Polyphenoloxidase Activity of Pear (cv. Rocha) Reduced by Controlled Atmosphere Storage

The enzymatic browning of fruits during storage may cause undesirable quality changes, specially of colour. During storage of fruits, polyphenoloxidase (PPO) activity and browning were reported by several authors to vary in different ways, depending on species, cultivar, picking maturity, storage conditions, etc (Amiot et al., 1992). PPO soluble content and browning were, in most cases, found to increase during normal atmosphere. According to Burton (1982), since phenolases have a low oxygen-affinity, oxidation of phenolic substrates can be avoided or at least reduced at 02 levels of 5% or less. Therefore, the use of controlled atmosphere (CA) storage may succeed to reduce these processes. Although there are studies in literature on PPO of pears (Espfn et al., 1997; Halim and Montgomery, 1978; Smith and Montgomery, 1985; Zhou and Feng, 1992), very scarce, if none, information is available on PPO of 'Rocha' pear. The objective of this work was to evaluate the effects of controlled atmosphere storage (low oxygen and carbon dioxide contents) on PPO activity of 'Rocha' pear, in comparison to storage in normal atmosphere.