红曲红色素稳定性研究及光热降解动力学分析

Study on Stability and Photic and Thermal Degradation Kinetics of Monascus Red Pigment

红曲红色素是一种在食品行业应用广泛的天然色素。本文研究了pH、光照和温度对红曲红色素稳定性的影响,并建立光热降解动力学方程。结果表明,当溶液的pH<5或pH>9时,红色素稳定性降低,且pH升高至13时其溶液颜色由红色变为黄。红曲红色素的光稳定性较差,随着光照时间的增加,色素保存率不断下降,经过6h的照射后,色素保存率降至77.4%。通过对数据进行零级、一级和二级线性动力学方程的拟合,发现红曲红色素光降解更符合二级动力学。温度对红曲红色素稳定性影响较大,随着温度的升高,红曲红热降解速率不断加快,热降解符合一级动力学方程,降解反应活化能Ea仅为43.5k J·mol^(-1)。

Monascus red pigment is a natural pigment which is widely used in food industry. In this study, effect of PH, light, and temperature on the stability of monasus red pigment and light and thermal degradation characteristics were studied. The results indicated that when pH5 or pH9, the stability of monasus red pigment decreases.Furthermore, while the PH value increases to 13, the solution color changes from red to yellow. Monascus red pigment shows poor photostability, for the illumination time going on, the preservation rate of monasus red pigment decreases to 77.4% 6 hours later. Light degradation dynamic model of monasus red pigment was established. It was proved that it was in accordance with the second order reaction kinetics. The stability of monasus red pigment is significantly influenced by temperature, for the higher the temperature is, the faster the degradation rate. The thermal degradation dynamic model of monasus red pigment was in accordance with the first order reaction kinetics and the thermal degradation activation energy（Ea） of Monascus red pigment was 43.5 kJ·mol^-1.