Stability and Degradation Kinetics of Anthocyanins from Dendrobium officinale

In onder to effectively control the stability of anthocyanins in the actual production process of D. officinale products,the effects of pH,temperature,light,H₂O₂,Na₂SO₃,glucose,sucrose,and preservatives agent were determined. Results showed that the anthocyanins were sensitive to pH,and the stability of D. officinale anthocyanins under acidic conditions was stronger. The thermal degradation of anthocyanins followed a first-order kinetic equation,with the increasing of temperature,the degradation rate(k)were increasing,and the half-life(t_1/2)were declining. At pH8.0,the activation energy(E_a)was the lowest(37.17 kJ/mol),while the highest value(71.66 kJ/mol)was observed at pH2.0.The thermal degradation reaction was a non-spontaneous endothermic process. Both light and H₂O₂ accelerated the degradation of anthocyanins,and the degradation rate increased with the increasing of H₂O₂ concentration. The degradation of anthocyanins was inhibited by 0.20% Na₂SO₃,but promoted by 0.10% and 0.15% Na₂SO₃. In addition,glucose,sucrose and potassium sorbate,sodium benzoate accelerated the degradation of anthocyanins. In the actual production and storage process of D. officinale products,the excipients with less destructive effect on anthocyanins should be selected and stored under low temperature and avoid light.