Cooking dried beans and lentils: soaking, salt, acid and hard beans
Dried beans and lentils are cheap, keep for months and cost less per portion than canned, but they come with a few rules that decide whether they turn out creamy or stubbornly hard. This guide covers sorting and rinsing, the two common ways to soak, how to simmer, when to add salt and acidic ingredients, and the usual reasons a pot of beans refuses to soften. It also covers the one safety rule that matters most: red kidney beans must be boiled hard before they are eaten. None of this comes from our own testing. It is general cooking knowledge, and the pack instructions for your beans come first.
Before you start: sort and rinse
Tip dried beans or lentils onto a tray or plate and pick out any small stones, grit, shrivelled or broken pieces. Then rinse them in a sieve under cold water. This matters more than it sounds, because a small stone is easy to miss once the beans are cooked.
Beans that are very old, or have been stored somewhere warm and damp, can take far longer to cook and may never soften fully. Buy from a shop with a steady turnover, keep them in an airtight container in a cool, dry cupboard, and use them in good time rather than keeping the same bag for years.
Which need soaking
| Type | Soak? | Notes |
|---|---|---|
| Red and yellow split lentils | No | Cook quickly and break down into a puree. Good for dal, soup and thickening. |
| Brown and green lentils | No | Hold their shape reasonably well. Good for stews, salads and fillings. |
| Puy, French green and black lentils | No | Stay firmest. Good for salads and sides. |
| Split peas | No | Soften into a thick puree, as in pea soup. |
| Chickpeas, black, pinto, cannellini, butter beans and similar | Usually yes | Soaking shortens cooking and helps them cook evenly. Unsoaked beans can be cooked but take much longer. |
| Red kidney beans | Yes, then boil hard | See the safety section below. Never skip the hard boil. |
Two ways to soak
- Overnight soak: cover the beans with plenty of cold water, at least three times their volume, because they swell a lot. Leave them for 8 to 12 hours or overnight. In a warm kitchen, soak them in the fridge so they do not start to ferment.
- Quick soak: put the beans in a pan with plenty of water, bring it to the boil, boil for about 2 minutes, then take the pan off the heat, cover it and leave it for about an hour.
Either way, drain the soaking water and cook the beans in fresh water. Many cooks believe discarding the soaking water reduces some of the sugars linked to wind, though cooking them well and eating them regularly also matter.
Adding salt to the soaking water is a common technique. Dissolve a little salt in the water before the beans go in; it tends to give softer skins and fewer split beans. Rinse the beans after soaking.
Simmering
Put the drained beans in a large pan and cover them with fresh water by a few centimetres. Bring them to the boil, skim off any foam that rises (it is harmless but can make the pot boil over), then turn the heat down to a gentle simmer with the lid partly on. A hard, rolling boil for the whole time tends to burst the skins before the middle is cooked.
Top up with hot water if the level drops below the beans. Cooking times vary a lot with the type, size and age of the bean, so the packet is a guide and tasting is the test. A cooked bean is soft and creamy all the way through when you squeeze it or bite it, with no chalky centre. Taste several, because they do not all finish at once.
Once they are done, leave the beans to cool in their cooking liquid rather than draining them straight away. They stay plumper, and the liquid is useful for soups and stews. Chickpea cooking liquid can be reduced and used as aquafaba.
Salt, acid and sugar: what slows softening
An old rule says that salting the pot makes beans hard. Many modern cookery writers and test kitchens disagree: salting the cooking water seasons the beans through and does not stop them softening. Add salt at the start or partway through, whichever you prefer.
Acid is a different matter. Tomatoes, vinegar, wine, lemon juice and other acidic ingredients slow down the softening of bean skins and flesh. Sugar and molasses also slow it, which is why baked bean recipes often cook for a long time. If a recipe combines beans with tomato or another acid, the safe approach is to cook the beans until they are tender first, then add them to the sauce.
Lentils follow the same rule, though they cook faster and are more forgiving. A lentil dish with a lot of tomato will still soften, but it may take longer than the packet says.
Why some beans stay hard
- Old beans: the most common cause. Beans stored a long time, especially somewhere warm, can resist softening however long you cook them.
- Acid or sugar added too early: tomato, vinegar or molasses in the pot from the start slows softening.
- Hard water: water high in calcium and magnesium slows softening. Cooking in softened or low-mineral bottled water can help.
- Not enough time or too low a simmer: some large beans simply need longer than expected. Keep tasting.
- A mixed batch: beans of different ages or sizes in one bag finish at different times.
A small pinch of bicarbonate of soda in the soaking or cooking water makes the water alkaline and helps stubborn beans soften. Use very little, because too much makes them mushy and gives a soapy taste.
Kidney bean safety
Raw and undercooked red kidney beans contain a natural toxin called phytohaemagglutinin, which can cause severe vomiting and diarrhoea, even from a few beans. Soak dried kidney beans, drain them, then boil them in fresh water at a full, rolling boil for at least 10 minutes (some food safety agencies, including the US FDA, advise 30) before turning them down to simmer until tender. Gentle heat alone is not enough, and undercooked beans can be worse than raw ones.
This matters most for slow cookers, which may never reach a full boil. Boil soaked kidney beans hard first and then add them to the slow cooker, or use canned kidney beans, which are already cooked. Some other beans contain the same toxin in smaller amounts, so the same boil-first habit is a sensible default for any dried bean going into a slow cooker.
Pressure cookers
A pressure cooker or electric multicooker cooks soaked beans in a fraction of the stovetop time. Follow the manufacturer's times and fill limits, because beans foam and swell; most manufacturers say not to fill the pot more than about half full for beans and lentils. Let the pressure release naturally, since a fast release can make the beans split or spit foam from the valve.
Yield, storing and freezing
Dried beans roughly double or triple in volume once cooked, so cook more than you need and keep the rest. Cool cooked beans quickly, then keep them covered in the fridge and eat within 3 to 4 days, or sooner if your local food safety guidance says so. They freeze well in portions with a little of their cooking liquid, and can go straight into soups and stews from frozen.
Gluten note
Plain beans, lentils and chickpeas are naturally gluten-free, but dried pulses can pick up stray grains of wheat, barley or rye in the field or during packing. Sorting helps, but it cannot remove dust or fragments. If you need to avoid gluten strictly, choose packs labelled gluten-free and read the label on any seasoned or ready-made product. Coeliac and allergy questions belong with a doctor or dietitian.
What this guide is based on
- The soaking methods, the effect of acid, sugar and hard water on softening, and the reasons beans stay hard are general cooking knowledge, not results from our own testing.
- The soaking time (8 to 12 hours), the quick soak (boil about 2 minutes, then stand about an hour) and the pressure cooker half-full limit are commonly given starting points, not results from our own testing; follow the pack and the manufacturer.
- The kidney bean advice (soak, then boil hard for at least 10 minutes, or 30 by some agencies) is standard food safety guidance. The 3 to 4 day fridge limit for cooked beans is common general guidance for leftovers; some national guidance, such as the UK's, is shorter.
- Views on salting the cooking water differ between older and newer cookery advice; this guide reports the common modern view, not our own test.
- This guide is general information, not medical or dietary advice.