Stabilization of Chlorophyll in Collard Greens and Parsley Juice Using Different Agents: A Kinetic Study

This study aimed to obtain a more stable colored product by slowing down chlorophyll degradation in collard greens and parsley juices, which are rich in chlorophyll. For this purpose, four different stabilizing agents (l-ascorbic acid, Tween 20, ZnCl₂, and xanthan gum) were added separately at three different concentrations to collard greens and parsley juices. Kinetic and thermodynamic parameters of chlorophyll degradation kinetics were then calculated. The results showed that the initial chlorophyll content significantly influenced the degradation kinetics, with collard greens showing higher degradation rates than parsley. The activation energy values of chlorophyll degradation in stabilized juices (18.16–82.48 kJ/mol) are generally lower than those of control samples (71.73 kJ/mol), indicating that stabilized juices are less sensitive to temperature changes. The highest z value (77.1 K) in collard green juice was observed in the sample stabilized with 0.01% xanthan gum, while 0.5% ascorbic acid gave the highest z value (131.5 K) in parsley juice. Thermodynamic parameters (∆H^# 15.2–74.8 kJ/mol; ∆S^# −247.9 to −79.9 J/mol K; ∆G^# 100.6–130.3 kJ/mol) showed that chlorophyll degradation is endothermic and has an entropy barrier. Furthermore, stabilizers did not alter the chlorophyll degradation pathway. 0.5% ascorbic acid and 0.1% Tween 20 are recommended as stabilizing agents to minimize chlorophyll degradation during heat treatment.