Comparison of polyphenol oxidase activity in fresh tea, apple and potato.

The activities of polyphenol oxidase achieved from apple, fresh tea and potato were determined using spectrophotometer.Results showed that the optimum pH value of polyphenol oxidase achieved from apple, fresh tea and potato were 5, 6 and 7, respectively.And their optimum temperatures were 25 ℃, 30 ℃ and 30 ℃, respectively.The optimum concentrations of PVPP were 0.75 g, 1.05g and 0.45 g, respectively.The optimum substrate concentrations for the three kinds of polyhenol oxidase were 0.12 mol/L, 0.12 mol/L and 0.12 mol/L, respectively.Fresh tea PPO showed the highest thermal stability, followed by apple PPO and potato PPO.The sequence of PPO activities from different sources was:potato Apple fresh tea.