Peroxidase is an iron-containing enzyme capable of oxidizing phenolics to quinones in the presence of hydrogen peroxide.
Like PPO, the physiological role of peroxidase in plants is not well understood but it has been implicated in a number of primary and secondary metabolic functions including lignin biosynthesis, ripening and senescence, ethylene biosynthesis, hormone balance, and membrane
integrity (Vamos-Vigyazo, 1981).
Lagrimini (1991) produced transformed tobacco plants overexpressing peroxidase which showed rapid browning in response to wounding, but the role of peroxidase in normal enzymic
browning is still not well established.