Several chemical and physical anti-browning agents are studied in different model systems in which caffeic acid (as substrate) and laccase from Trametes versicolor (LAC) and polyphenoloxidase from sunflower seeds (PPO) (as enzymes) are used to emulate the browning reaction. Temperature and low electric current were the tested physical agents, while acetic acid, sodium acetate, sodium chloride and, finally, sodium bisulfite were the chemical agents. Sunflower PPO was observed to be less heat sensitive than LAC that was fully inactivated after 1 and 3 min of exposure to 100 and 80 A degrees C, respectively. Conversely, PPO required more than 3 min at 100 A degrees C to be fully inactivated, and it still showed a significant activity (ca. 17%) after an exposure to 80 A degrees C for 15 min. Both LAC and PPO were found to be active at frozen (-18 A degrees C) and cool (+4 A degrees C) temperature, and their activities were strengthened at 40 and 60 A degrees C. As concerning chemical agents, inhibitory power of acetic acid on LAC was observed to be very weak. In the sodium acetate solution at the concentrations of 0.5, 1.0, 2.0 and 4.0%, LAC residual activity was equal to 81.5, 63.9, 61.1 and 35.2%, respectively. PPO is shown to be more sensitive to the NaCl than LAC and indifferent to the presence of NaHSO(3). A 28% residual activity of LAC was found in the solution with 200 mg L(-1) NaHSO(3). Finally, LAC activity was decreased to 72.3, 60.0, 16.7 and 8.4% after a low electric current (LEC) treatment of 30 s and 1, 3 and 6 min, respectively. Conversely, PPO activity was not affected under these conditions.

Application of chemical and physical agents in model systems to controlling phenoloxidase enzymes

Antonella, De Leonardis
;
Giuseppe, Lustrato;Vincenzo, Macciola;Giancarlo, Ranalli
2010

Abstract

Several chemical and physical anti-browning agents are studied in different model systems in which caffeic acid (as substrate) and laccase from Trametes versicolor (LAC) and polyphenoloxidase from sunflower seeds (PPO) (as enzymes) are used to emulate the browning reaction. Temperature and low electric current were the tested physical agents, while acetic acid, sodium acetate, sodium chloride and, finally, sodium bisulfite were the chemical agents. Sunflower PPO was observed to be less heat sensitive than LAC that was fully inactivated after 1 and 3 min of exposure to 100 and 80 A degrees C, respectively. Conversely, PPO required more than 3 min at 100 A degrees C to be fully inactivated, and it still showed a significant activity (ca. 17%) after an exposure to 80 A degrees C for 15 min. Both LAC and PPO were found to be active at frozen (-18 A degrees C) and cool (+4 A degrees C) temperature, and their activities were strengthened at 40 and 60 A degrees C. As concerning chemical agents, inhibitory power of acetic acid on LAC was observed to be very weak. In the sodium acetate solution at the concentrations of 0.5, 1.0, 2.0 and 4.0%, LAC residual activity was equal to 81.5, 63.9, 61.1 and 35.2%, respectively. PPO is shown to be more sensitive to the NaCl than LAC and indifferent to the presence of NaHSO(3). A 28% residual activity of LAC was found in the solution with 200 mg L(-1) NaHSO(3). Finally, LAC activity was decreased to 72.3, 60.0, 16.7 and 8.4% after a low electric current (LEC) treatment of 30 s and 1, 3 and 6 min, respectively. Conversely, PPO activity was not affected under these conditions.
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Utilizza questo identificativo per citare o creare un link a questo documento: http://hdl.handle.net/11695/1337
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