TEMPERATURE-DEPENDENT KINETICS OF ANTHOCYANINS EXTRACTION FROM RED ROSE PETALS

Abstract

The red rose is one of the perspective natural resources of anthocyanins, however kinetic study for anthocyanins extraction of red rose petals is not yet elucidated. Red rose petals were dried at 303 K and ground (particle size ~ 5 mm). The petals were extracted by aqueous acid solutions using conventional solid-liquid extraction. The efficiency of 0.1 M aqueous solutions of acids as extractants towards red rose anthocyanins was studied and it can be arranged in the following row: citric acid < acetic acid < hydrochloric acid. Kinetic investigations focusing on the temperature effect on solid-liquid extraction of anthocyanins from petals of red rose were performed at three temperatures (293, 313, and 333 K). Kinetic curves were obtained using an aqueous solution of hydrochloric acid. It was found that the rate of extraction of anthocyanins was very fast at the beginning, but it began to slow down after 60 minutes for all temperatures. The experimental kinetic curves of the extraction of anthocyanins at different temperatures were obtained and analyzed using common empirical kinetic models (the first-order, second-order kinetic models, the Peleg model, and the power-law model). The second-order kinetic model provided the best agreement with the experimental results in terms of statistical parameters (coefficient of determination (R2) and average relative error (ARE)) than other studied models. As temperature increases, the second-order rate constant values and the initial extraction rate values also increased. The second-order rate constants were used to evaluate the activation energy of extraction. The calculated activation energy of the anthocyanin extraction is 39.3 kJ/mol, which is an indication of an endothermic process. Obtained data can be used to predict the extraction of anthocyanins from red rose petals.