pH for hydration?
I've been baking successfully for decades BUT, I just realized that my tap water was pH 9.3. Zowie! Tastes fine. The reason is that our lake water is pH 8.2, but it has moderate mineral content, so they add lime (a common procedure) to make it more alkaline, such that some of the minerals precipitate out. So I was wondering about using highly alkaline water for bread. Would I be better off neutralizing it (which I could do easily with a little lemon juice or vinegar).
What is the optimal pH for hydrating flour for bread, and what are the effects of high alkalinity or acidity? For that matter, how does mineral content of water affect bread baking? I could use distilled water if necessary (my a/c produces gallons of distilled water in the summer!)
I should add that while my pH is high, my water alkalinity isn't that high. So yeast action, which tends to acidify, might not have a lot of trouble acidifying this water.
No guesses, please. I'd like some real experience, or scientific understanding.
Coming at this from a biochemical standpoint. A more acidic dough is generally favorable, for a few reasons. Emily Buehler discusses pH a few times in her very enjoyable book that is recommended on this site: http://www.thefreshloaf.com//bookreviews/breadscience. Mainly she describes how certain enzymes are more active at a lower pH, which helps them chop the gluten-forming proteins into smaller pieces, which can form a better gluten structure more quickly. I don't know how rigorously this idea has been tested (she gives a few older references), but it seems biochemically sound to me.
I would also think that a more acidic dough helps to keep carbon dioxide gas in the dough, leading to better oven spring when it is baked. This is because of the equilibrium between carbon dioxide and bicarbonate, which is shifted towards the former at low pH. When the pH is more acidic, CO2 is more likely to form a gas, which inflates the dough. Something similar happens in the bloodstream, the Bohr effect, which is an important mechanism for delivering oxygen to cells and releasing CO2 in the lungs.
The question of optimal pH is complicated and it's easy to imagine that different doughs would demand more or less acidity, especially depending on the enzyme content of the flour. But the general trend I think holds true, that a lower pH is better for mixing and fermenting dough.
Thank you. Based on what I've managed to find online, this is consistent, and with a better explanation. But it doesn't really answer my question. One gathers that finished dough should be slightly acidic. Maybe pH 5-6. But fermentation acidifies. So the question is whether starting with an alkaline hydrator (in this case water at pH 9.3) fermentation will eventually get you where you want to be. Now, it probably depends on how heavily buffered the liquid is. If heavily buffered, it's going to be harder to acidify.
Maybe the way to answer this question is just to test my finished sponge, after fermentation, and see if it's where it should be.
Using AC water is a foolish idea. If water quality really bothers you, you are better off getting RO equipment. Or buy 1 gallon for under $1 at the supermarket.
I concur about not using AC water. Whatever type of air-conditioner you have, the filtration system is not going to filter out all the contaminants that are in the air. Then there's the fact that any stagnant water left behind is going to have all kinds of nasty things growing in it.
Sorry folks, but that's not correct. A/C condensate is *precisely* distilled water. Very well washed, after years and years of air conditioning (though one adds vinegar every month to the system flush out insects that crawl into the line). Contaminants in the air? Um, what might those be? You mean the contaminants that are raining down on my sponge as it sits in the air?
Now, that being said, condensate might not be free of bacteria (e.g. Legionaries disease), but this stuff is all going to get baked anyway.