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<p>Breadfruit (<i>Artocarpus altilis </i>) is a nutritious yet underutilised tropical fruit, and its postharvest value is limited by polyphenol oxidase (PPO)-mediated enzymatic browning. This study characterised breadfruit PPO and assessed natural fruit extracts as safe, sustainable anti-browning agents. PPO was purified by ammonium sulphate fractionation and chromatography, and its physicochemical properties and inhibition by natural fruit extracts were evaluated. Purified PPO was a 26.7&#xa0;kDa monomer, optimally active at pH 5.0 and 40&#xa0;°C, and specific for catechol, with <i>K</i><sub><i>m</i></sub> and <i>V</i><sub><i>max</i></sub> of 6.65 mM and 0.085&#xa0;mg/min/mL. Residual activity fell below 10% at acidic pH (4.0 to 6.0) and at high temperatures (80 to 90&#xa0;°C), indicating enzyme instability, while Mg<sup>2+</sup>, Ca<sup>2+</sup> (5 mM), EDTA and glycine strongly inhibited it. Lemon extract inhibited PPO competitively, whereas onion extract acted via a non-competitive mechanism, suggesting active-site and allosteric inhibition. These findings provide a biochemical basis for understanding browning in breadfruit and support the use of natural, food-grade inhibitors for species-specific control of enzymatic browning during postharvest handling and processing.</p>

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Purification, biochemical properties and inhibition of PPO from breadfruit (Artocarpus altilis) by natural fruit juices

  • 期刊论文

  • 发表日期：

    2026年7月4日

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  • Olawole O. Idris,
  • Olusola T. Lawal,
  • Damilola Fasan,
  • Akinyode I. Olopoda,
  • Oluwasegun V. Omotoyinbo,
  • David M. Sanni,
  • Folasade M. Olajuyigbe

摘要

Breadfruit (Artocarpus altilis ) is a nutritious yet underutilised tropical fruit, and its postharvest value is limited by polyphenol oxidase (PPO)-mediated enzymatic browning. This study characterised breadfruit PPO and assessed natural fruit extracts as safe, sustainable anti-browning agents. PPO was purified by ammonium sulphate fractionation and chromatography, and its physicochemical properties and inhibition by natural fruit extracts were evaluated. Purified PPO was a 26.7 kDa monomer, optimally active at pH 5.0 and 40 °C, and specific for catechol, with Km and Vmax of 6.65 mM and 0.085 mg/min/mL. Residual activity fell below 10% at acidic pH (4.0 to 6.0) and at high temperatures (80 to 90 °C), indicating enzyme instability, while Mg2+, Ca2+ (5 mM), EDTA and glycine strongly inhibited it. Lemon extract inhibited PPO competitively, whereas onion extract acted via a non-competitive mechanism, suggesting active-site and allosteric inhibition. These findings provide a biochemical basis for understanding browning in breadfruit and support the use of natural, food-grade inhibitors for species-specific control of enzymatic browning during postharvest handling and processing.