黑米色素在超声场中稳定性研究

Study on stability of the pigments from black rice under ultrasonic condition

研究黑米色素在超声场中稳定特性,探讨了初始浓度、p H、超声频率、超声功率和反应温度等因素对黑米色素稳定性的影响,同时判断反应级数,计算活化能及指前因子并与非超声环境相比较。发现在超声条件下,黑米色素在偏酸性环境下随着溶液p H降低,稳定性增加。黑米色素溶液浓度对稳定性影响较小。但黑米稳定性随反应温度,超声频率以及超声功率的升高而下降。在相同超声频率下,超声功率越高,黑米色度稳定性越差。经过反应动力学分析,黑米色素在超声及非超声环境下,化学反应都符合一级反应规律。在超声场中,活化能为37697.94k J/mol,指前因子为3800.55s-1。在非超声环境下,活化能为39531.41k J/mol,指前因子为2887.07s-1。比较可知,超声可以降低活化能,增加有效分子碰撞次数,使降解反应更容易发生。

The stability of black rice pigments in the ultrasonic field was studied. The paper discussed the black rice pigments＇ stability under different influence factors such as ：p H,initial concentration,ultrasonic frequency,ultrasonic power and reaction temperature. The the reaction order was determined and activation energy and per exponential factor were calculated. The results found that in ultrasound field,the black rice pigments is more stable with the decrease of p H. The solubility has little effect on the stability. With the increase of temperature,ultrasonic frequency and ultrasonic power,the stability went down. Under the same ultrasonic frequency,the higher ultrasonic power,the worse pigments＇ stability. The reactions of black rice pigments both in ultrasonic field and non ultrasonic field obey the first-order reaction. In ultrasonic field the activation energy was 37697.94 k J/mol and the pre exponential factor was 3800.55s^-1. In non ultrasonic environment,the activation energy was 39531.41 k J/mol and the pre exponential factor was 2887.07s^-1. Ultrasound can reduce the activation energy,increase the effective molecular collision probability which makes the degradation reaction occur more easily.