Polyphenoloxidase activity, browning potential and phenolic content of peaches during postharvest ripening

Changes in the polyphenoloxidase (PPO) activity and the phenolic content of peaches (Prunus persica cv. Premier) during postharvest ripening were studied. The fruits were stored at 12 or 25C for up to 15 days. The quantity of extractable proteins was maximum at 6-10 days storage at 25 and 12C, coinciding with the onset of the yellowness in the fruits. The PPO activity increased up to the ripening stage, showing a maximum value at 8 days of storage. This was coincident with the maximum degree of browning as evaluated by the absorbance at 440 nm. The amount of total phenolics and chlorogenic acid in the fruits decreased during storage; however, the differences were not significant. The browning potential closely correlated with the enzyme activity, but not with the phenolic content.