Thermal degradation kinetics of anthocyanins from red cabbage

The thermal stability and degradation kinetics of anthocyanins from red cabbage at different temperatures and pH values were investigated. The anthocyanins from red cabbage were extracted by 80% ethanol aqueous solution and then purified with D-101 macroporous adsorption resin. Within the temperatures range of 50,60,70,80 ℃,the anthocyanins contents at different time points were measured at different pH(2.0~6.0)to investigate its thermal degradation kinetic parameters and browning index. Results showed that the thermal stability of anthocyanins from red cabbage was influenced by temperature and pH. The degradation rate was in good linear relation with time and followed first order reaction kinetics. With the increasing of temperature,the half-life(t_1/2)at different pH were declining,in which the maximum value was 83.51 h(50 ℃,pH3.0)and the minimum values was 4.43 h(80 ℃,pH6.0),and the activation energy(E_a)of reaction systems(pH2.0~6.0)were 42.30,45.31,38.85,26.83 and 31.20 kJ/mol,respectively. Besides,the browning index increased with the extension of heat treatment time and the increase of temperature and pH.