Do you know why Japanese green tea, sencha is usually prepared with lower temperature (around 80degC / 176F) water? Oolong tea and English tea, usually prepared with high temperature water, are often appreciated due to their great aroma. The aroma can be brewed out by using high temperature water. Unfortunately, sencha doesn’t have a rich aroma like Oolong or English tea has, but it has umami or sweetness. That makes the Japanese tea fascinating.
Bitterness (tannin and caffeine) is extracted more when it's brewed over 80degC (176F). Under 60degC (140F), bitterness isn’t infused much and umami (amino acid) can be still extracted relatively. High-grade sencha which has a lot of umami should be prepared around 70degC (158F) water to bring out a great harmony of umami and bitterness. Around 80degC (176F) is good for average sencha. Low-grade sencha which doesn’t have much umami should be brewed around 90degC (194F) water in order to enjoy its aroma and refreshing flavor with the taste of bitterness.
I hope you will try different temperature brewing with your sencha and find out the best flavor for you. The standard brewing time for sencha is about 60 seconds. The substances infuse faster in higher temperature water and slower in lower temperature. So adjust the brewing time according to the temperature of water. Enjoy exploring Japanese tea ☆*:.。. o(≧▽≦)o .。.:*☆