July 04, 2026 | Vegetos | Idris
This study conducted by the Federal University of Technology, Nigeria investigated the biochemical characteristics of polyphenol oxidase (PPO), the key enzyme responsible for enzymatic browning in breadfruit (Artocarpus altilis). Although breadfruit is a nutritious tropical fruit with considerable food and commercial potential, rapid browning after harvest reduces its quality, marketability, and processing value. Natural inhibitors could provide a safe and sustainable approach to minimizing this problem.
The researchers purified PPO from breadfruit and examined its physicochemical properties, enzyme kinetics, and responses to different environmental conditions and natural fruit extracts. The enzyme showed maximum activity at pH 5.0 and 40 °C and exhibited the highest affinity for catechol as a substrate. PPO activity decreased substantially under acidic conditions and at high temperatures, indicating that the enzyme is unstable outside its optimal range. Several compounds, including magnesium, calcium, EDTA, and glycine, also inhibited enzyme activity.
The study further demonstrated that lemon extract acted as a competitive inhibitor of PPO, while onion extract inhibited the enzyme through a non-competitive mechanism, indicating different modes of action. These findings improve the understanding of enzymatic browning in breadfruit and suggest that natural, food-grade extracts could be used to reduce browning during postharvest handling and processing, thereby improving fruit quality and shelf life.
