Partial purification and characterization of polyphenol oxidase from persimmon

Area of Science:

• Enzymology
• Food Science
• Biochemistry

Background:

• Polyphenol oxidase (PPO) is a key enzyme responsible for enzymatic browning in fruits.
• Understanding PPO activity and stability is crucial for preventing post-harvest losses in persimmons.

Purpose of the Study:

• To characterize the activity and stability of PPO from "Rojo Brillante" persimmon fruits.
• To investigate the effect of pH, temperature, and substrate concentration on PPO.
• To explore PPO isoforms and their potential role in browning.

Main Methods:

• Enzyme activity and stability assays using crude persimmon fruit extracts.
• Characterization of PPO activity across a range of temperatures (60-80°C), pHs (3.5-7.5), and catechol concentrations (0-0.5M).
• Polyacrylamide gel electrophoresis (PAGE) to identify PPO isoforms.

Main Results:

• Maximum PPO activity was observed at pH 5.5 and 55°C.
• The enzyme demonstrated significant stability, with 90% inactivation requiring 70 min at 80°C above pH 5.5.
• Enzyme stability decreased significantly at pH 4.0, with >90% inactivation within 10 min at 60°C.
• PAGE revealed at least four distinct PPO isoforms with oxidase activity.

Conclusions:

• Acidification of persimmon fruits can effectively inhibit PPO activity, thereby preventing browning.
• The presence of multiple PPO isoforms suggests complex enzymatic mechanisms in persimmon browning.
• The characterized PPO from "Rojo Brillante" persimmon exhibits notable stability, with potential implications for food processing and preservation strategies.