Thermal inactivation of strawberry (Fragaria ananassa) polyphenoloxidase--a kinetic study
Dalmadi, I.; Rapeanu, G.; Van Loey, A.; Smout, C.; Hendrickx, M.
Communications in Agricultural and Applied Biological Sciences 69(2): 77-80
2004
ISSN/ISBN: 1379-1176 PMID: 15560192 Document Number: 574019
The thermal inactivation of strawberry cv. Elsanta polyphenol oxidase (PPO) was studied at temperatures ranging from 25 to 80 degrees C. Ten minutes heating at 55 degrees C reduced the PPO activity in strawberry extract by 44%. The enzyme was almost completely inactivated at 65 degrees after 10 minutes of thermal treatment. The inactivation rate constant for the labile and stable PPO fraction of strawberry PPO extract at 60 degrees C were 1.78 and 0.14/minute, respectively. The thermostable PPO fraction contributed about 44-55% of the total activity of the enzyme. The inactivation rate constants of the labile and stable fractions increased with increasing temperature.