青稞紫色素的基本性质及其抗氧化能力

Basic Properties and Antioxidant Activity of Purple Pigment from Hulless barley

对西藏紫青稞种皮色素的基本理化性质、稳定性和抗氧化性进行了初步研究。结果表明:青稞色素为花色苷类色素,溶剂和pH值对其色调和色度有显著影响,在水、甲醇、乙醇溶液中,随pH变化,该色素可由红色逐渐转变为绿、棕黄或蓝紫色;该色素在较低的pH值条件下避光保存时更加稳定;金属离子K+、Na+、Ca2+、Mg2+、Zn2+及Al3+对该色素有较强增色、护色作用,其中高价态离子效果更明显,但不同离子对色素的结合方式或亲和性可能有差异;该色素具有较强的清除羟自由基(.OH)能力,清除率为50%时的色素浓度为9.7 mg/L,是一种较好的天然抗氧化剂。

In the present study, pigment isolated from Tibetan purple hulless barley was subjected to a primary study to characterize their basic physicochemical properties, stability and antioxidation. The results showed that the pigment was anthocyanin colorant which exhibited red, green, yellow-brown or bluish violet color depending on the solution and its pH value; the pigment was more stable at lower pH in the dark than at higher pH under light; metal ions including K ＋ , Na ＋ , Ca2 ＋ , Mg2 ＋ , Zn2＋ , Al3 ＋ , especially those highly charged ions had significant hyperchromic and protective effect on storage stability of the pigment;the binding modes or affinities between the metal ions and anthocyanin pigments could be different according to HPLC analysis; the great elimination elect on the hydroxy radical with IC50 values of 9.7 mg/L indicated hulless barley pigment was an excellent natural antioxidant.