Changes in Sensory Quality and Catechins Content in Tea Extracts as Influenced by Infusion Temperatures and Times
2007
Lee, M.K. (Mokpo National University, Muan, Republic of Korea) | Park, Y.S. (Mokpo National University, Muan, Republic of Korea), E-mail: [email protected]
This experiment was conducted to determine the effects of extracting temperatures and times on sensory quality and catechins content in roasted tea, steamed tea, roasted tea bag (tea bag) and semifermented tea (Camellia sinensis) products. All tea leaves were extracted with hot water (70, 80, 90, or 100℃) 3 times (first, second and third), respectively. In sensory evaluation, astringency and bitterness in roasted and tea bag decreased with increasing extracting temperature, while sweetness and flavour were much lower in both 70 and 100℃ than those of 80 or 90℃. Sensory quality in steamed tea was not affected by extracting temperature except for sweetness. Bitterness and astringency in semifermented tea enhanced in 90℃ compared to 70, 80 or 100℃, but sweetness and flavour did not differ among treatments. Sensory quality slightly decreased with delayed extracting times, especially the third times in all teas. Tannin content increased with raising extraction temperatures and early extracting time in all teas. Content of tannin was highest in roasted tea followed by semifermented tea, tea bag and steamed tea. Eight major catechins were identified in the tea extracts and those contents gradually increased with increasing extracting temperatures and early extracting times, especially the first time. Among tea products, catechins contents were much higher in both roasted tea and tea bag than those of steamed tea or semifermented tea. In conclusion, taste quality improved in tea extracts by both suitably balanced bitterness, astringency, sweetness and catechins contained when teas were extracted at 80-90, 70-90℃ and 90℃ for the first times in roasted tea or tea bag, steamed tea and semifermented tea, respectively.
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