted Fe³⁺ to Fe²⁺.