Kinetics Reaction of Caffeine and Chlorogenic Acids Reduction of Robusta Coffee Beans by Steaming in Closed Systems

This study was aimed to examine the correlation between temperature and duration of steaming on caffeine and chlorogenic acid reduction as well as to determine energy activation ( Ea) according to Arrhenius equation. About 750 g of Robusta coffee was steamed by autoclaving at 100, 110, 120 degrees C for 1, 2, 3, 4, 5, 6 and 7 hours. The study was conducted in 3 replications. Analyses of caffeine and chlorogenic acid were performed using HPLC. Steaming coffee beans at 100, 110 and 120 degrees C resulted in the highest decrease of caffeine and chlorogenic acids content for 7 hours by 13%, 18% and 25% for caffeine; and by 37%, 50% and 59% for chlorogenic acids. At all temperatures investigated, decaffeination and chlorogenic acid reduction followed first order reaction. The decaffeination equation at 100 degrees C, 110 degrees C and 120 degrees C followed equation of y = - 0.019x + 0.862, y = - 0.023x + 0.820, and y = - 0.033x + 0.759, respectively. Meanwhile, the chlorogenic acid reduction at 100 degrees C, 110 degrees C, and 120 degrees C followed equation of y = - 0.071x + 1.421, y = - 0.089x + 1.271, and y = - 0.120x + 1.201. Activation energies of decaffeination and chlorogenic acid reduction were 33,543.66 kJ/mol K and 31,934.91 kJ/mol K, respectively.