Polyphenol oxidase (PPO) was extracted from lotus (Nelumbo nucifera) root and partially
purified up to 11.51× with a 43.6% yield using aqueous two-phase separation system. The
optimum pH was at 8.0 for both substrates; 4-methylcatechol and pyrogallol. PPO activities
were maximally achieved at 50°C for pyrogallol, and 20°C for 4-methylcatechol. 84% and 71%
loss of relative PPO activities were obtained for pyrogallol and 4-methylcatechol, respectively
following heat inactivation at 90°C for 40 min. Inactivation rate constant (k) values ranged
between 0.88 × 10-2 min-1 to 2.97 × 10-2 min-1 for pyrogallol, and 0.69 × 10-2 min-1 to 2.44 × 10-2min-1 for 4-methylcatechol. The activation energy (Ea) were 75.32 kJ mol-1 and 73.14 kJ mol-1
for pyrogallol and 4-methylcatechol, respectively. PPO activity was strongly inhibited (> 79%)
by ascorbic acid. SDS exhibited the greatest efficiency in activating lotus root PPO.