Peroxidase and Polyphenoloxidase Activities in Papaya During Postharvest Ripening and After Freezing/Thawing

Changes in peroxidase (POD) and polyphenoloxidase (PPO) activities of papaya ( Caricu papava ), cv Sunrise, during ripening, freezing and short frozen storage were studied. Fruits were stored at 14°C and 85 90 % RH until maturity for processing was reached (about 21 days). Fruit were frozen cryogenically and frozen slices were stored at — 18°C. POD activity increased in pulp tissue up to the ripe stage, showing a maximum value after 7 days cold storage. Similarly, PPO activity showed an important increase (4 × initial value) on the same date. The quantity of extractable proteins was at a maximum after 15 days storage at 14°C. Freezing and frozen storage (‐18°C) produced an increase of POD activity while EPO activity was only slightly affected.