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The Science of Beans

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Beans play an important part in American culture and especially barbecue culture. Hard to find a pit stop that doesn’t serve some sort of beans.

Dried beans are much cheaper. Canned beans are quicker, easier, and safer. 

Open the can, drain the salty liquid, rinse, heat for 30 to 60 minutes, and canned beans are ready to eat. They are also safer. I’ll discuss this below.

Once upon a time I felt it was a philosophical requirement for me to cook only dried beans. I now prefer canned.

Dried beans are cheaper and some folks like the taste better, but they take a lot of time, and there is a minor health risk.

You can find dried beans in any grocery, and a large selection in Mexican groceries. You can find hierloom and unusual varieties online. Try those grown by Steve Sando of Rancho Gordo.

Raw or dried beans, especially red kidney beans, must be handled properly. They might have a naturally toxic protein called Phytohaemagglutin (a.k.a. kidney bean lectin). It is present in many plants and animals in small quantities, but kidney beans and a few others might have a lot of this compound. Proper cooking denatures the protein and destroys the toxins. Research suggests the best method below is the safest. It is infinitely preferable to vomiting, diarrhea, and severe abdominal pain for 3 to 4 hours, all of which can be triggered by as few as 4 to 5 beans that have not been prepped properly.

To do this right, you should start the soaking process at least 24 hours before serving time.

  1. Dump dried beans on the counter and make sure there are no pebbles or other foreign matter mixed in.
  2. Give them a quick rinse in cold water.
  3. Measure the volume of beans. Calculate three times the volume of the beans and add that much water to a bowl or pot. Add 1 tablespoon of salt per quart of water. Older books say not to salt the beans, but modern cooks have busted that myth. Add the beans and soak at least five hours. You can soak them up to 12 hours if you wish, and you should. It takes a loooonnnnnggg time for them to absorb liquid. The longer that dried beans soak, the less time they need to cook.
  4. Drain the beans and discard the soaking liquid. I know a lot of beanbrains say to save the liquid, but it can be laden with lectin. Play it safe and throw out the soaking liquid. Cover them again with at least 1″ more water than the level of the beans and bring to a boil for 30 minutes. Use a deep pot because once they start to boil they make a lot of foam. Stir occasionally to make sure they don’t stick to the bottom. After 30 minutes, discard the water. The beans can then be added to a recipe and cooked in the recipe. But they will not cook as quickly as canned beans.
  5. After the beans have been added to the recipe let them simmer until they get soft enough to pierce easily with a fork. At first they will rattle around like marbles and when you get experienced you can gtell a lot just by stirring them. Try chewing some as a test. They may need up to 12 hours of simmering. Exact cooking time will vary depending on the type of bean, their size, their freshness, how long they soaked, and how long they boiled. Cooking time will also depend on the cooking method. Beans cook faster in a pot on the stovetop than in a pot in the oven, and longer still on a smoker underneath the meat at 225°F.

If you live at altitude, bean cookery can be concerning. Water boils at a lower temp at altitude because the column of air pressing down on the water surface is shorter and that lowers the air pressure, so vapor escapes the water at a lower temp. As a result it takes longer to cook beans at altitude. A rule of thumb is add 10% for each 1,000 feet above sea level.

The bottom line for dried beans is this: If you prefer to use them, then be patient. Give them plenty of soaking time. Buy the same type and brand of beans several times, and make note of the optimum soak and cook times for you. Once you get the hang of things, they’re easy, and safe.

Pressure cooking option 

Dried beans cook much faster in a pressure cooker. Rinse, soak, boil, and cook 20 minutes in the pressure cooker. Then open the lid and cook another 20 minutes or more until they bean soup is the right consistency.

Click here for Meathead’s classic beans recipes.

Here’s the great Steve Sando of Rancho Gordo, my source for all things beany, with a simple bean recipe. Click here for Meathead’s classic beans recipes.

Approximate equivalents

Here are some useful measurements. They can vary significantly depending on the type of beans, the size of the beans, or the brand of the canner.

  • Dried beans absorb liquid when cooked so increase the liquid in the recipe when you cook with dried beans.
  • Dried beans expand to about 2.5 times their original volume when soaked and 3.5 times their original volume when cooked.
  • 1 can of beans = 15 ounces undrained = about 10 ounces drained = 1/4 pound dried beans.
  • 1 pound dried beans = about 2 cups dried beans = about 5 cups soaked beans = about 7 cups cooked beans = 4 cans drained beans.

A smashing good trick

If the beans are done and it is dinner time and the liquid is too runny, you can put the beans in a pot and boil them, lid off, to reduce the liquid, or you can thicken things by smashing a few beans with a potato masher or by pressing them against the side of the pot.

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Published On: 2/28/2012 Last Modified: 2/13/2024

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  • Meathead, Founder And BBQ Hall of Famer - Founder and publisher of, Meathead is known as the site's Hedonism Evangelist and BBQ Whisperer. He is also the author of the New York Times Best Seller "Meathead, The Science of Great Barbecue and Grilling", and is a BBQ Hall Of Fame inductee.


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