Kinetic Analysis of Stabilizing C-Phycocyanin in the Spirulina platensis Extracts from Ultrasonic Process Associated with Effects of Light and Temperature

A kinetic model was developed to reflect the stability of C-Phycocyanin (C-PC) from ultrasonic extraction process under different storage conditions. The decrease of C-PC contents was most accelerated at a high temperature of 40 °C along with light illumination, resulting in ca. 60% drop of an initial concentration for two months of storage. However, ca. 93% of the initial contents remained at 4 °C without light, which would be a most favorable condition for long-term storage. It was first shown that the decrease of the residual concentrations followed second-order kinetics under light illumination. However, without light, the decrease of the C-PC contents showed first order reaction kinetics, which implies initial C-PC concentrations are important. On the contrary, initial storage temperature seemed to be more influential under light illumination. It was also first revealed that the rate of degrading the C-PC was faster with light than without light even at the same temperature, having 0.0108 (1/h) and 0.0138 (1/h) of rate constants of first order (no light) and second order kinetics (with light) at 40 °C, respectively. Moreover, the cleavage of C-PC was also found to follow the Arrhenius relationship. Therefore, this work could provide desirable storage conditions of C-PC from non-thermal ultrasonic process for long-term storage.