Effect of high-hydrostatic-pressure processing on catechin content in green tea leaves

ABSTRACT

Green tea catechins can improve human health, and their retention during processing is a concern. High hydrostatic pressure (HHP) blanching is a nonthermal processing that can increase both nutrients and flavor in tea. Thermal blanching retains catechins but decreases nutrients and flavor. We investigated catechin retention potency via HHP and thermal treatment. Fresh green tea leaves were pressurized at 100–800 MPa and/or heated for 10 min at 40°C–70°C and then stored for 24 hours. Tea catechin content was drastically reduced after storage without HHP, which yielded a 1.5–8.0-fold increase. HHP showed a smiling curve relationship with catechin retention, with the highest levels found at 200 and 800 MPa. Synergistic effects of HHP on thermal processing were found at 40°C–50°C but not at 60°C–80°C. Processing at 200 MPa combined with 50°C yielded 88% catechin retention. Our results suggest this combination as an optimal strategy for retaining tea catechins, nutrients, and flavor.

KEYWORDS:

• Catechins
• degradation
• green tea
• high-pressure processing
• nonthermal processing

Acknowledgments

We would like to express our special thanks and gratitude to Professor Asuma and Senior Lecturer Yamada at Utsunomiya University for providing the experimental equipment. We would also like to thank the Kishida family green tea farm and Odudumien in Saitama, Japan, for providing fresh green tea leaves as samples.

Disclosure statement

No potential conflict of interest was reported by the author(s).

Additional information

Funding

This work was supported by Japan Society for the Promotion of Science.