Abstract:

The effect of tartaric acid treatment at various concentrations on relative activity, thermostability and
thermosensitivity of polyphenol oxidase (PPO) from the edible mushroom Agaricus bisporus was studied. The results
showed that the relative activity of PPO decreased gradually with increasing tartaric acid concentration and was only 1.41%
of its original activity when the tartaric acid concentration was up to 40 mmol/L. In addition, the thermostability of PPO
decreased, and the inactivating effect of tartaric acid combined with heat was enhanced. Inactivation rate constant (k) of PPO
increased with increasing tartaric acid concentration, and the k values were 1.43 × 10-2, 2.43 × 10-2, 6.78 × 10-2, 57.61 ×
10-2 min-1, respectively when the tartaric acid concentrations were 0, 10, 15 and 20 mmol/L at 50 ℃, while the activation
energy (Ea) showed the opposite trend, which was calculated to be 191.57, 180.05, 140.64 and 67.93 kJ/mol, respectively,
when the tartaric acid concentrations were 0, 10, 15 and 20 mmol/L, suggesting weakened thermosensitivity of PPO.

Key words: polyphenol oxidase, tartaric acid, relative activity, thermostability, thermosensitivity