The search was fruitless...and I realized at the end of it that I hadn't considered something very important. With the dilution that is generally recommended, it is extremely unlikely that the pH of the water is affected much, if at all. I have hard water. It is really, really difficult to overcome the natural buffers in the water to bring it from an alkaline pH to a neutral pH--I know this because getting the water adjusted to fill a new fish tank is a bear.
Actually, adding ACV to hard water would make a bit of the water's calcium carbonate more biologically available as calcium acetate. Ditto for magnesium.
So, since fat isn't digested and absorbed until it hits the small intestine, it makes sense that the fatty acids referenced in my previous post WOULD have an effect on intestinal pH and therefore calcium metabolism, but is also why this reasoning cannot be transferred to ACV.
I love science. Could you tell?