Variation of major volatile constituents in various green teas from southeast Asia

A total of 15 green tea samples were prepared fi om fresh tea leaves obtain ed from three different countries: two from Laos, seven from Myanmar, and s ix from Vietnam. The volatile aroma. constituents of the 15 samples were an alyzed by gas chromatography/mass spectroscopy. Eleven aroma constituents w ere chosen from over 100 chemicals found in the samples to compare differen ces among various teas. They were hexanal, 1-penten-3-ol, heptanal, 1-pente nal, (Z)-2-penten-1-ol, (Z)-3-penten-1-ol, linalool oxide (trans-furanoid), linalool oxide (cis-furanoid), linalool, linalyl propanoate, and geraniol. Generally, concentrations of linalool and hexanal seem to play an importan t role in the quality of green teas. Green teas from Laos and Myanmar conta ined heterocyclic compounds, such as pyridines and pyrazines, formed by hig h-temperature processing. The presence of these heterocyclic compounds sugg ested that the temperature used for tea processing plays an important role in the formation of aroma chemicals in green teas.