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<p>This study aimed to evaluate the effects of microwave (MW), ultrasonic (US), and thermosonic (TS) treatments on the inactivation of polyphenol oxidase (PPO) and peroxidase (POD) enzymes as well as on the phytochemical components (total phenolic content [TPC], total flavonoid content [TFC], and antioxidant activity [AA]) of green tea leaves. The performance of these treatments was also compared with conventional steam blanching (SB). The results showed that POD exhibited greater resistance to thermal and ultrasonic effects compared to PPO. Among the treatments investigated, MW (900 W) achieved approximately 80% inactivation of both enzymes (PPO: 7.94 ± 1.14 U g<sup>−1</sup> FW<sup>−1</sup>; POD: 1.22 ± 0.22 U g<sup>−1</sup> FW<sup>−1</sup>) within a short time (90&#xa0;s) with higher retention of phytochemical components and surface color. While US treatment exhibits limited enzymes’ inactivation but increased TPC and TFC compared to other treated and untreated (fresh) samples. SB was more effective in inactivating PPO (4.28 ± 0.59 U g<sup>−1</sup> FW<sup>−1</sup>) than POD (3.40 ± 0.37 U g<sup>−1</sup> FW<sup>−1</sup>) after 6&#xa0;min of treatment time and resulted in satisfactory AA (93.18 ± 0.22%). Among the assessed kinetic models, the Weibull distribution model best fits both enzymes’ inactivation data, showing highest <i>R</i><sup>2</sup> and lowest RSME values compared to the distinct isozymes and first-order kinetic models. Overall, findings suggest that MW treatment could be a promising alternative for enzyme inactivation in green tea leaves, with better retention of bioactives than conventional SB.</p>

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Enzymes Inactivation Kinetics and Phytochemical Retention in Green Tea Leaves: A Comparative Study of Microwave, Thermosonic, and Conventional Treatments

  • 期刊论文

  • 发表日期：

    2026年1月9日

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  • Barsha Borah,
  • Duyu Nampi,
  • Varun Kumar,
  • Sandhya R. Shewale,
  • Deependra Rajoriya

摘要

This study aimed to evaluate the effects of microwave (MW), ultrasonic (US), and thermosonic (TS) treatments on the inactivation of polyphenol oxidase (PPO) and peroxidase (POD) enzymes as well as on the phytochemical components (total phenolic content [TPC], total flavonoid content [TFC], and antioxidant activity [AA]) of green tea leaves. The performance of these treatments was also compared with conventional steam blanching (SB). The results showed that POD exhibited greater resistance to thermal and ultrasonic effects compared to PPO. Among the treatments investigated, MW (900 W) achieved approximately 80% inactivation of both enzymes (PPO: 7.94 ± 1.14 U g−1 FW−1; POD: 1.22 ± 0.22 U g−1 FW−1) within a short time (90 s) with higher retention of phytochemical components and surface color. While US treatment exhibits limited enzymes’ inactivation but increased TPC and TFC compared to other treated and untreated (fresh) samples. SB was more effective in inactivating PPO (4.28 ± 0.59 U g−1 FW−1) than POD (3.40 ± 0.37 U g−1 FW−1) after 6 min of treatment time and resulted in satisfactory AA (93.18 ± 0.22%). Among the assessed kinetic models, the Weibull distribution model best fits both enzymes’ inactivation data, showing highest R2 and lowest RSME values compared to the distinct isozymes and first-order kinetic models. Overall, findings suggest that MW treatment could be a promising alternative for enzyme inactivation in green tea leaves, with better retention of bioactives than conventional SB.