There are many steps to make Japanese green tea.
Harvest, steaming, repeat of rolling and drying, sieving, size sorting, firing, etc.
Especially, flavor of green tea remarkably depends on firing, as well as roasting of coffee. For example, “Oohashiri” and “Hien” produced by Sagara Bussan co. ltd. has a great sweet aroma. Perhaps the luscious aroma would be derived by the special technique of firing of the company.
It is well-known that heating food can provide sweet, roasty, nutty, toasty aroma due to Maillard reaction, for example coffee, sesame, nuts and of course green tea.
There are various aroma compounds produced by amino-carbonyl reaction so-called Maillard reaction. This reaction has been attracting many food scientists due to its multihued reaction pathways changed by heating condition and ingredient constituents.
As for the roasty aroma of green tea, some compounds are considered to contribute the roast flavor, such as furfural, 2-acetylfran, 4-methylfurfural [226], alkylpyrazines [227, 228], etc.
2-acetylfran is considered to contribute not only sweet and roasty aroma,
Surprisingly, one pyrazine (2,3,5-trimethylpyrazine) has an effect to improve blood fluidity[231].
Thermally processing green tea provide additional health benefits!!
In addition to such health benefits, Maillard reaction products could provide good body of tea infusion. For example, 2-acetylfran is considered to give good body to foods [236].
Representative compounds of roasty aroma derived from firing of green tea.
Firing is one of the key processes to determine the flavor of tea, which provides luscious aroma, good body and health benefits for tea. If you smell what green teas are expressin’!
— References —
[226] Hara T., Kubota E. (1970) : Volatile Compounds of Roasted Green Tea Part 1. Carbonyl Compounds, Tea Research Journal, 32:62-66.
[227] Mizuami Y., Sawai Y., Yamaguchi Y. (2008) : Analysis of Key Odorants in Roasted Green Tea, Tea Research Journal, 105:43-46.
[228] Nakada N., Hara T., Isogaya K., Urushibata M. (1988) : Firing Process of Tea by Far-Infrared Radiation, Tea Research Journal 68:14-21.
[231] Suganuma H., Inakuma T., Kikuchi Y. (2002) : Amelioratory Effect of Barley Tea Drinking on Blood Fluidity, Journal of Nutrient Science and Vitaminology 48:165-168.
[236] Hayase F., Takahagi Y., Watanabe H. (2013) : Analysis of Cooked Flavor and Odorants Contributing to the Koku Taste of Seasoning Soy Sauce, Journal of Japanese Society of Food Science and Technology, 60:59-71.