Effect Of Ultra High Pressure Treatment On Main Tea Quality Components And Ingredients

The ultrahigh pressure processing (UHPP), a new high-tech for food processing, has received considerable attention recently in the field of food processing, while it never be studied in the field of tea processing. Based on its technical characteristics, the changes of cell structure, PPO activity and main chemical composition of fresh tea leaves under the UHPP were studied, the possibility of UHPP used in tea processing was also be investigated in this study. The objectives of this study are to innovate the traditional tea processing technology and to develop new tea products.1. Effect of UHPP on the cell structure, PPO activity and main chemical composition of fresh tea leaves was studied. Results showed that: (1) Under the 600Mpa 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 500MPa holding for 10 min at 37℃. (3)Under the treatment of 500MPa 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 from the chloroplast, but the excessive high pressure and the longer process time would cause the content decrased to some extent.2. Application of UHPP on green tea processing was investigated. The result showed that: (1) The UHPP on fresh tea leaves can improve the organoleptic quality of made green tea. (2) Using UHPP on fresh tea leaves before the de-enzyme can make green tea the best taste and aroma, especially increasing the content of linalool. (3) The UHPP over 500MPa holding for at least 10 min is necessary to make green tea with better aroma and taste compared with the control. (4) For the whole quality of made green tea, using UHPP on fresh tea leave one time is better than several times.3. Application of UHPP on black tea processing was studied. Results showed that: (1) The UHPP is more suitable to make CTC black tea than to make leaf black tea. (2) The best processing procedure for CTC black tea is fresh tea leaves→UHPP (550MPa,10min)→withering in room temperature for 4h→cutting→fermenting for 30min→drying. (3) The UHPP can obviously improve the aroma composition of CTC black tea, in which the content of alcohols, esters and aldehydes increased, and the part of alkanes decreased.