So You Like Flavor? Don't Soak Your Black Beans!

The Food Lab

Unraveling the mysteries of home cooking through science.

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Have you been soaking your black beans all along? Surprise! They're better when you don't. [First photograph: Vicky Wasik, other photographs: J. Kenji López-Alt

Earlier this year I published a quick and easy recipe for Black Bean Soup with Chorizo and Braised Chicken. It was a variation on the same basic black bean soup that I make at least a half dozen times a year: soak some black beans in water overnight, sweat some aromatics, add the beans and broth, cook it all until the beans are tender, then purée half of it to thicken it up.

Who can argue with something that simple and delicious, right?

Turns out there's one man who had a bean to pick with me. Not hours after that recipe went up, I received an email from Russ Parsons of the L.A. Times.

Here's what he had to say:

Black beans cook so quickly soaking only saves 30 minutes or so. It also marginally helps keep them whole, but you're going to be pureeing some anyway. and the flavor is so much better. Just sayin

When Russ writes, I listen. After all, his fantastic book How to Read a French Fry was one of the reasons I got into food science and writing to begin with.

He even wrote an article about it way back in 1994. Could it be true? Have I really been soaking black beans in vain all these years? Armed with Max's Lazy Cook's Black Beans recipe and a few pounds of dried beans, I hit the kitchen to find out.

The Test

To test the theory, I cooked three identical batches of those black beans. The first I soaked in water overnight, then cooked them in the same water I'd soaked them in. The second I soaked, drained, rinsed, then cooked in fresh water. The third I cooked directly in the pot from their dry state, no soaking whatsoever. In each case, I cooked the beans until they were completely creamy and tender and the liquid reduced down to a rich sauce. Here's what I found.

The Results

Ease of Preparation

There's a clear winner here: to cook the non-soaked beans, all you have to do is add water and go. They softened up in less than an hour and a half—a mere 20 minutes longer than the soaked beans' 1 hour cook time. And it meant that I didn't have to worry about remembering to soak them the night before.

Winner: Un-soaked beans.

Color

One difference is immediately noticeable, even before putting the beans in your mouth:

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While the beans cooked straight from dry are dark black, the soaked and rinsed beans come out much paler in comparison. This makes sense—When you dump out the soaking liquid, you can see that it's absorbed plenty of dark pigments from the beans. The beans cooked in the same liquid they were soaked in come out just as dark as the un-soaked beans.

I don't know about you, but I like my black beans to actually be black.

Winner: I'm going to call a tie for un-soaked and cooked-in-soaking-water beans in this category.

Flavor

Here's where things actually get interesting. In every case, the soaked-and-rinsed beans were the least flavorful. They just didn't taste as beany. Between the un-soaked and the cooked-in-soaking-water, it ended up coming down to exact process. When cooking the beans plain with just water and salt, they both ended up tasting pretty much identical.

However, when I introduced aromatics to the mix—like the orange and onion used in Max's recipe—the differences became clear: with their shorter cook time, soaked beans simply absorb less flavor from the aromatics. The un-soaked beans had a distinctly stronger orange and onion aroma to them, which to me is a desirable trait—I'm adding those aromatics for a reason, right? Might as well maximize them.

Winner: Un-soaked beans.

Texture

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For this test, I measured out 50 grams of each batch of cooked beans and counted the ratio of intact beans to broken or blown-out beans. I was genuinely surprised to find that in all cases, the beans came out just about the same—the soaked beans blew out about 15% of the time, while the number of busted un-soaked beans came in a couple of percentage points higher.

I know that with firmer beans like cannellini or kidney, soaking can mean the difference between a pot full of blow-out bean fragments and a pot full of perfect smooth-skinned beauties. But with quick-cooking thin-skinned black beans, it seems that the difference is very minor indeed.

More to the point: the batch of beans made by soaking and rinsing had a markedly thinner gravy, which makes sense, given that a lot of the material you tip down the drain with the soaking water is starch released by the beans as they soak. If you, like me, like your beans rich and creamy, you want that excess starch in there.

Winner: A tie for un-soaked and cooked-in-soaking-water beans in this category.

Digestibility

"Kenji," my wife said last weekend as we drove home from the Alameda Antiques Faire, her face blocked from my view by the oversized 1960's Danish teak-wood floor lamp we'd just scored, "did you just fart?"

Nope.

"Are you sure?"

Yup.

Normally I'm the kind of guy who'd readily come clean about the comings and goings of my gastrointestinal system, particularly with my wife: being married to someone who eats for a living gets you used to that.* But this time, in the name of science, I was forced to deny it.

*Normally I'm also the kind of guy who shies away from scatological humor and fart jokes, but, well, this time there's actually some relevance to the article at hand.

A Mighty Wind

You see, conventional wisdom states that un-soaked beans are far more difficult to digest than soaked beans. I wanted to track exactly how big these differences were. I started my testing with animal trials. Over the course of four days, I fed Hambone, my ever-eager shar pei (or should I say guinea pig) a few tablespoons of black beans mixed in with his normal food, alternating with soaked vs. un-soaked beans each day. (I didn't dare feed any to our Boston terrier Yuba, who could probably propel herself into orbit were she given any extra assistance.)

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Did I do that?

Turns out that tracking dog farts accurately without specialized equipment is actually quite difficult unless you're willing to get even more down and dirty than I am in the name of good ol' gonzo journalism. Perhaps Apple will come out with an app for that. In the meantime, I decided that the only way to track this for certain was for me to bite the bullet (or bite the bean) and move on to the human trials. And as my wife is physically incapable of passing gas (at least, so she claims), that left me to do the dirty work.

So why keep the testing a secret from my wife? Well, the thing about flatulence is that it not only affects the flatulent, but it also affects the flatulated-at. I had no trouble tracking my own stats, but I also wanted to see whether or not there'd be an appreciable difference in how those around me perceived my troubled gut in a real world setting. In other words, I didn't want my wife to be on the look out. If she noticed, she noticed. If not, she didn't.

Well, she noticed. I had indeed eaten the un-soaked black beans that morning before we left for the flea market, and a few hours later, they'd worked their musical magic.

That said, in all honesty, even keeping careful track myself, the differences I noticed were very very slight at most. Enough that it could be chalked up to random chance without the benefit of multiple testing subjects and the next generation iProduct to track things with. In no case did I feel uncomfortable after eating the beans.

Winner: Three way tie.

To Soak or Not to Soak?

So what's the conclusion? Well it seems obvious: don't bother soaking your black beans. Un-soaked beans taste better, cook almost as quickly, have great texture, and don't cause significantly worse problems for the digestive system. Of course, this applies only to black beans as far as I know—perhaps there are some other thin-skinned beans around (black-eyed peas and baby lima beans come to mind) that would benefit from a similar method, but I've yet to test it.

And if you'll excuse me, I'm now off to read some Russian literature just to kick the negative karma of fart jokes out of my system like too much passed gas.