Abstract: The effect of the ultrahigh pressure processing(UHPP)on the cell structure,PPO activity and main chemical composition of fresh tea leaves was studied.Results showed that:① Under the 600 MPa pressure,the cellular structure of fresh tea leaves shrink obviously,and the cell sap overflow distinctly.② The relative activity of PPO was remarkably decreased under the UHPP over 500 MPa holding for 10 min at 37 ℃.③ Under the treatment of 500 MPa holding for 5 min,the content of tea polyphenols and amino acids in fresh tea leaves was 9.14% and 1.35% respectively,increased 24% and 42% compared with the control.④ UHPP can also accelerated the overflow of chlorophyll and carotenoids from the chloroplast,but the excessive high pressure and the longer process time would cause the content decrased to some extent.

Key words: ultrahigh pressure, fresh tea leaves, cell structure, PPO, tea polyphenols, amino acids, chlorophyll