Effects of Raw Materials from Different Tea Cultivars of Leaf Colour on Sichuan Dark Tea Quality

To explore the influence of raw materials from different cultivars on the quality of Sichuan dark tea, the raw materials of 4 tea cultivars were used in this study. The main chemicals and aroma components were analyzed by sensory evaluation, chemical analysis and gas chromato graphy-mass spectrometry (GC-MS) . The main components of Sichuan dark teas made from different tea cultivars were significantly different. The contents of water extract, tea polyphenols, catechins and caffeine of Sichuan dark teas from 'Zijuan' were the highest, which were 49.45%, 18.54%, 4.77%, and 4.21%, respectively, followed by Sichuan dark tea processed with 'Huangjinya' cultivar, all of them were significantly (P<0.05) higher than the Sichuan dark tea processed with 'Fuding Dabai' and 'Baiye 1'. The contents of L-asparagine, L-theanine, aspartic acid and glutamic acid were the highest of Sichuan dark teas from 'Huangjinya', which were 115.78, 279.86, 154.47, 70.76 mg/100 g, respectively, significantly (P<0.05) higher than Sichuan dark tea processed with other cultivars. Aroma analysis showed that main aroma components were alcohols, aldehydes, ketones, hydrocarbons and esters, accounting for more than 80% of the total aroma. The similarity rate of aroma between 'Fuding Dabai' and 'Baiye 1' was 0.98, and that of 'Huangjinya' and 'Zijuan' was 0.99. The Sichuan dark tea processed with the 'Baiye 1' had floral fragrance, and the Sichuan dark tea processed with the 'Zijuan' had ''stale flavor''. Sensory quality analysis showed that the comprehensive qualities of Sichuan dark teas from 'Fuding Dabai'，'Baiye 1' and 'Huangjinya' were the better, with a score of more than 82, while the Sichuan dark tea from 'Zijuan' had the lowest score. The Sichuan dark tea processed with 'Huangjinya' materials was rich in substances and had good comprehensive quality. The Sichuan dark tea processed with 'Baiye 1' material had floral fragrance, which could be used as a variety for processing advanced special Sichuan dark tea. The Sichuan dark tea processed with 'Zijuan' materials had high content of water extracts and tea polyphenols, with ''stale flavor''. It was suitable for blending and processing with other cultivars of low polyphenol content, and could be used as a blending variety for dark tea products with ''stale flavor''.