Thermal degradation kinetics of vitamin C in jujube juice

In order to investigate the effect of temperature on the vitamin C in jujube juice and decrease the loss of vitamin C in the processing of jujube juice, the thermal degradation kinetics of Ascorbic Acid(AA) at 303, 313, 323, 333 and 343 K in the clarified jujube juice were investigated, and a mathematical model to predict Dehydroascorbic Acid(DHAA) concentration was also established. Activation energies of AA and DHAA degradation were calculated by Arrhenius equation. The results showed that the loss of AA at each temperature followed the reversible first-order kinetic model and all r-squared values were higher than 0.98. The kinetic model of DHAA was fitted to its degradation in jujube juice. Both AA and DHAA in the jujube juice decreased with increasing temperature, however, the rate of AA degradation was higher than that of DHAA for its low activation energy, and degradation of DHAA occurred after AA being in equilibrium. The present study can be applied to optimize the processing technology of jujube juice and improve its quality.