Stability and Degradation Kinetics of Anthocyanins from Red Cabbage

In order to effectively control the degradation of anthocyanins during deep processing of red cabbage,the effects of pH,temperature,light,metal ions and external additives on the stability of anthocyanins were studied. Experiments showed that the stability of red cabbage anthocyanins could be greatly affected by pH,temperature and light. The 5 h retention rate of anthocyanins at pH2.0 was 92.92%±0.69%,and the 5 h retention rate of anthocyanins at a temperature of 40 ℃ in the dark was 70.50%±0.52%,which showed a strong stability of anthocyanin.The stability of anthocyanins could be improved by adding different concentrations of metal ions including K⁺,Mg²⁺ and Na⁺,low concentrations of Fe³⁺(0.01~0.02 g/mL)and ascorbic acid(0.03 g/mL),saccharose and lactose. The oxidizing agent of H₂O₂,the reducing agent of Na₂SO₃,high concentrations of Fe³⁺(0.03~0.04 g/mL),and ascorbic acid(0.09 and 0.12 g/mL)would accelerate the degradation of anthocyanins while the degradation rate would rise as the concentration increased. The thermal degradation reaction of anthocyanins was in accordance the first-order kinetics,the rate of degradation would rise as the temperature rose and the half-time period was reduced. The maximum of t_1/2 was 67.28 h at 50 ℃ pH2.0,and the maximum activation energy was 39.16 kJ/mol. And the thermal degradation reaction was endothermic non-spontaneous reaction. The temperature should be controlled at a degree of no more than 40 ℃ or the pH should be controlled at a value around 2.0 when using red cabbage anthocyanins to process products and excipients that improves or do not affect the stability of anthocyanins should be selected. The product should be processed and stored at a dark environment.