It seems that tart and sour have different meanings for individuals.
It's a difficult situation: For tea for me, tartness is usually a positive factor, a flavor that adds brightness and/or complexity, a perkiness or lightness....For me for tea, sour connotes a taste that is not pleasant, leading a drinker to wonder if something is wrong (perhaps foul or rotten, decayed, etc.).
Words in the English language vary in meaning between the USA & UK & around the world. Then there is the problem of varying situations:
if one bites into a slice of lemon, initial sourness may result in a pleasant, refreshing experience while sucking on that slice for 10 seconds may lead to a sour mouth that one is sure to quickly rinse out.
I guess to be understood, one must add modifiers, such as writing, "a pleasant tartness".
I was recently asked if my aged oolongs were sour. They are not. (Of course, wordy me, wrote much more than that
I started my day by preparing 1160 ml of 1998 to search for tartness.
This aged oolong prepared from leaves from very high altitude were traditionally roasted (very carefully in bamboo baskets rotated about every 20 - 30 minutes for 2 - 3 days). During the 22 years spent in ceramic urns, the tea did not get ruined. Nothing happened to make leaves sour. I do believe that they weakened slightly because my usual ratio, 1 gram of leaves per 50 ml of water, needs to be adjusted. I use 1 gram for 40 ml for this tea most of the time (steeping the leaves 4 times for 30 seconds).
Today I used 1 gram of tea for 30 ml of water. Searching for tartness, I flash-brewed the first 3 infusions. I tasted each separately then put them into a large teapot that I use as a server. The leaves in the hot water for so little time did highlight tartness; yet, there it was not strong, far from being a dominating flavor. 5 - 10 seconds of steeping time (rounds 4 - 7) did downplay tartness. Even just a few more seconds of steeping resulted in a much more interesting, complex cup. (All 7 infusions combined was the best drinking. For the future I plan to do quick steeping (not flash) 1 gram per 30 ml to stack about 7 rounds.)
Drinking this tea in great quantity, I find that the benign taste of the roast (so nicely mellow) can feel more assertive while first putting yet another significant amount of it into mouth. Also, sucking in my cheeks will allow me to identify the tartness that blends into the stacked infusions. Cheers
