Pending External Review Key Facts
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Dry beans (Phaseolus vulgaris) have historically been a staple food. They are widely consumed throughout the world and are rich in protein, fiber, and various micronutrients.
- The per capita consumption of beans in the U.S. is approximately 7.5 pounds – much less than in other countries – and pinto is the most popular variety.
- Between 2000 and 2020, at least 149 overall bean-associated outbreaks were reported to CDC’s National Outbreak Reporting System (NORS), causing 3,415 illnesses, 82 hospitalizations, and no deaths.
- Although rarely the cause of foodborne outbreaks, cooked bean dishes that have been improperly cooled and stored can harbor pathogens, such as Clostridium perfringens.
- Cooking eliminates or significantly reduces antinutrients (e.g., lectins and trypsin inhibitors) found in raw dry beans, making beans safe for consumption.
- Bean consumption has been associated with weight maintenance, gut health, and a reduction in the risk for cardiovascular disease, some cancers, and other chronic diseases.
Pending External Review Content
Introduction
Domesticated independently in Mexico and South America about 8,000-10,000 years ago, beans are a staple food for much of the world’s population and a key ingredient in traditional recipes worldwide. Beans are known for their role in the Native American farming practice called three sisters, involving beans, corn, and squash. Beans fixed nitrogen in the soil for the corn and squash, corn provided shade for the squash and served as a trellis for bean plants, and squash plants helped retain soil moisture and prevent weed growth. Then, in the 15-16th centuries, dry beans were transported to Europe and Africa, quickly spreading to the rest of the globe.
Dry beans (Phaseolus vulgaris) belong to the diverse Fabaceae family, sometimes referred to as Leguminosae. Beans are often called by other names, such as legumes or pulses. However, not all legumes are beans (i.e., peanuts and feed crops like alfalfa are legumes), and beans harvested in the green state (e.g., green beans) are considered vegetables. Conversely, when harvested in the dried grain state, the edible seeds are called pulses. Dry beans are one of the major types of pulses, which also include other species like lentils and chickpeas.
There are many sub-varieties of P. vulgaris, including pinto, kidney, black, white, and navy beans. United States farmers plant about 1.5 million acres of dry beans a year, making the U.S. a global leader in production with pinto beans being the highest in production volume.
Beans are known as an economical source of protein. In addition, they are low in fat and a rich source of fiber and other important nutrients. Also, they are associated with a myriad of environmental and human health benefits, such as improved soil fertility and reduced risk of chronic disease.
Foodborne Outbreaks and Recalls
It is important to safely handle and store beans after cooking. Improper cooling and storage of cooked beans can result in unsafe levels of pathogens such as Bacillus cereus and Clostridium perfringens. Between 2000 and 2020, at least 149 overall bean-associated outbreaks were reported to CDC’s National Outbreak Reporting System (NORS), causing 3,415 illnesses, 82 hospitalizations, and no deaths.
Although not a common source of foodborne outbreaks, cooked beans have been linked to norovirus outbreaks due to person-to-person contact. Also, dishes containing cooked beans, such as refried beans and rice, have been the cause of C. perfringens outbreaks. One such outbreak was reported to the National Outbreak Reporting System and occurred in Wisconsin in 2012, resulting in 7 confirmed illnesses but no deaths.
Dry beans contain several antinutrients (e.g., lectins, trypsin inhibitors, saponins, and phytates) which can reduce bioavailability of healthful nutrients or cause other health complications. Of primary concern are lectins, which can cause hemagglutination reactions. Raw red kidney beans contain high levels of a type of lectin called phytohemagglutinins, consumption of which can result in nausea and vomiting. Although a few outbreaks in the United Kingdom in the late 1900’s have been associated with uncooked or undercooked kidney beans, there are no formally published instances in the U.S. Cooking eliminates or significantly reduces antinutrients, and heat-labile lectins are not a concern in properly cooked beans.
Production
U.S. Production
The United States ranks sixth in global production of dry beans. From 2015 to 2019, the 5-year average U.S. production of P. vulgaris was approximately 2,500 million pounds, over 950 million pounds of which were beans. North Dakota is the leading producer of dry beans, accounting for about 30% of U.S. production, and Colorado ranks sixth. In 2019, 22% of export volume went to Mexico, the top importer of U.S. dry beans.
Anasazi beans, mottled beans similar to pintos, were named for the Navajo term describing ‘the ancient ones’ and have historically been associated with the Four Corners region of the U.S. where they are still in commercial production.
Crop Characteristics
Beans are a warm-season row crop generally planted in May in the U.S, when soil temperatures are in the mid-60s F°. They should be planted in well-drained soil and a 3-year crop rotation helps to reduce pathogen problems. For instance, although dry beans are susceptible to white mold, crops such as corn and millet are not and thus serve as good rotational crops to help manage the disease. Beans are also sensitive to salt levels, with higher levels reducing yield.
Depending on factors such as the variety of bean and the climate, the grow season is about 4-6 months. Flower color differs with bean variety, and the flowers develop into pods. Beans form within these pods, ripening in the summer heat.
The U.S. harvest begins in August, 1-2 weeks after the plants change from a green to a yellow color. In some parts of the country, the harvest may continue into October. To minimize splitting and damage, beans should be harvested before a killing frost and when their moisture level is 15-18%.
Beans are often considered a sustainable crop, partially due to their ability to fix soil nitrogen and thereby contribute to soil health. Furthermore, bean agriculture has a lower carbon footprint and results in significantly less greenhouse gas production than that of other protein sources.
Food Safety
Dry beans are shelf-stable and can be kept safely at room temperature. They should be stored in a food-grade container or bag in a cool, dry, dark place. Warmer temperatures, higher humidity, and longer storage times can all contribute to longer cooking times.
Once cooked, it is important to cool and store beans properly. Shallower pans are recommended to speed cooling and limit bacterial growth. Leftovers should be refrigerated within 2 hours, and cooked beans can safely be stored in the refrigerator for up to 4 days or in the freezer for 1 year. In a retail or food service environment, cooked or refried beans should be maintained at 135°F or higher for hot holding.
More information on storing beans is available on FoodKeeper App.
Consumption
Approximately 7.5 pounds of beans are consumed per capita in the U.S. This is in stark contrast with other countries around the globe; for instance, the populations of some African regions may consume about 100 pounds per capita.
The most commonly consumed dry beans in the U.S. are: 1) pinto, 2) navy, 3) great northern, 4) red kidney, and 5) black beans. Beans come in many shapes, sizes, textures, and colors, and taste varies widely among different types. Beans can be cooked as a standalone food, however other common dishes incorporating beans include soup, chili, dips, curries, and various Mexican cuisines.
Nutrition
Beans are an economical and healthful food, providing an excellent source of dietary fiber, protein, and several micronutrients, such as folate. Dry beans have about 2-3 times more fiber than cereal crops (e.g., corn, rice). Over 90% of Americans do not consume enough dietary fiber; thus, beans could help close this fiber gap. The fiber and resistant starch in beans also results in a lower glycemic index than other carbohydrate-rich foods, like white rice and potatoes.
Beans are a naturally low-fat food with no cholesterol. Consumption is associated with many positive human health benefits, such as weight maintenance, gut health, and a reduced risk for chronic diseases such as cardiovascular disease and some cancers. For instance, results from a clinical trial demonstrated that eating pinto beans can help lower serum lipoproteins. Moreover, the dietary fiber in beans seems to have strong prebiotic effects beneficial to gut health.
Beans are often soaked before cooking to shorten the cooking time. A common myth persists that adding salt to beans prevents them from softening. However, the opposite appears to be true, and beans soaked in a salt like sodium chloride have significantly shorter cooking times than beans soaked in water with no salt. Another perception about beans is that they result in increased flatulence. However, this concern may be highly overexaggerated – many individuals do not report an increase in gas, and even those who do experience increased flatulence are likely to have symptoms subside as they quickly adapt to a higher-fiber diet.
Proper cooking eliminates or greatly reduces the antinutrients found in raw dry beans, such as lectins and phytates. However, these same antinutrients have also been linked to health promoting effects in small amounts. For example, saponins may help lower plasma cholesterol by forming insoluble cholesterol-complexes.
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