Soaking beans overnight is a habit, not a requirement. Unsoaked beans cook perfectly well; they simply take longer. And lentils, which get swept into the same advice, never need soaking at all.
That said, soaking is not pointless, and the honest version of this article explains what it does before telling you to stop doing it.
One exception first, because it is a safety rule and not a matter of taste. Everything relaxed in this article about soaking, keeping the soaking water and cooking at a gentle simmer does not apply to one species: Phaseolus vulgaris — red kidney beans, white kidney beans (cannellini is the white kidney bean), black beans, pinto beans and their relatives. The FDA's procedure for those beans has three steps, not one: soak them for at least five hours, pour the soaking water away, and boil them in fresh water for at least thirty minutes. That is the whole rule. It is set out again, with its source, under "The one real safety rule" below, and you should read that section before you cook any of them.
What soaking actually does
- It shortens the cooking time, typically by a quarter to a third. That is the main thing.
- It makes cooking more even, because the beans start hydrated all the way through rather than from the outside in. This shows up as fewer beans that are split on the outside and chalky in the middle.
- It lets you discard the soaking water, which some cooks do and some do not. For beans outside the kidney-bean species there is no culinary reason to — you lose a little flavour and colour, and nothing is gained. For Phaseolus vulgaris — kidney beans red or white, cannellini, black, pinto — it is not a culinary question at all: the FDA's consumer procedure is to soak, pour the soaking water away, and boil in fresh water. There the water goes, and the flavour goes with it. See the safety rule below.
- It does not make old beans young. This is the limit worth knowing. Age is the single biggest variable in whether beans soften, and no amount of soaking fixes a bean that has been in a warehouse for three years.
The unsoaked timings
Straight from dry, with the lid mostly on. Lentils, split peas, black-eyed peas and chickpeas can go at a gentle simmer from start to finish. The Phaseolus vulgaris beans — kidney, cannellini, black, pinto — are deliberately not timed in this list: they are the one case where soaking is not optional, so there is no honest from-dry time to give for them.
- Lentils, red or yellow: fifteen to twenty-five minutes. They collapse; that is the point.
- Lentils, brown or green: twenty-five to forty minutes, holding their shape.
- Lentils, French or Puy style: thirty to forty minutes, firm.
- Split peas: forty-five minutes to an hour and a quarter.
- Black-eyed peas: forty-five minutes to an hour, and the fastest of the true beans.
- Kidney beans (red or white — cannellini is the white kidney bean), black beans, pinto: no from-dry timing. This is the one place where this article reverses itself. The FDA's procedure for these beans is to soak them for at least five hours, pour the soaking water away, and boil them in fresh water for at least thirty minutes — all three steps — and we found no authority testing one of them cooked from dry, so we are not going to print a from-dry time. Read "The one real safety rule" below before you start.
- Chickpeas: two to three hours, and the most variable of the lot.
In a pressure cooker, cut all of the bean times to roughly a third and check early, because pressure cookers overshoot into mush without warning. A pressure cooker at pressure runs hotter than a rolling boil, so it satisfies the heat step of the kidney-bean rule rather than conflicting with it — but it does not stand in for the soak and the change of water, which come first. It is a slow cooker, which runs well below boiling, that must never be used for these beans.
Salt early. Acid late.
Two pieces of received wisdom, one wrong and one right.
Salt the water from the start. The old advice that salt toughens bean skins does not hold up in practice — beans salted from the beginning are seasoned all the way through rather than just on the outside, and they cook at least as well. Salt the cooking water like you would salt pasta water: noticeably, but not aggressively.
Add acid at the end. This one is real. Tomatoes, vinegar, wine, lemon and molasses genuinely slow the softening of beans, sometimes dramatically. A pot of beans simmered in tomato from the start can stay firm for hours. Cook the beans until they are tender, then add the acid and cook on. This is the single most common reason a pot of beans "will not cook".
Other things that matter more than soaking
- Age. Buy beans that turn over. Old beans may never fully soften no matter what you do, and there is no visible tell — which is a real argument for buying by weight from stock that moves rather than from a package with no packing date on it.
- Hard water. Very hard water slows softening. A small pinch of baking soda — an eighth of a teaspoon per pot, no more — counteracts it. Too much and the beans turn slippery and taste soapy.
- Heat. A hard boil breaks skins and makes beans split, so a bare simmer, barely moving, gives the most whole beans. That is a texture preference and it does not override the safety rule below: kidney, cannellini, black and pinto beans are soaked, drained, and then given their thirty-minute rolling boil in fresh water first, and some split skins are the price of it. After that half hour, simmer as gently as you like.
- The cooking liquid. Keep it. Bean broth is genuinely good and it is most of what makes a pot of beans taste like something rather than like beans in water.
What to put in the pot
Beans want very little and reward it. An onion halved, a few cloves of garlic, a bay leaf or two, a sprig of thyme, a dried chili, a strip of citrus peel. For a Mexican-leaning pot, cumin and Mexican oregano. For a Mediterranean one, oregano, garlic and olive oil. Whole spices are better here than ground, because they can be lifted out, and because two hours of simmering flattens ground spice into mud.
Save the ground spices, fresh herbs, acid and good oil for the end.
The one real safety rule: kidney beans, and what counts as one
This is the exception to everything relaxed about bean cooking, and it is worth being precise about because the failure mode is genuinely unpleasant.
Raw and undercooked kidney beans contain a lectin, phytohaemagglutinin. According to the FDA's Bad Bug Book, the lectin is found in many species of beans and is present at the highest concentration in red kidney beans, Phaseolus vulgaris. White kidney beans, which the FDA describes as another variety of the same species, contain about one third the amount of the red variety; broad beans, Vicia faba, contain five to ten per cent. As few as four or five raw beans can trigger symptoms, which begin with extreme nausea and vomiting within one to three hours.
Cannellini is the white kidney bean. So is anything sold as a white kidney bean, and so, in practice, is the large white bean in a tin labelled cannellini. It is not a different bean from the one this rule is about; by the FDA's own figure it carries about a third the lectin of the red variety, which is a reduction and not an exemption. Black beans and pinto beans are the same species again. The FDA publishes figures for red kidney, white kidney and broad beans only, and says the lectin occurs in many species of beans — so nobody has published a number that would let us call black or pinto beans safe at a simmer, and we are not going to imply one. Treat every Phaseolus vulgaris bean the same way.
The FDA's procedure, in full
This is the only consumer procedure the Bad Bug Book gives, and it has three steps, not one:
- Soak the beans for at least five hours.
- Pour the soaking water away.
- Boil them in fresh water for at least thirty minutes.
Thirty minutes of rolling boil is the instruction, not a preference. Bender and Reaidi found that boiling for ten minutes at 100°C completely destroyed the toxin, and the FDA cites them — but the FDA then tells consumers to boil for at least thirty minutes, because a home cook cannot verify that the inside of every bean held 100°C for long enough. The ten-minute figure is a laboratory result obtained on soaked beans, where heat reaches the centre far faster than it does in a bean that went into the pot dry. Use thirty minutes.
This is where the rest of this article does not apply. Our general advice — you need not soak, and you may keep the soaking water — does not apply to kidney-type beans. For them: soak, discard, boil in fresh water. The FDA also records that poisoning usually follows eating raw soaked beans, in salads or casseroles, which is the point worth holding on to: soaking is not itself protective. The boil is what does the work. If you do cook these beans from dry without soaking, the thirty-minute rolling boil in fresh water is the floor, and we will say plainly that we found no authority testing an unsoaked kidney bean at a gentle simmer — so we cannot tell you that route is equivalent. Soak them.
Intermediate heat is worse than either extreme
This is the part usually left out, and leaving it out gets the reasoning backwards.
- Do not use a slow cooker for kidney beans, or for dishes containing them. The FDA notes that casseroles cooked in slow cookers often reach internal temperatures of only 75°C or less, which is inadequate to destroy the toxin — and that several outbreaks have been associated with beans cooked in slow cookers.
- Longer and hotter, within that range, is not closer to safe. Bender and Reaidi — the same authors behind the ten-minute figure — report that heating beans at around 80°C increases lectin activity roughly fivefold, so that incompletely cooked beans may be more toxic than raw ones. Hong Kong's Centre for Food Safety reports the toxin still active after beans were cooked at 85°C for an hour, and University of Illinois Extension warns that slowly heating raw kidney beans in a slow cooker may increase their toxicity.
So a twelve-hour slow-cook is not a safer version of a six-hour one, and a slow cooker that runs hot is not a safer slow cooker. The band between warm and boiling is the worst place these beans can sit. The answer is a hard boil, briefly, rather than gentle heat for a long time.
Beans that have had their thirty minutes at a rolling boil can then go into a slow cooker, or anywhere else, quite happily. It is raw and barely-warmed beans that are the problem.
What this rule covers
It covers Phaseolus vulgaris: red kidney beans, white kidney beans and cannellini, black beans, pinto beans, and the rest of that species. It does not reach lentils, chickpeas or black-eyed peas, which are different species. But since the FDA says the lectin is found in many species of beans, the safe default is to give any pot of beans a hard boil at the start. It costs half an hour you were going to spend cooking anyway, and a few split skins.
On nutrition, briefly and carefully
Dried beans and lentils are a substantial part of what people mean by cooking from a dry pantry, and if you want composition figures — protein, fibre, minerals, per variety — the place to get them is USDA FoodData Central, which publishes the measured values. We are not going to paraphrase them into a claim here. What we will say is culinary: a pot of beans is one of the cheapest genuinely good things you can make from a shelf, and it gets better on the second one — cool it quickly, refrigerate it in its liquid within two hours, and use it within three to four days at or below 40°F (4°C), or freeze it in portions at 0°F (−18°C) or below. USDA guidance for cooked leftovers is three to four days at 40°F (4°C) or below.
About this article
Leaf & Larder has no licence and no stock yet, and nothing here is an offer to sell anything. This is editorial writing about cooking. It makes no medical or health benefit claims about any ingredient; the factual claims that needed a source have one linked above, and where we did not know something we left it out rather than guessing.