pH and Cooking
March 2, 2011 2:52 PM   Subscribe

What is the effect of pH in cooking?

From reading and experimentation, I've gathered that: I'm a little confused, though--acid can break down food or hold it together. Are there some resources that definitively explain the effect of pH at various stages of cooking/eating, the interaction of pH and heat, etc?
posted by domnit to Food & Drink (9 answers total) 11 users marked this as a favorite
On Food and Cooking by Harold McGee! Great book on science and history of cooking. Definitive!
posted by mollymayhem at 3:04 PM on March 2, 2011 [4 favorites]

There are no resources that definitively explain the effect of pH at various stages of cooking/eating. This is a little like asking how chemistry effects cooking and eating, there are way to many variables for a simple answer to this question.

Here is an article that speaks a little to the potential complexities

Excerpt: This kind of chemistry happens when you put chopped red cabbage into a hot pan. Heat breaks down the red anthocyanine pigment, changing it from an acid to alkaline and causing the color change. Add some vinegar to increase the acidity, and the cabbage is red again. Baking soda will change it back to blue.
posted by pseudonick at 3:06 PM on March 2, 2011

Extreme pH, high or low, will tend to denature proteins, which is why fish appears cooked after soaking in lime juice. This explains the poached egg whites, too.

Related to the slowing of pectin's breakdown, Shirley Corriher says that starch granules don't swell and soften in acidic conditions, which means that you can cook rice or potatoes for a long time and they will still be hard. It had happened to me and I never figured out what was going on until I read about it. You'll probably want to read her book Cookwise, in addition to Harold McGee's On Food And Cooking.
posted by Ery at 3:06 PM on March 2, 2011

I second the Harold McGee suggestion. Addall found it for $18 including shipping.
posted by MansRiot at 3:09 PM on March 2, 2011

Response by poster: I've been eying On Food and Cooking, so it's probably time to pick up a copy. Does the section "Water and Acidity: The pH Scale" from Chapter 15 address my questions?
posted by domnit at 3:24 PM on March 2, 2011

Nope, that section is actually pretty tiny. Info on acids and bases is scattered throughout the book, because they play strikingly different roles in different situations.
posted by soma lkzx at 3:40 PM on March 2, 2011

Great little article from a google search. Its been a while since chemistry, but I'll translate what they're saying into cooking terms.

So, when you apply an acid to to a meat, a few things occur. First and foremost, you denature the protiens, forcing them to precipitate - effectively pulling out the water content, and rendering the remaining protein structure straighter and, for the lack of a better word - firmer. This can be used to chemically cook meet, as in ceviche. You can also cook an egg this way - hence there being so much care when making a holandaise sauce.

The same thing applies to bases being inserted into baking, once again you are forcing water and salt to alter their bonding habits - you are breaking down the water, forcing the release of gasses, and effectively cooking yourself a new lattice. Add too much of a base, and you won't have enough water and salt to use it up - your food will get... dry as the chemical reaction is then allowed to take place in your mouth instead.
posted by Nanukthedog at 4:20 PM on March 2, 2011

Acids and bases don't have stock effects, rather, each "thing" in food is affected different ways. There is no easy rule.

And different acids/bases will have different effects. Very basically, what makes an acid an acid is that when it is put into water, its molecules separate. You get the ions which create the Ph effect, but then you have the other ion in there doing other things. So citric acid and lactic acid might create the necessary ph, but the other half of the molecule does wildly different things.
posted by gjc at 4:27 PM on March 2, 2011

Acid makes curds form in milk, and is used extensively in cheesemaking.
posted by Leta at 5:13 PM on March 2, 2011

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