*3.5. Enzymes Activity Levels*

Enzyme activity levels are presented in Figure 8A,B. Polyphenol oxidase (PPO) and peroxidase (POD) activity levels significantly increased in all treatments with storage time. The highest activity levels for PPO and POD were found in control treatment at days 6 and 9. Generally, at the end of the storage period, PPO and POD activity levels were higher in OPP packages than PE packages. The longest shelf life times were obtained for OPP-20 and OPP-40 packages with no difference in PPO and POD activity levels, with few exceptions (Figure 8A,B).
