Authors : Li-Zhang Fan, Meng Zhang, Dan Wang and Shao-Xiong Ren
Abstract: The activity of feijoa fruit Polyphenol Oxidase (PPO) was determined by spectrophotometer at 420 nm using catechol as substrate.The effects of the pH, temperature, substrate concentration and inhibitors on PPO were studied. A range of pH 3.0-8.0 was tested and the highest enzyme activity was at pH 5.5. The optimum temperature was determined by measuring the enzyme activity at various temperatures over the range of 10-70°C with 10°C increments. The optimum temperatures were found to be 30°C. The Vmax and Km value of the reaction were determinedand found to be 137 U min-1 protein and 0.38 mM. The three inhibitors as ascorbic acid, NaHSO3 and EDTA had different effects on inhibiting enzymatic browning. Inhibitors used for investigation in this study were placed in relative order of inhibition: NaHSO3>ascorbic acid>EDTA.
Li-Zhang Fan, Meng Zhang, Dan Wang and Shao-Xiong Ren, 2012. Characterization of Polyphenol Oxidase from Feijoa Fruit. Agricultural Journal, 7: 323-326.