Preliminary Studies On The Chromatographic Fingerprint And Feature Recognition Of Tea Aroma

With wide application of the original certificated system for tea products in China, more and more famous tea joined in this system for protection. There have been already several reports about using chemical fingerprints of famous tea to distinguish quality and indentify their original producing area. This paper aims at applying this method which can distinguish quality and indentify tea original producing area. By using HS-SPME/GC-MS method for extracting and analysis aroma compounds of dry tea, aroma fingerprints of Wuyuan green tea and Wuyi Rock tea are established and the aroma characteristics of Oolong tea from different areas are analyzed. The results are as follows:1. The suitable temperature of SPME is 80℃for green tea, Wuyi Rock tea and black tea, while 60℃for that of Tieguanying tea, respectively. This temperature difference is related to the baking temperatures of them in the final stage during manufacture. Under the same SPME conditions, there are no significant differences in componenents of aroma of tea by hot water brewing or by air heating.2. At optimal conditions of SPME/GC-MS methods aroma of dry tea are extracted and analyzed. Aroma fingerprints of Wuyuan green tea and Wuyi Rock tea were established which can characterize their aroma characteristics. Aroma fingerprints of tea samples can be used to distinguish quality and indentify original producing area by investigating the indexes of finger peaks including relative time, the relative peak area, the similarity coefficient and the overlap rate. This method was simple and reliable.3. Aromas of tea from different areas have respective composition characteristics. Each types of Oolong tea have its own specific aroma components and feature area on the total ion chromatography. The aroma constituents of northern Fujian oolong tea comprise of mainly esters and some baked flavors which is rarely detected in othe type of Oolong tea. It has 12 specific aroma components and one distinguish feature area ('a'area) in the total ion chromatography. Meanwhile, the aroma constituents of southern Fujian oolong tea comprise of mainly alcohols. It has 21 specific aroma components and three distinguish feature areas ('b, c, d'area). The aroma constituents of Guangdong Oolong tea were rich in compounds with flower flavor. Nine specific aroma components were detected and one distinguish feature area ('e'area) was found in aroma constituents of Guangdong Oolong tea. According to specific aroma components, feature areas, content ratio of Farnesene to (E)-Nerolidol, aroma pattern similarity, hierarchical graph of tea aroma compounds, six tea samples can be divided into three types, which are consistent with their original producing area.