Is it safe to cook beans in a slow cooker? It’s not an issue I confront every day. However, when I cook beans, I want to do it safely.
If you are like me, you skim a lot of headlines from various sources. You hold those tidbits in your head until you forget them or find a way to put them into context.
Weeks ago, I saw something about the dangers of cooking beans in a slow cooker. I don’t recall where information came from, the particulars, or how reliable the source might have been. All that stayed with me were the words “danger“, “beans“, and “slow cooker.”
The only way for me to ever cook another bean in a slow cooker without worrying that I would poison someone was to find out the facts. Here is what I discovered about whether it is safe to cook beans in a slow cooker:
Kidney beans should not be cooked from raw in a slow cooker.
If you care about the scientific reason – it’s that the beans contain a protein, called phytohaemagglutinin, which is toxic. Even just a few raw or undercooked beans can make you quite ill.
Cooking the beans properly destroys the toxin. Soaking and then boiling the beans for at least 10 minutes (some authorities – including the FDA’s Bad Bug Book (Seriously – that’s the name of the publication. Don’t you love it!) – suggest boiling for at least 30 minutes) will eliminate the toxin.
Slow cookers may not reach a high enough temperature and hold it for long enough to kill the toxin. If you have a slow cooker recipe that calls for kidney beans, either cook them first or use canned beans, because they are pre-cooked before canning.
This precaution is most important for red kidney beans, but also applies to white ones. The latter are sometimes called cannellini beans. Red kidney beans contain about 3 times as much of the toxic agent as the white ones. However, white kidney beans can also cause illness if not fully cooked. I’ve also seen cautions about raw or undercooked soy beans (which contain a different toxin, called a trypsin inhibitor, which is also destroyed with the same type of proper boiling/cooking), but I rarely see recipes that call for cooking raw soy beans.
Now I can comfortably go back to cooking chili, enjoying fully cooked kidney beans in salad, and using my slow cooker again for bean soups and stews. 
Have you ever read, heard, or half-remembered a food safety tip that you’d like to check out? Leave a comment and let’s research it.
Susan Pridmore says
Really, really good information, Laura. I cook all my beans in a slow cooker and hadn’t read about kidney beans. I hadn’t cooked any this way, but now I’ll make sure I don’t in the future!
Rose Core says
I soak my red beans over night, then started cooking them with a ham bone, brought to a boil, simmering for about an hour and need to leave the house. Is it safe to switch them to a slow cooker on low? I am so worried about this now. Thank you.
Laura says
I am not a food safety expert. The sources I found suggested that you need to boil kidney beans for at least 10 minutes and maybe as long as 30 minutes. If that’s the case, and your “red beans” are kidney beans, then you would need to take them out of the slow cooker and bring them to a boil, then continue boiling them for 10-30 minutes. I’d suggest consulting an expert. Try the “Ask Karen” chat at the USDA https://www.fsis.usda.gov/wps/portal/informational/askkaren
Karen Gibson says
Hello good article , also heard potatoes stored to long give off a fatal toxic odor , thats fatal … Is this true ?
Laura says
Karen, Never heard that one – I’ll try to check it out. Thanks for stopping by.
Marie Seibel says
I’ve been cooking beans (not kidney, but rather pinto, navy, black and black-eyed peas) in a crock-pot for over 45 years. No one has been gotten sick yet. Don’t plan to change unless they decide to ban crock-pots…
Laura says
Marie, Glad you’ve enjoyed cooking beans in your crock pot/slow cooker. The only beans subject to the caution mentioned in the post are kidney and you said you don’t cook them in the crock pot.
Burgundy says
I’ve cooked dark red kidney beans even with out soaking or boiling for years in my crock pot. Usually for red beans and rice. No one has ever gotten sick, thank goodness. But I will boil them first from now on. Thanks
Laura says
Burgundy, Your experience shows that not everyone who does things in a less-than-absolutely-safe way will get sick, but glad that you’ve decided to be extra careful from this point forward.
BB says
I got violently sick from making pinto beans in a Crock Pot once. I’ll never do it again. I use my Instant Pot for beans now. It’s much faster anyway, and the beans come out great.
Laura says
Interesting that slow cooker pinto beans made you violently ill. In theory, you should be able to make pinto beans safely in a slow cooker. In any event, I’m glad you found a way to make them that has been delicious and trouble-free.
John says
Sorry to hear about that. I have not been boiling my pinto beans before slow cooking but I do start them on high then switch to low after the slow cooker heats up to boiling… today I checked the temperature before switching to low and confirmed that it was 210F. I would have been happier with 212F but I figure 210 is close enough for pinto beans.
Deanna Miller says
I always soak overnight and rinse well. I’m not a fan of kidney beans in general but I have used them…. no one got ill but I also like to leave it running high for the first hour or so to get it really going before lowering temp and cook for about 8 hrs (mine seems to run a little hot anyway). I promise I’ll pre-cook kidney if I use them again. Thanks for the advice!
DAJ says
Is it possible this bit of food news regarding red kidney (& other) beans was initiated by the manufacturers of the various pressurized multicooking pots that have flooded the market in recent years?
Laura says
I don’t think the food news about how to safely cook kidney and other dry beans comes from manufacturers of pressurized cooking pots. I found it through the FDA and here is another cite – from Kansas State U https://www.johnson.k-state.edu/health-food-safety/agents-articles/do-not-cook-dry-beans-in-slow-cooker.html#:~:text=Do%20Not%20Cook%20Dry%20Beans%20in%20Your%20Slow%20Cooker&text=All%20beans%20contain%20a%20compound,be%20toxic%20at%20high%20levels. the issue is not which type of pot you use, but making sure that the pot gets hot enough to boil the beans and not just stay at a low temperature that allows the toxin to breed.
CrAzY BoB says
Was happy to see your comments aside from all the other views about it on the interweb … Much appreciated …
Donna says
I am planning to make a red bean soup dessert that you get in Chinese restaurants and was just going to put the red beans in the slow cooker with rock sugar, won’t be doing that now! Will make sure to boil the beans first, Thanks for the info.