Changes of taste quality and catechins content in tea extracts according to elapsed time an ambient temperature.

摘要

Roasted tea, roasted tea bag (tea bag), steamed tea and semifermented tea leaves (Camellia sinensis) were extracted at 90 degrees C hot water with 3 times replications (first, second and third) for 3 minutes, respectively. After extraction, tea extracts were placed an ambient temperature for 30, 60, 90, 120 and 150 minutes, respectively. In taste quality, bitterness, astringency, sweetness and flavour tastes considerably decreased with time from 0 to 30 minutes and then slightly decreased. Tannin content also slightly decreased when the extraction time elapsed from 0 to 150 minutes. Catechins content in tea extracts also gradually decreased with time and those contents significantly drop after 120 minutes regardless of tea products. Main catechins in tea extract are epigallocatechin (EGC), epigallocatechin-3-gallate (EGCG), epicatechin gallate (ECG), and gallocatechin gallate (GCG) in all tea products. In tea extracts, sensory quality decreased with progressing elapse time an ambient temperature by decreasing sensory taste, tannin, catechins contents, therefore the best quality was kept when the elapsed time was 0 minute.