Effect of Anaerobic Treatment Time on Quality of Greenand Black Teas

The one bud andtwo fresh leaves from Fuding Dabaicha（Camellia sinensis）, Huangjinya（Camellia sinensis）, and Baiye 1（Camellia sinensis） plants were processedwith different lengths of anaerobic treatment time (0, 2, 4, and 8h) toencourage GABA formation in the tea products. The regular processes to producegreen tea and black tea were followed to make different samples for this study.Contents of GABA and major chemical components in the tea samples made underthe varied treatment times in a vacuumized chamber were compared. It was foundthat the experimental green and black teas had the contents of GABA and freeamino acid significantly increased, tea polyphenols and water extractdecreased, and caffeine changed slightly by prolonged anaerobic exposure. Undera same anaerobic treatment time, the black tea contained significantly moreGABA than the green tea, and the enrichment was more pronounce in the caseswhere the leaves from high amino acid tea varieties were used as the rawmaterial. For instance, Huangjinya had the highest GABA contents of 2.69 mg·g^-1 in the anaerobically treated green tea and 2.64 mg·g^-1 in the blacktea. In the end, the treatment of 0.09MPa vacuum at 25°C for 4 hours, either alongwith fixation at 180°C on raw leaves of 300g to blanch for 2 min making the greentea or a fermentation at 28°C with RH at 90% in processing the black tea, couldrender the most desirable products. The obtained green tea was judged to berichly fragrant with a refreshing taste, and the black tea long-lasting aromaticwith a mellow flavor, while both met the standard on GABA content.