ECHO Development Notes 100
Winged Bean Selections
From A to Z, p. 70
HAVE YOU TRIED WINGED BEANS, PSOPHOCARPUS TETRAGONOLOBUS? There has been so much promotion of the winged bean that I find myself thinking all of our readers know about it. However, it is too important a plant to fail to bring it to your attention. This legume will vine up a four-meter pole. Nearly all parts are edible and high in protein. The leaves can be cooked like spinach and are quite tasty. The long four-sided pods with serrate "wings" running the length of the corners can be eaten like green beans. The dried seeds are the nutritional equivalent of soybeans. Fried flowers taste like mushrooms. When production is over, the stems can be fed to cattle, and most varieties have edible tubers that contain up to eight times the protein of an Irish potato.
The winged bean is native to the Asian tropics. When I have tried growing green beans during the hot, humid Florida summers, they have always been killed by disease or insects before they could produce pods. Winged beans, on the other hand, seem to resist almost everything except nematodes if well fertilized and watered.
We can send you seeds of a few varieties and a short technical note on the cultivation, preparation, and nutritional value of winged beans. Most varieties only bloom during short days, so they do not bloom and produce pods in Florida until mid-October. On the other hand, there are a few day- neutral varieties that get excellent yields right through the long days of summer. If you are far enough from the equator that this can be a problem, request the day-neutral seed from us. For others, we will send a selection of perhaps four regular varieties.
Winged bean seeds need to be scarified before planting. Alan Lee had less than 50% germination a month after planting his winged bean seeds. "I dug up the ungerminated seeds and nicked them all a few times with the corner of a razor blade, then replanted them. Within a week several had germinated and I expect more." Seeds will not germinate until they have absorbed water. Scarification softens or opens the seed coat so water can be absorbed. Nick the seed with a knife or file or strike it across cement as in striking a match. Some seeds are soaked overnight. (Leucaena seeds are put in water that has just been boiled then left overnight. If you have any hard seeds that fail to germinate, it is possible the seed may still be viable. It may need to be scarified.)
After fourteen years of growing winged beans and distributing seed, we have come to believe that their potential has been overstated. Only very special recipes make the dried seeds appealing in taste. Pods are acceptable to the North American taste, but other beans are usually preferred. Leaves and raw flowers are quite good but probably limited to household use. No one at ECHO cares much for the tubers. (If the beans were propagated by tubers year after year, as is the practice with some other beans, it is possible that they might develop more in size and be more useful, although the texture might deteriorate.) Our impression from our network is that no one has had a major success introducing winged beans. In its countries of origin, winged bean products continue to be popular. It is worth trial for its many virtues, but do not expect as much of its market potential as early reports indicate.
From A to Z, p. 277
HOW ARE WINGED BEANS COOKED? Peace Corps volunteer Henry Kobie in Liberia wrote that he has had considerable success introducing winged beans, but folks know little about how to cook them. I thought our readers might be interested in what we turned up for him. I have often wondered why a plant that has received so much attention, because of its potential both for production in hot humid climates and also for its high nutritional value, is not making a greater global impact. Uncertainty on how to use it is no doubt part of the problem.
The most difficult question is how to prepare the mature seeds. A few years ago I asked a researcher at CIAT in Colombia why they were not eaten on a large scale. He said that if I had ever tasted them I would know! The long cooking time required to soften whole, mature beans is also a problem in firewood-short countries. I think we can take a lesson from the soybean. In the countries where soybean is an important food, they have developed rather elaborate and unusual processing methods (making "milk", tempeh, etc.). The winged bean seed is nutritionally comparable to the soybean and, I suspect, requires similar processing methods.
A friend here in town makes a spread from ground up mature winged bean seeds that I quite enjoyed. He adapted this and other recipes from soybean recipes in "Recipes for a Small Planet." Perhaps you could adapt it to local conditions, at least for the palates of our American readers. The ingredients are 2/3 c dry beans cooked until tender, a large onion sauteed in oil with a bit of garlic, juice of 2 lemons, a tablespoon soy sauce, 1/4 cup sesame butter (or any nut butter), 1/2 cup roasted and ground sesame seed, and 1/2 tsp salt.
The National Academy of Sciences' most recent booklet on the "Winged Bean: A High Protein Crop for the Tropics" (1981) is quite helpful. The following are excerpts adapted from that booklet, with my comments in [ ]. Pods are the most popular part of the plant in most countries where the bean is grown and the easiest to introduce as food. They can be eaten raw or used in salads, soups, stews and curries and may be boiled in water or coconut milk or sauteed in oil. [If you grasp the pod in both hands it should be flexible. If not it will be too stringy to eat. Varieties differ in how long pods can grow before becoming fibrous.] In Papua New Guinea, pods that are too fibrous to eat whole are often steamed in oil drums or the "mumu" pit, or baked in open fires; the seeds and mucilage are then scraped out and eaten. [This is probably of higher nutritional value because protein accumulates as the pods mature.] Alternatively, the half-ripe seeds can be removed from the pod and cooked. The immature pod provides primarily bulk with comparatively low energy content, but is valuable for the minerals and vitamins. No adverse effects have been reported from cooked immature pods. [A missionary recently told me that he required his workers to eat at least one raw bean at the beginning of each day. They were seriously under- nourished. They soon began feeling so much better that they ate it on their own and requested seed.]
The seeds are the most nutritious part. They can be steamed, boiled, fried, roasted, fermented, or made into milk, tofu (bean curd) or tempeh. Because of antinutritional substances, they should be soaked overnight, then boiled in water until tender, with the soaking liquid discarded. [I understand that some varieties from regions that grow winged beans primarily for tubers may have more toxic substances present in the seeds, so be cautious if collecting your own varieties in such places.] If seeds are soaked in a hot, 1-percent sodium bicarbonate [as in Arm and Hammer soda] solution, the hard seed coats are more easily removed. Mature seeds are more difficult to dehull by this process because the cotyledons swell and press firmly against the hull. When fried or baked, they make a delicious nut-like snack. The high temperature breaks open the tough seed coat. It is not certain, however, whether this method of cooking removes the antinutritional substances. Sprouted winged bean seed can be used as an alternative to mung bean sprouts. Extracting oil from winged bean seeds leaves a high-protein meal. Infants fed winged bean meal suffer little or no flatulus discomfort [gas]. In storage the seeds show remarkable resistance to bruchid beetles which are such a bad pest of stored legumes.
Tubers have several times the protein of potatoes. They can be boiled, steamed, fried or baked. The brown skin peels off readily after 40 minutes of cooking, leaving a white or cream-colored flesh that is firm and moist, with a distinctive nutty, earthy flavor. They are always eaten cooked.
Winged bean sprouts and shoots may be eaten raw or cooked as green vegetables. The top three sets of leaflets are the most tender; they taste slightly sweet. They have an average amount of protein, but are exceptionally high in the amino acid tryptophan. Thus even a small amount of the leaves can greatly improve tryptophan-deficient diets, e.g. those based on corn. Adding cooked leaves to diets of weaned infants and preschool children is recommended for the minerals and vitamin A precursor. The latter is among the highest ever recorded in green leaves of tropical plants. Excessive consumption of raw leaves has produced dizziness, nausea and flatulence, so large amounts of raw leaves should not be encouraged. Properly cooked they are safe in quantity. Also flowers can be eaten raw. When steamed or fried they have the color and consistency of mushrooms.
Commercial efforts were just getting underway when the book was published. Efforts are underway to make flour. A gruel for weaning infants has been produced in Ghana. Mixed with corn, it provides the nutritive equivalent of milk. In Thailand a similar gruel made of winged bean meal, rice, and banana is being fed to refugees from Cambodia. Because of its similarity to the soybean, many soybean recipes are being tried. Tempeh and tofu are made commercially in Indonesia. Both white milk and a chocolate-flavored milk have been made from the seed in Thailand and sterilized for longer shelf life. Researchers have made tasty snacks from tubers sliced thin, fried and salted, or softened in sugar syrup. Immature pods are used in pickles commercially in South India. One researcher in Indonesia has made a coffee substitute by roasting the seed (the grounds are edible) and a tobacco substitute from the dried leaf. Both of these should be free of alkaloids.
By the way, the dry pod left after threshing contains 10% protein and has been tested satisfactorily in animal feeds. In Thailand this pod residue is being used successfully as a medium for growing straw mushrooms.
Let me know if you are able to adapt any of these ideas and what the people's reactions are. We would be especially interested to know of any successful introductions you have made and how the local people prepare them. Winged beans are native to hot, humid tropical regions. If you have had success introducing them into other climates we would especially like to know the details (e.g. in dry or high altitude regions).
WINGED BEAN RECIPES. Dr. Andy Duncan sent us several recipes; write us for a photocopy. Dr. Frank Martin sent this information on winged bean seeds: "Probably no region of the tropics uses the seeds regularly as food. Seeds are parched in Java, but probably only immature seeds are used. They are used for making a vegetable curd similar to tofu from soybean, but our experience showed that such curds are definitely inferior to those of soybean. The 4-hour cooking time is an obstacle [to use of the seed]. ...The heavy seed has been suggested to cause abdominal pain. The evidence is persuasive that dry winged bean seeds are difficult to eat."
This was "confirmed in tests of 20 different lines.... Seeds left to soak absorbed water slowly, and some not at all. Three or four hours were required to cook soaked beans, and then some remained hard and unswollen. Cooked beans were harsh and nut-like, acceptable as an occasional food, but not attractive to the eye or the palate. When cooked beans were ground into soups and flavored with other ingredients, an acceptable product was obtained. Although variety differences were seen, these were not sufficient to permit selection of lines of acceptable value."
Frank suggested a different method of cooking. "The beans treated in this fashion are very soft. Even the seed coats are pliable and edible. Such beans have a mild and agreeable flavor comparable to that of other beans. Tests so far suggest that people who eat beans regularly accept them readily. [They can be] used in many traditional dishes. Not all varieties are equally suited to this technique. In many, a few seeds remain hard, and many are intermediate. In these lines, however, the softened seeds can be separated from the hard seeds with a large mesh screen. Here is that better method:"Measure the volume of beans to be cooked. Rinse and add 5 volumes of water. To the water add 1% sodium bicarbonate sold as soda or baking powder [about 1/2 teaspoon per cup of water]. Boil the beans and simmer for 3 minutes. Remove from heat and soak the beans in the solution overnight. The following day, discard the soaking water, rinse twice with fresh water and boil in double their volume of fresh water for 20 to 25 minutes."
From ECHO Development Notes, April 2004, Issue 83
Bulk Seed from ECHO's SeedbankThe following seeds may be purchased from ECHO's Seedbank in small bulk quantities.
Psophocarpus tetragonolobus 'Day-Neutral Winged Bean': A climbing leguminous vegetable that thrives in hot humid zones. The pods, beans, leaves, tubers, and flowers are all edible, which is why it has earned the name "super market on a vine." This particular variety does not require short days for seed production.
From ECHO Development Notes, October 2007, Issue 97
FROM ECHO’S SEEDBANK
Winged Bean Revisited
By Tim Motis
Winged bean (Psophocarpus tetragonolobus), an amazingly productive and multi-purpose legume, grows as a vine typically staked on 1.5 to 2 m (5 to 6.5 ft) poles or trellises. Likely originating in the Asian tropics, it thrives in hot, humid areas and grows at elevations up to 2000 m (6562 ft).
In 1975, the US National Academy of Science published a study of winged bean. An incredible amount of interest and research followed. The reasons for this were many:
When ECHO first wrote about winged bean (Amaranth to Zai Holes, pages 70-71), we had been distributing winged bean seeds for 14 years. At that time, our overall impression from our network was that there had been no major success introducing winged bean outside of countries where they were already popular. Harvest trial reports since 1995 indicate no change in that assessment. As pointed out in an earlier EDN, several attributes of winged bean limit its potential:
Yet, we continue to receive numerous requests from overseas for winged bean seeds. Thus, it merits thought as to how this crop might be of benefit.
A starting point, of course, is to find out if winged bean will grow well in your area. Consider climatic conditions in your project area. Danny Blank, ECHO’s farm manager, comments that winged bean fills a niche because it is “a bean that produces—actually thrives—under hot, humid and wet conditions.” Also consider and experiment with several varieties of winged bean. This is the beauty of ECHO’s small seed packets. Each packet contains about 40 seeds, enough to try on a small plot. Organizations working to help small-scale farmers may request, free of charge, one packet each of any or all of the varieties shown in Table 4. Others are asked to send $4.00/packet to cover seed and mailing costs. Packets including a mix of several varieties are also available—save seed from any plants that do well in your area.
If a planting fails, think about why it failed before completely giving up. Problems reported by our network are poor or delayed germination, cool temperatures [especially at elevations higher than 2000 m (6562 ft)], leaf-cutter ants, heavy rain (likely combined with poor drainage), and extreme drought.
Assuming winged bean grows in a particular area, its acceptance by farmers will likely depend on whether or not it addresses a need not met with other crops. For instance, it might succeed where protein is lacking and other beans are either not available or are less disease resistant than winged bean.
In finding a niche for winged bean, determine which part(s) and attributes of these plant parts will be of greatest benefit to farmers. Varieties differ in how much of a particular plant part they produce. Among seven varieties evaluated in a recent trial at ECHO, ‘Ribbon’ and ‘Bogor’ were the highest pod and seed producers (Table 4). Varieties also differ with respect to pod color, size and shape. The large, crimson-red pods of ‘Chimbu’ may give it extra market appeal. Pods of ‘Flat’ and ‘Square’ are shaped as their names imply; with these varieties, shipping-related damage to the pod wings would probably be minimal.
Growing practices influence production of various parts of the plant. Tall stakes favor pod and seed production over tuber production. In Malaysia, seed yields were maximized to 6.26 t/ha by supporting vines on 2 m (6.6 ft) stakes, harvesting an initial crop of mature pods, and then ratooning at 19 weeks after seed germination. Ratooning involved cutting the plants 30 cm above the ground, resulting in regrowth of vines and pods.
Success introducing winged bean also requires careful thought as to how to prepare it for eating and then transferring that knowledge to local farmers. A few quotes from members of ECHO’s overseas network of community development workers illustrate the point: “People don’t like the taste although they did not prepare them correctly.” “Locals do not really know this vegetable yet. We are still trying to promote it as part of their diet.” “My experience…is that they prefer not to try new cultivars or vary their diet.”
When growing winged bean for fresh pods to be eaten like green beans, the pods must be harvested while young and flexible enough to bend without breaking. When harvesting mature pods for dry bean production, consider ways to reduce the cooking time needed to soften the seed coats. A method suggested by Dr. Frank Martin and quoted in Amaranth to Zai Holes (page 279) reads as follows: “Measure the volume of beans to be cooked. Rinse and add 5 volumes of water. To the water add 1% sodium bicarbonate sold as soda or baking powder [about ½ teaspoon per cup of water]. Boil the beans and simmer for 3 minutes. Remove from heat and soak the beans in the solution overnight. The following day, discard the soaking water, rinse twice with fresh water and boil in double their volume of fresh water for 20 to 25 minutes.” For other cooking hints, request or download (www.echotech.org) a technical note entitled “Winged Bean Recipes.”