What's the Best Way to Cook Whole Grains? Our Tests Show It's Not What You Think.

When I first started working at Serious Eats, I wrote an article that explored the effects of pre-soaking grains on their taste, texture, and cooking time. What I found was that soaking did very little to improve the grains, and I concluded that skipping the pre-soak was generally the way to go. Then I closed with a line that, at the time, seemed like a given.

"I, for one, will just accept my grains as they are and wait patiently for them to do their thing. That, or I'll reach for something I know will work: my pressure cooker."

It seemed obvious enough: Of course a pressure cooker would be the best way to cook grains. I mean, I love my pressure cooker and the magic it routinely performs. It cooks beans faster, stocks faster, tough cuts of meat faster, and—one of my favorite tricks—octopus, which becomes tender in no time. Why wouldn't it work just as well with grains?

But as soon as the article was live on the site, I started to wonder if it was really true. The question gnawed at me—what if I had cavalierly stated something as fact and been totally wrong about it?

The Test

I knew I had to put my statement to the test. To do it, I cooked both whole (bran-on) and pearled/polished (bran largely removed) grains* in regular boiling water and a pressure cooker, then compared the results. The grains I used were polished (pearled) farro, whole-grain spelt, whole-grain rye, and whole-grain wheatberries. And to be doubly thorough, I did some batches with grains that had been pre-soaked (just in case that made some sort of difference where the pressure cooker was concerned), and others with grains that I cooked straight from dry. I also tested using two different pressure cookers, to account for possible differences in cooker types: my own Kunh Rikon stovetop model, and the SE test kitchen's Breville electric pressure cooker.

Before going into detail on the results, a quick note on how pressure cookers work, and how I used them in these tests. Pressure cookers trap steam inside the vessel; as the trapped steam builds up, the pressure inside the cooker increases. Because the boiling point of water is tied to atmospheric pressure, increasing the pressure in the cooker results in higher temperatures (water boils at 212°F at sea level, defined as approximately 1 bar atmospheric pressure; inside a pressure cooker, the water's temperature can go up to around 250°F, depending on the cooker and its pressure settings).

As a matter of practice, cooking times for pressure cookers start once the cooker is fully pressurized, and do not include the pre-heating phase. Once cooking is complete, there are three ways to depressurize a cooker, which otherwise can't and shouldn't be opened—unless taking a bath in an explosion of steam sounds like a good idea to you.

• The first is to press the cooker's steam-release valve, which vents the steam trapped inside the cooker, dropping the pressure to the point where the lid can be opened.
• The second is to run the cooker under cool water, which cools the cooker, condensing the steam inside; as the steam condenses, the pressure drops (this method should not be used on electric cookers).
• The last is to let the cooker cool down on its own, until the pressure has dropped enough to open the lid; this is not an ideal method for foods that can overcook as they sit inside the cooker.

For my tests, I used both the steam-release valve and the tap-water method, for quickest pressure release.

The Results

Before going into detail, I'm just going to get this out of the way: I hereby retract the closing line of my earlier piece, because I no longer think that pressure cookers do much for cooking grains.

Let's take a closer look.

Pre-Soaked Grain Tests

Even though I'd already determined that pre-soaking isn't necessary for cooking most grains, I decided to include pre-soaking in my tests here, just in case it ended up being an important factor in pressure cooking.

The first soaked grain I cooked was polished farro. Right off the bat, this test exposed one of the biggest risks of pressure cooking grains: because a pressure cooker is a sealed vessel, you can't see the food inside the pot while it's cooking.

For a relatively quick-cooking grain like polished farro, that can be a risky thing. In regular boiling water, the farro became tender in about 20 minutes, and it was easy to monitor its progress in the pot.

With a pressure cooker, it took about 10 minutes for the cooker to become pressurized, and I then let the farro cook for 5 minutes once pressure had been reached. I depressurized the cooker with the steam-release valve, and wasn't happy with what I found inside: blown-out, overcooked farro grains.

Of course an even shorter cooking time could have prevented this, but it underscores the risk of overcooking some foods in a pressure cooker. Based on this test, quick-cooking pearled grains are better off just being boiled: your time savings are marginal in a pressure cooker anyway once you factor in the preheating and depressurization times, and the inability to see the grains means a much higher chance of letting them go too far.

Next up, I cooked soaked whole-grain spelt. Here, I have to admit that I ended up letting this spelt soak for three days before testing it, because, well, life happens. That actually proved to be interesting: soaking grains overnight (about 8 hours) may not make much difference, but soaking grains for 3 days does change cooking times. With such a lengthy pre-soak, the boiled spelt took about 25 minutes to cook. In the pressure cooker, I let it go for 10 minutes, not including the preheating time of about 10 minutes, plus depressurization time. Altogether, it was in the pressure cooker for a little over 20 minutes.

As you can see in the photo, the starchy contents of the grain wanted to blow out in both instances, possibly the result of being super-hydrated after such a long pre-soak. Luckily, the bran held it all together and maintained its pleasant, chewy texture, proving that it's incredibly hard to overcook whole grains. Still, the two samples were indistinguishable from each other. (For the record, I don't think 3 days of pre-soaking is worth the reduction in cooking time.)

Once again, the pressure cooker wasn't demonstrating much of an advantage, though at least with bran-on whole grains like spelt, the risk of over-cooked, blown-out grains is much less of an issue.

No-Soak Grain Tests

So far, the pressure cooker wasn't impressing me. But maybe the pre-soaking was leveling the playing field. Maybe grains cooked from dry would do better in the pressure cooker.

So for my next tests, I tried both dry whole-grain spelt and wheatberries.

Here, the boiled spelt cooked in about 40 minutes. And once again, the pressure cooker was done just a hair faster, about 35 minutes including pre-heating and depressurization. Out of the pot, I struggled to find a difference between the two. In the photo above, you can see that the boiled spelt at left looks slightly drier than the pressure-cooked spelt, but as I tasted them side-by-side, I couldn't discern much of a difference. I decided to switch to my macro lens for a closer look at the grains.

As I zoomed in, I had a harder and harder time distinguishing between the two. While the piles of grain had initially looked a bit different, up close they looked basically the same. Then I realized that I had drained the boiled spelt first, allowing it more time to air-dry; as the pressure-cooker spelt sat out, it started looking more and more like the boiled spelt.

As for the wheatberries, they performed just about the same, in their case 50 minutes for the boiled batch, and 40 minutes for the pressure cooker. Rye grains, too, produced similar results.

Conclusion

In all cases, the pressure cooker was slightly faster than a pot of regular boiling water, but to my surprise, the differences were small—about 10 minutes in most cases. The grains themselves were indistinguishable from each other, regardless of how they were cooked, except for the pearled farro, which overcooked in the pressure cooker. Given these results, I'm afraid to say the pressure cooker doesn't have a drastic impact on the cooking time or taste and texture of grains, and, in the case of polished/pearled grains, has a greater risk of ruining them.

One of the most misleading things is the time given for pressure cookers: While it makes sense to only start the clock once the cooker has become pressurized (since different cookers and quantities of food inside will have different heat-up times), it hides the true cooking time, which includes the heating up and depressurization times. For grains, that ends up erasing much of the apparent time-saving benefits.

I'll still use my pressure cooker to cook whole, bran-on grains, because it doesn't do any harm at all, but I'll do it knowing the reality, which is that I'm actually reaching for a tool that, at least for this task, doesn't actually work much better than a regular old pot of water.