Improvement of the Bitterness and Astringency of Green Tea by Sub-Critical Water Extraction

Green tea is known for its high content of functional catechins and is commonly consumed for its health-promoting effects. However, green tea catechins are highly bitter and astringent, and thus the development of products that can be consumed regularly is necessary for their efficient, routine intake. The aim of this study was to use sub-critical water extraction (SWE) to produce a green tea extract both less bitter and less astringent than typical green tea. Results from chemical evaluation using a taste sensor analyzer indicated that SWE reduced bitterness, astringency and unpleasant taste while it retained the original fragrance in the green tea extract. Furthermore, the SWE-produced extract had higher amounts of arginine and water-soluble pectin, which are thought to mask the bitterness and astringency of green tea.