Cooking beans in a crock pot

Posted in Diet & Nutrition on August 4, 2013 by NebraskaHealth.com staff.  Last modified on April 21, 2019. Read disclaimer.

Most Popular Topic:

• Danger of cooking beans in slow cooker

Sample Recipe:
Makes 10 servings
Serving Size: 1/2 cup

Ingredients

• 1-pound dried beans (pinto, black, garbanzo, etc.)
• 4 tablespoons of salt
• Water
• 1 onion, chopped (optional)
• Pepper to taste

Directions

1. Put dried beans in the colander and rinse in cool running water. Rinsing washes away dirt and makes small pebbles and other contaminants easier to spot. Remove any broken or discolored beans.
2. Put rinsed, dried beans in a large cooking pot. Add a few tablespoons of salt and enough cold water to cover plus an additional 2 inches since the beans will expand. Cover with a lid or plastic wrap and either put in the refrigerator or leave at room temperature overnight. (Soak a minimum of 5 hours up to 24 hours.)
3. Drain the beans, rinse and place in stovetop cooking pot with 1 tablespoon of salt and enough fresh water to cover plus 2 inches.
4. Boil beans for a minimum of 10 minutes on stove top. Read "Why it's important to boil beans before putting in slow cooker."
5. Transfer contents to slow cooker and add onion and pepper a pinch of salt if desired.
6. Cook on low until tender.
7. Drain if desired.
8. When beans have cooled, store excess in zip lock bags and freeze.

Food Preparation Tip: Experiment with adding different spices when cooking dried beans.

Pinto beans can be mashed to make refried beans with no added fat. Refried beans can be used in tacos, taco salad, or as a main dish substitute.

Nutrition Information per Serving

110 Calories, Total Fat 0g, Saturated Fat 0g, Protein 7g, Total Carbohydrate 20g, Dietary Fiber 7g. Good source of iron. Analyzed with pinto beans.

Dangers of cooking beans in slow cooker

Beans are a very safe food when cooked properly. However, there is a tasteless but potentially toxic protein called lectin phytohaemagglutinin (sometimes referred to as kidney bean lectin) that's present in many plant-based foods but is of special concern when we're slow-cooking beans. (It's believed that this toxin helps plants protect themselves against insect pests and fungus.)

The good news is that phytohaemagglutinin isn't dangerous when consumed in the small quantities that most foods contain. The bad news is that certain beans, especially red kidney beans and black (turtle) beans have such high concentrations of this toxin that, unless the phytohaemagglutinin is reduced and destroyed in the cooking process, it can cause serious food poisoning in humans and animals.

In their raw state, red kidney beans contain between 20,000-70,000 hau (hemagglutinating units) of this toxin. After fully cooking these beans at high heat, however, the amount drops dramatically to a safe 200-400 hau.

How bad is this toxin? Eating as few as 4 or 5 soaked, raw red kidney beans can cause food poisoning... and no one is immune! Worse yet, undercooked beans can be even 5 times more toxic than the raw beans, depending on the cooking temperature!

Because of this food poisoning concern, it is important to follow these two steps if you're going to slow cook dried beans:

1) Presoak beans for at least 5 hours before cooking and discard that soak-water before cooking. Soaking leaches out some of the toxin into the soak water.
2) Add new water (enough to cover plus 2 inches) and bring beans to a rapid boil for a MINIMUM of 10 minutes before adding them, along with the rest of your ingredients, to the slow cooker for the remainder of the cooking process. (Some experts even suggest that home cooks should presoak beans for 12 to 24 hours and boil them a minimum of 30 minutes to make sure the full pot reaches the sufficient temperature for the sufficient amount of time.) 10 Minutes of rapid boil is enough to break down and destroy the great majority of the toxin, making it harmless.

The bottom line is, "many dried beans, including kidney beans, should never be cooked solely in a crock pot or slow cooker because they will never reach a high enough temperature for a long enough period of time to destroy enough of the phytohaemagglutinin to make the beans safe to eat. It is also not safe to eat these beans raw or sprouted or ground into flour because of the high levels of toxin."

"But I've often cooked beans in a slow cooker and never gotten sick!"

Not all beans contain the extremely high levels of phytohaemagglutinin toxin found in red kidney beans (though they are still potentially dangerous). For instance, white kidney beans contain only 30% and broad beans have only 5-10% the levels that are found in red kidney beans.

If you're still concerned, a safe, fast option for cooking dried beans is to use a pressure cooker. This assures that they will cook at the safe, boiling temperature for an adequate amount of time.