叶黄素酯和叶黄素稳定性的研究
Stability of Lutein and Its Esters
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摘要: 研究光、热、酸、碱、金属离子、氧化剂和还原剂对叶黄素酯和叶黄素稳定性的影响.结果表明,光对叶黄素酯和叶黄素的稳定性影响很大,日光照射0.5h,二者的保存率仅为0.35%,而放置在暗处保存率基本不变;叶黄素酯和叶黄素对热较稳定,但随着温度的升高和加热时间的延长,保存率下降,降解速度加快;在相同的光、热条件下,叶黄素酯的稳定性优于叶黄素,叶黄素以与脂肪酸结合的形式存在,稳定性更强;强酸性条件对叶黄素酯和叶黄素有一定的破坏作用,而其在中性、碱性条件下较稳定;Fe3+、Fe2+、Cu2+对它们的破坏作用较强,保存率下降较多,而Zn2+、Mg2+、Ca2+、K+、Na+对它们基本无影响;氧化剂H2O2对其有轻微的破坏作用;还原剂Na2SO3对叶黄素酯和叶黄素影响不大,Vc可以使它们降解,与Vc共存叶黄素酯的降解程度比叶黄素大.Abstract: Stabilities of lutein and its esters against light, heat, acid, alkali, metal ions, oxidant and reductant were studied. Results showed that both lutein and lutein esters were unstable against light, and stable in darkness. Their preservation rate was 0.35% toward outdoor sunlight for 0.5 h while they were preserved constantly in darkness. They were slightly stable against heat but their degradation could be accelerated with decreased preservation rate under long time and high temperature. Lutein ester was more stable toward light and heat than lutein under the same condition and esterification of —OH group with fatty acids might stabilize lutein against heat and light. They were unstable with decreased preservation rate toward Fe3+,Fe2+, Cu2+ and strong acid while stable against Zn2+, Mg2+,Ca2+,K+,Na+, alkali and Na2SO3 as well as slightly stable toward H2O2. It was noted that VC could degrade significantly lutein esters and lutein, in which absorbance of lutein esters decreased more quickly than that of lutein.