So my question is still, given that, at least on the forum, that the pasteurization of certain vendors kits is the reason for the kit taste; Why only kit taste in red kits?
Assuming the pasteurization is the cause of KWT, and if the red and white kits are pasteurized using the same process, one difference is that red and white concentrate are not the same substance. They are produced by very different processes, and it appears (to me) that the heavy constituents in red grape concentrate react poorly to the heat. Without details from WE and the other major kit vendors, I don't expect we'll find a better answer.
An avid reader of Sherlock Holmes as a teenager, the line "When you have eliminated all which is impossible, then whatever remains, however improbable, must be the truth." has been part of my problem solving process since then. Applying that premise to this problem, I find that I cannot eliminate enough things to form a reasonable conclusion.
FWK's process, which does not include Pasteurization and is not shelf stable, eliminates KWT. However, we know of at least 2 other processes: WE's old process and their new one, both of which are shelf stable. The old one can produce KWT, and supposedly the new one doesn't (my limited experience is no KWT).
Unless WE's new process doesn't include pasteurization, we cannot form a conclusion regarding the effects of Pasteurization. I'd like an answer to this, but the facts available to us do not support one.
A quote from Tim Vandergrift:
"If you read between the lines, an awful lot of commercial wine is made exactly like wine kits, with the same raw materials, and the same techniques. That's why I find it consistently funny when anyone says they don't like 'kit' wine—they're usually already drinking it, but paying way more from a commercial source!"
I checked the sites of several concentrate vendors. They pasteurize their concentrate, but recommend refrigeration at 40 F. Since most kits are shelf stable, I suspect a different process is used. There is a huge difference between shelf stable and not, so it appears that Vandergrift's statement is not 100% correct, as there is a difference in the concentrate.