On beans and hard water

On the heels of the cassoulet I made a couple of weeks ago, I’ve continued working with dried beans, trying to get a handle on the best way to cook them. It seems I’m not the only one who has dried beans on the brain. At this point in the winter, many storage vegetables are starting to be past their prime, and spring vegetables won’t be coming up for a while yet, but dried ingredients like beans have the benefit of being seasonal and delicious.

These Mexican black beans, made using a modified Rick Bayless recipe, were my most successful bean dish so far this winter. I started by soaking them overnight in tap water, then drained and rinsed them before cooking them in demineralized water with a chopped onion and a dollop of lard for about two hours. The end result was beans that held their shape but were tender throughout, not the least bit mealy or crunchy. Served over rice with a little sour cream and some pickled jalapeños, they made for a thoroughly satisfying meal. And as a bonus, I have leftovers that I can turn into refried beans.

In his post, Ruhlman notes that Modernist Cuisine suggests cooking beans in deionized water, which doesn’t taste very good on its own, and raises the question of why you’d cook with something that doesn’t taste good. Water is a funny ingredient: the things that make it taste “good” are the dissolved minerals that make cooking processes – like dried beans – such a headache for me. (That’s why Nestle bottles water at its plant in Aberfoyle, just south of my home in Guelph: because all those minerals make for delicious water.) To alleviate those headaches, you have to minimize the chemical interference from the minerals, and deionized water is a good way to do so.

In this case, counterintuitive as it may seem, cooking with an ingredient that doesn’t taste good on its own ultimately leads to a better final product, because the substances that makes that ingredient taste good are directly at odds with the characteristics that make for a good result. Certainly I’ve never found dishes cooked with deionized water to be less than flavourful; the ingredients I add myself, whether beans or kombu and bonito flakes, add more than enough flavour. For that matter, deionized water doesn’t taste exactly bad; it just tastes flat.

Of course, if your local tap water is soft anyway, then there’s no need to incur the environmental cost of cooking with bottled water. For me, though, the best results for beans seem to come from cooking them in demineralized water, and I’ll continue to cook them that way… at least until my pressure cooker arrives, and I can try out the Ideas in Food method!

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3 Responses to “On beans and hard water”

  1. Tap water may be ‘hard’ from an excess of calcium and magnesium salts. These bind to the bean proteins and prevent them from taking up water. The metal ions in tap water bind to bean albuminoids slowly at room temperature but quickly at cooking temperatures, so it makes sense to soak in tap water but cook in de-ionized water.

  2. Matthew Kayahara March 18, 2011 at 1:42 pm

    Thanks, salvarsan, it’s good to have another opinion that agrees with what I did!

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