teasecret wrote: ↑
Tue Jan 29, 2019 9:35 am
I'm working on some experiments that I'll put in a blog post in about a week. This stuff takes time!
In the meantime, what exactly is alkalinity and its relationship to the resulting tea?
pH is how we describe the ratio of protons and hydroxyl ions in water due to the self ionization of H20 into H+ and HO-
low pH means this equilibrium is shifted to H+ side and there are lots of H+ protons and the water is acidic. In acidic conditions, compounds in the water tend to be in their protonated form like -COOH versus their unprotonated form COO-. This has really big affects on what form minerals and tea compounds take and their solubilities and probably their properties such as taste and smell.
From how I understand it, alkalinity is related to the pH, but it refers to the actual amount of basic compounds in the water. If there are 6 grams per liter of bicarbonate, this is different that having only 3 grams of bicarbonate per liter, even though the pH might be the same. Alkalinity is important to water chemistry because it dictates how well the system buffers change. If there is a lot of bicarb, you will have to add a lot of acid to lower the pH. If there is a low alkalinity, then small additions of acid can cause a big change in pH.
I really don't know how these two affect tea, though. This is why I like what Victoria is doing. If we get lots of data on the types of waters that make tea taste good, then we might be able to figure out the important parameters.
It seems that a little bit higher pH is preferable. I feel like this helps give a thicker mouthful.
I would guess that you want a high enough alkalinity so that the pH is maintained throughout the addition of tea compounds to the water, but not too high that it effects extraction of key components.
Steeping tea is an incredibly complex process. There are so many different compounds in the leaf, some of them good and some of them detrimental to the flavor/aroma. It's a chemists nightmare to perform such separations with a single process. I can't fathom trying to claim a high pH extracts more x compounds while alkalinty does y.