紫甘薯色素理化性质及稳定性研究

Study on Stability and Physical and Chemical Properties of Pigment from Purple Sweet Potato

[目的]为紫甘薯色素的开发利用提供理论依据。[方法]以川山紫为材料,研究其色素的基本理化性质及pH值、温度、光照、氧化还原剂和金属离子对色素稳定性的影响。[结果]紫甘薯色素易溶于水、甲醇、乙醇等,不溶于丙酮、乙酸乙酯、乙醚和石油醚;紫甘薯色素水溶液在pH值为1.0-3.0时,性质稳定,呈鲜红色,随pH值升高色素颜色变浅,降解指数增大;温度为20-60℃时,色素性质稳定,温度超过60℃时,色素稳定性迅速下降;光照对色素稳定性影响较小,连续照射8 d后色素保存率为87%;色素的耐氧化性和耐抗坏血酸还原能力较差;Al^3＋和Zn^2＋具有护色效果,可提高色素的稳定性,而Fe^3＋对色素有破坏作用。[结论]紫甘薯色素为水溶性天然色素,主要成分为花色苷类物质。

[ Objective] The study was to provide the theoretical basis for development and utilization of pigment from purple sweet potato. [ Method ] With purple sweet potato variety Chuanshanzi as the material, the basic physieochemieal property of its pigment and the effects of pH value, temperature, light, oxidant and redactant and metal ions on the stability of pigment were studied. [ Result ] The pigment from purple sweet potato was easily soluble in water, methanol and ethanol, but insoluble in acetone, ethyl acetate, ether, and petroleum ether. When the pH value of aqueous solution of pigment from purple sweet potato was 1.0 - 3.0, the properties of the pigment was stable, bright red, and with the increase of pH value, the pigment eolour became shallower, and its degradation index increased. When the temperature was 20 -60 ℃, the properties of the pigment was stable, and when the temperature was over 60 ℃, the stability of the pigment was decreased rapidly. The effects of light on stability of pigment was little, after 8 d continuous irradiation, the preservation rate of pigment was 87%. The oxidative resistance and resistance of ascorbic acid reducing power was poor. Al^3＋ and Zn^2＋ had an effect of protecting the color of pigment, and could improve the stability of the pigment, but Fe^3＋ had a destructive effect. [ Conclusion ] The pigment from purple sweet potato was a kind of water-soluble natural pigment, and its main composition was anthocyanin substances.