A comprehensive review of polyphenol oxidase in tea (Camellia sinensis): Physiological characteristics, oxidation manufacturing, and biosynthesis of functional constituents

Polyphenol oxidase (PPO) is a metalloenzyme with a type III copper core that is abundant in nature. As one of the most essential enzymes in the tea plant (Camellia sinensis), the further regulation of PPO is critical for enhancing defensive responses, cultivating high-quality germplasm resources of tea plants, and producing tea products that are both functional and sensory qualities. Due to their physiological and pharmacological values, the constituents from the oxidative polymerization of PPO in tea manufacturing may serve as functional foods to prevent and treat chronic non-communicable diseases. However, current knowledge of the utilization of PPO in the tea industry is only available from scattered sources, and a more comprehensive study is required to reveal the relationship between PPO and tea obviously. A more comprehensive review of the role of PPO in tea was reported for the first time, as its classification, catalytic mechanism, and utilization in modulating tea flavors, compositions, and nutrition, along with the relationships between PPO-mediated enzymatic reactions and the formation of functional constituents in tea, and the techniques for the modification and application of PPO based on modern enzymology and synthetic biology are summarized and suggested in this article.

Automated summary

Polyphenol oxidase (PPO) is a metalloenzyme in tea plants that plays a crucial role in enhancing defensive responses, cultivating high-quality germplasm resources, and producing functional tea products. The oxidative polymerization of PPO in tea manufacturing can provide functional foods for preventing and treating chronic non-communicable diseases. However, more comprehensive research is needed to understand the relationship between PPO and tea. This article provides a comprehensive review of the classification, catalytic mechanism, and utilization of PPO in modulating tea flavors, compositions, and nutrition, as well as the techniques for modifying and applying PPO based on modern enzymology and synthetic biology.