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.