红曲色素不同成分的光稳定性研究

PHOTOSTABILITY EVALUATION OF THE DIFFERENT COMPONENTS OF MONASCUS PIGMENT

对红曲红色素Rubropunctamine和Monascorubramine在日光照射下的稳定性进行了研究。结果表明,红曲色素光降解符合一级动力学反应,并且不受溶解氧的影响。色素光降解的半衰期与色素浓度呈正相关性。使用二极管阵列检测器的高效液相色谱仪对两种色素纯品的光降解过程进行表征发现,Rubropunctamine和Monascorubramine对光敏感,光照后降解形成新的无色物质。色差仪评价显示,随着褪色的进行,色素溶液的色饱和度逐渐减小,色相角保持不变。

The photostabilities of Rubropunctamine and Monascorubramine were determined under sunlight. Photobleaching tests showed that the degradation of pigment accorded with first-order kinetic reaction and the bleaching kinetics have no obvious difference in the presence or absence of oxygen. Their half-lives increased with increasing initial pigment concentration. The degradation patterns of those pure pigments over time were analyzed by HPLC with photodiode array detector （PDA） method. Rubropunctamine and monascorubramine were sensitive to light, a colorless compound was found after the light illumination due to decomposition reaction. L^＊, a^＊ and b^＊ values of the CIELAB color system for the two pigments were measured. Values of chroma decreased and the hue is not changed during the test.