Heart of palm (Bactris gasipaes Kunth.): mineral composition and kinetics of oxidative enzymes

Analysis of oxidative enzymes such as peroxidase (POD) and polyphenoloxidase (PPO) and the control of the activity of these enzymes are important in food preservation and also in food processing. The aim of this work was to determine polyphenoloxidase (PPO) and peroxidase (POD) enzymatic activity in heart of palm, as well as to evaluate enzyme behavior during thermal treatment, determining the kinetics of thermal inactivation of the heat resistant and heat labile portions. For the extraction of peroxidase (POD) and polyphenoloxidase (PPO) from the heart of palm solution, 100 mM sodium phosphate buffer with different PH values (5.5; 6.0; 6.5 and 7.0) was used. Optimum PH for extraction was 5.5 and 6.5, for POD and PPO, respectively. These extracts were treated at different temperatures (65, 70, 75 and 80 degrees C for periods of I to 10 minutes. Decreases in POD and PPO activities of around 70 and 80%, respectively, in relation to their initial activities were observed. The activation energies, in the temperatures studied, for the heat labile and resistant portions of peroxidase were 154.0 and 153.0 kJ.mol(-1), and of polyphenoloxidase, 26.3 and 27.0 kJ.mol(-1), respectively. The results showed values that are in the range for activation energy reported for the thermal inactivation process of enzymes.