Be Careful With Red Kidney Beans in The Slow Cooker

| 1/31/2013 2:46:38 PM

Bowl of ChiliWhen the weather is cold and raw, good cooks turn to their crockpots to provide the long-simmered dishes that winter appetites demand. We seem to hunger naturally for the flavors of chilis and soups, stews and pot roasts.

One favorite winter dish that requires a bit of caution, however, is the big bowl of crockpot beans. Red kidney beans — commonly added to chili — can be the source of Red Kidney Bean poisoning, caused by a toxin called Phytohaemagglutin, or kidney bean lectin.

Other beans also contain the toxin, but in varying amounts. Red kidney beans have 20,000 to 70,000 heagglutinating units (hau), while white beans contain about a third as much; broad beans like favas have as little as 5 percent of the amount in red kidney beans.

This toxin can make you feel pretty crummy. Raw or undercooked beans can cause nausea, vomiting, diarrhea and abdominal discomfort within 1 to 3 hours. Recovery usually is complete within 4 hours of the symptoms’ appearance, though some people have been hospitalized.

Fully cooked or canned beans are always safe to eat. But undercooking can actually raise lectin activity. That’s why it’s best to use canned or fully pre-cooked kidney beans in crock pot recipes that call for beans.

For more information, visit the Penn State Extension explanation at

2/17/2016 1:04:45 PM

So, if we can the beans ourselves, they should be safe? Since our family meals now typically include just the 2 of us, a whole pound of beans is a bit much to cook. And for all the trouble and time, I may as well cook a large batch, since smaller batches aren't cooked any faster. But, what to do with the extra beans? I can a lot of foods, and am the proud owner of a pressure canner. Would the processing time in the canner be enough? Does anyone know? TIA, Michelle

2/15/2016 10:02:58 PM

Hey I agree with you Frugal Girl about avoiding tinned foods. This is my ‘No wind' method of cooking beans that I have used for 40+ years for meals or preserving for winter use. Red beans should always first be soaked overnight in water. Soak any beans that cause you wind actually - no need to suffer twice) (It is doubtful that any commercial varieties are ever soaked - hence many avoid lovely beans). Cover beans with soak water to a higher level as the beans swell up when soaked. TIP OFF THIS SOAK WATER that contains lectin (AKA ‘The Wind machine) and boil the beans in fresh water. After boiling for 15 mins, pour off this initial cooking water too, and then add new fresh cooking water (+ any herbs, but no salt until fully cooked) and bring to the boil, then simmer until a bean can easily be squeezed in your fingers. All beans and red beans vary crop to crop, so cooking times can vary too. Always do the squeeze test. That's it. Kia Ora from Marie down under in New Zealand!

2/3/2014 12:36:42 PM

Great point to bring about the toxin in kidney beans and other beans. But the best way to take care of the toxin is described in the excellent bean cookbook, Dried Beans & Grains (The Good Cook, Techniques & Recipes), from Time Life Books. The book explains that the toxins in large beans like kidney beans can be destroyed by bringing the beans to a boil for at least 10 minutes. The smaller legumes like lentils and the like need to be boiled for at least 2 minutes. Canned beans don't always get boiled when processed, and the can itself poses the scary danger of BPA. A few companies are now selling cooked beans in the frozen food section, probably for this reason.

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