Dry Beans

drybeans

Key Factswiki_pending

  • Beans (Phaseolus vulgaris) have historically been a staple food and widely consumed source of protein and other nutrients.
  • Generally beans are very safe but must be cooked properly to destroy lectins which can be toxic.
  • Beans are annual row crops and include many different varieties.
  • The per capita consumption is approximately 7.5 pounds; pinto is the most popular variety.
  • A source of more than just protein, beans are referred to as a “superfood” due to their high nutritional value.

Introduction

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Foodborne Outbreaks

Most beans contain a class of protein called lectins, which have the ability to interfere with the cell membrane repair process that occurs as a part of digestion. If not destroyed by cooking, lectins can cause food poisoning (nausea, vomiting, and diarrhea). As such, dry beans must be cooked before they are consumed.

Red kidney bean (Phaseolus vulgaris) Poisoning and Kinkoti Bean Poisoning are caused by the consumption of raw or undercooked kidney beans. Onset varies from between 1 to 3 hours and is marked by extreme nausea, followed by vomiting, which may be very severe. Diarrhea develops somewhat later (from one to a few hours), and some persons report abdominal pain. Hospitalization may be required but recovery is usually rapid (3 – 4 h after onset of symptoms) and spontaneous. Phytohaemagglutinin, the presumed toxic agent, is a lectin found in many species of beans, but the highest concentration occurs in red kidney beans.

White kidney beans, another variety of Phaseolus vulgaris, contain about one-third the amount of toxin as the red variety; broad beans (Vicia faba) contain 5 to 10% the amount that red kidney beans contain. The syndrome is usually caused by the ingestion of raw, soaked kidney beans, either alone or in salads or casseroles. As few as four or five raw beans can trigger symptoms.

Several outbreaks have been associated with “slow cookers” or crock pots, or in casseroles which had not reached a high enough internal temperature to destroy the glycoprotein lectin. It has been shown that heating to 80°C may potentiate the toxicity five-fold, so that these beans are more toxic than if eaten raw.

Bacteria are a minor threat since the low moisture content of beans prevents their growth during storage. Mycotoxigenic molds produce toxins, mainly associated with cereals and their byproducts. Beans can be infected with molds, sometimes in the field, but more commonly during improper storage. Once mycotoxins are present, they can persist through processing into the final food product and pose serious health consequences to those who consume high amounts of toxin.

Soybeans are one of the top eight allergens. Crop rotations, certified seed, and cleaning of harvesting and hauling equipment will be essential to prevent cross-contamination of other foods with soybean allergens.

Production

History

Beans
Beans

Beans (Phaseolus vulgaris) have world-wide popularity and have been grown for over 7,000 years in south and central America. Beans belong to the family of plants called legumes. A legume is a plant that produces seeds in a pod (fruit) and has the ability to fix atmospheric nitrogen into the soil.

Dry beans and legumes are a staple food for a majority of the world’s population and represent a primary source of protein and other important nutrients in South and Central America, Asia, the Indian sub-continent and Africa. Beans are part of many national recipes, such as “feijoada” in Brazil, “Bandera Dominicana” in the Dominican Republic, “Gallo Pinto” in Nicaragua and Costa Rica as well as “Samp and Beans” in Southern Africa.

Historians believe beans originated in ancient Peru and Mexico. Over 7000 years ago they were domesticated and then slowly introduced to other parts of the world. With plenty of rainfall and long warm summers, North America presented an ideal climate for the cultivation of beans. Native Americans had skills for growing beans that were admired and adopted by the Pilgrims. They planted beans between corn rows, training the vines to grow up the tall corn stalks to reach sunlight. Succotash is a Native American dish authentically made from corn and kidney beans (lima beans are often used now). In some parts of the world, the method of growing beans between rows of corn is still used.

By the 1880s, American bean production started to boom. Michigan was the center of bean growing, and the crop soon attracted new growers in Idaho, Colorado, Montana, New Mexico, Nebraska and Wyoming. American dry bean production grew during World War II to meet increased demand of use by American servicemen around the world. The demand held steady after the War as American food relief efforts improved. Today 14 states produce dry edible beans and Michigan is the top state in production of black beans, cranberry beans, and small red beans.

U.S. Production

Each year U.S. farmers plant between 1.8 and 2.2 million acres of dry beans. The top three U.S. states producing dry beans are North Dakota (32% of total production), Michigan (17%) and Nebraska (11%).  The U.S. is the sixth leading producer of dry beans, behind Brazil, India, China, Burma and Mexico. Approximately, 20% of American-grown beans are exported.

Crop Characteristics

Beans are annual crops planted in spring when the soil is warmed up after the last frost date and usually harvested in early Fall (September) with 15-18% moisture, and using specialized harvesting equipment (threshers).

Dry Beans

Beans should be grown on well-drained soils as they are susceptible to water logging. Dry beans are usually irrigated during the production cycle. High quality water will help in prevention of on-farm microbiological contamination of dry beans.

Seeds inoculated with nitrogen-fixing bacteria will promote nitrogen fixation from the atmosphere reducing the required amount of synthetic fertilizer. Soil testing is done to determine baseline levels of minerals in the soil (nitrogen, phosphorous, potassium, zinc) and to adjust fertilizer application rates.

Integrated Pest Management (IPM) is used to prevent and control diseases weeds, insects, and diseases while minimizing risks to people and the environment. Use a combination of methods that work better together than separately (i.e. biological fungicides, crop rotation, irrigation practices, quality seed, variety selection, chemicals, etc.)

Food Safety

Dry beans are shelf-stable so they can be kept safely at room temperature. They should be kept in a cool, dry, and clean cabinet, preferably in the absence of oxygen and light. If unopened, they have a shelf-life of several years without losing quality.

Generally, pre-soaked dry beans can be cooked to the desired firmness in 60 to 90 minutes. Once beans are cooked, they are considered potentially hazardous and require temperature control for safety. Cooked beans in sealed containers may be stored up to 3 days in the refrigerator and several weeks (even months) in the freezer.

Consumption

Approximately, 7.5 pounds are consumed per capita in the U.S. The most popular dry beans in the U.S. are: 1) pinto, 2) navy, 3) great northern, 4) red kidney, and 5) black beans. There are many varieties of dry beans produced, so national and local preferences can almost always be met through careful specification of an appropriate variety. Beans come in many shapes, sizes, textures and colors, and taste varies widely among different varieties.

Nutrition

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Nutritionists have referred to beans as a “superfood.” Beans are high in nutrients, a great source of dietary fiber.  Research indicates including beans in diets can help prevent cancer and heart disease. They are rich in protease inhibitors which have been shown to make it difficult for cancer cells to invade healthy tissue. Beans are also rich in isoflavones which act as phytoestrogens in humans.

Beans are excellent sources of fiber, higher than other grains or flours and legumes appear to be valuable in lowering cholesterol and plaque in the bloodstream. The high fiber content of beans also helps to prevent blood sugar levels from rising too quickly after a meal, making beans a particularly good choice for those who suffer from diabetes, insulin resistance, or hypoglycemia.

Beans offer an excellent source of protein, particularly when combined with another grain choice such as wheat, corn or rice. Beans are high in iron and are an especially important part of the diet where iron deficiency and anemia are common. They are one of the best sources of folate, B vitamins, and antioxidants, all of which are essential for reproductive age women.  They are also a good source of potassium and are low in sodium.

Most legumes contain relatively high amounts of both dietary fiber and resistant starches. The soluble oligosaccharides found in legumes are not digestible by human intestinal enzymes alone. Instead, oligosaccharides such as raffinose and stachyose are broken down by bacterial fermentation in the intestines. Although some gas is due to the ingestion of air, the majority of flatulence is produced from bacterial fermentation. The byproducts of this degradation are hydrogen, carbon dioxide, methane, and sometimes sulfur, depending upon the bacteria. Normal intestinal processes move these gases out of the body in the form of flatus. Removal or alteration of the oligosaccharide content of legumes will reduce the amount of gas produced. However, it is not clear if changing the oligosaccharide component will alter the health benefits of legumes.

 

References

Authors

Harmonie Akers

Harmonie Akers

Pablo Rovira

Pablo Rovira

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