At the initial steaming point (aracha), about 6% of the water contents remains in the leaves within 1 week. Due to the water content in the tea, steamed leaves will change to a reddish color and lose their flavor and freshness. Roasting and drying reduce the level of water in tea to around 3% and it is then suitable for preservation. Extreme drying is not good for maintaining tea flavor either.
The quality of the tea depends on the amount of nitrogen contained. It is because tasty components, amino acids and L-theanine, are composed of nitrogen. Ichibancha (first-picked tea) has more nitrogen than Nibancha (second-picked tea) and a soft tea that has a lot of new buds has higher nitrogen levels. Ichibancha has a nitrogen level of roughly 5%, while Nibancha contains almost 4% nitrogen.
Amino acid (%)
Green tea's sweetness comes from amino acids. Ichibancha (first-picked tea) has high levels of amino acids while Nibancha (second-picked tea) has less. The higher the amino acid level is the higher the quality of tea. Ichibancha contains roughly 2-3% of amino acid and Nibancha has only about 1-2% of amino acid.
Green tea's sweetness also comes from theanine. Like amino acids, Ichibancha (first-picked tea) has more theanine than Nibancha (second-picked tea). The higher the theanine level is the higher the quality of tea. Ichibancha has roughly 1-2%, while Nibancha contains less than 1% of tannin.
Vitamin C (%)
Tea leaves that absorbed more sunlight have more vitamin C. This changes annually based on the weather, when there were many sunny days during the picking time the tea has high levels of vitamin C, when there were many rainy and cloudy days during the picking period the tea has less vitamin C. Vitamin C changes the aftertaste of tea. A lot of vitamin C leaves tea with fresh aroma aftertaste, with little vitamin C, there is bad aftertaste. Both Ichibancha (first-picked tea) and Nibancha (second-picked tea) should contain more than 0.4% of vitamin C for fresh aftertaste. When not stored correctly the vitamin C content can drop to as low as 0.2%, so you can use this number as a guide line for storage.
Green tea's bitterness comes from caffeine. Higher quality tea has more caffeine in it and 2-3% is the normal amount. The lower the grade, the lower the level of caffeine.
It is a bitter nutrient, also called catechins. Bitterness in tea is usually taken as bad tea but bitterness is actually one of the positive tastes, from our experience. The tastiness of green tea does not only come from amino acid and theanine. Bitterness also adds to depth of taste. The profound tastes of tea: sweetness, good aftertaste and bitterness that brings out the depth of taste blends into green tea's thick flavor. Ichibancha (first-picked tea) contains roughly 12-13% of tannin and Nibancha (second-picked tea) about 14-15%. The lower the grade of the tea, the lower the tannin content.
Usually the less fiber there is in tea the higher quality the tea is. With apples, the taste is much better if the fruit is harvested after ripening rather than harvesting early and letting the apple ripen off the tree. The same can be said of green tea. Instead of early young tea leaves, green tea harvested in mid-season is better.
The highest quality tea has 17-18%, good grades have 19-20%, middle grades have 21-22% and normal grades 23-24% of fiber. Gyokuro has as low as 15-16% of fiber. Well balanced tea is always good cup after cup.
The difference between 1st-picked and 2nd-picked teas
Ichibancha (first-picked tea) has a lot of amino acids, L-theanine and nitrogen along with vitamin C and may be superior to Nibancha (second-picked tea). However, Nibancha surpasses Ichibancha in terms of the amount of catechins. Also in some good harvest years, Nibancha may still have soft tea leaves that are usually in Ichibancha. You may be able to get high quality Nibancha very economically. Please try both. We can almost hear people's conversations, saying "I am a fan of Ichibancha" , or "I am a fan of Nibancha."