Velvet beans are being grown more widely, because corn yields can be increased considerably by intercropping with velvet beans. (For other beneficial effects, see the following article).
Velvet beans have potential to be a significant food. Bean yields are high, sometimes when common beans fail due to drought. The beans are nutritious, with a high protein content. Many recipes have been developed for their use and people enjoy the taste.
Herein lies a major dilemma for farmers and their advisors. About 5% of the weight of the bean is a psychoactive substance called “dopa.” Dopa is still a commonly prescribed treatment for Parkinson’s disease, though it has side effects such as uncontrolled muscle twitches and, in extreme cases, even psychotic disorders including schizophrenia.
Dr. Rolf Myhrman brought both good and bad news on the subject at ECHO’s Conference for Agricultural Missions. In his lab at Judson College in Illinois, he has been studying dopa in velvet beans from different countries and after different methods of preparation for human consumption.
One thought has been that one might get rid of the dopa by removing all the seed coats. This can be easily done by hand after cooking. However, Rolf was unable to detect any dopa in the seed coats.
One major use of velvet bean by humans is to make a coffee substitute. (The coffee is called “nutri cafe” in Central America and the bean is sometimes called “Nescafe bean.” Ideally, the dopa would either be destroyed by the heat or remain in the grounds, leaving the coffee free of dopa.
Rolf found, on the contrary, that making “coffee” is an ideal way to extract intact dopa! “An 8ounce cup of velvet bean coffee can be expected to contain between 250 and 300 mg of dopa. For comparison, a physician might start a Parkinson’s patient on 5001,000 mg of dopa per day.” [The other side of the question is whether someone with Parkinson’s disease, but who cannot afford prescription dopa, could drink velvet bean coffee as a treatment. Do any physicians in our network have ideas on this?]
The good news is that a large fraction of the dopa can be removed from beans by grinding and soaking in water. Simple detoxification techniques might soon be available to remove most of the dopa. “Soaking the powder in room temperature water, even for only two minutes, removes over half of the DOPA. A second two minute soak removed another 29%. 80% is removed in two short soaking periods.” Soaking 5 - 10 minutes does not remove additional dopa.
Using 50°C water is no more effective than water at room temperature. However, soaking 5 minutes in boiling water removed 89% of the dopa and repeating the soak removed 99%.
Dr. Buckles sent Rolf velvet beans from a community in Ghana where people regularly eat velvet beans. Might these be extra low in dopa? Surprisingly, they had even more dopa than some others. Rolf suspected that they are detoxifying the beans and requested details of food preparation methods.
“We now understand how the Ghanians remove the dopa. They boil the beans 45 - 60 minutes, discard the water, add cool water and let the beans cool, then discard that water. Although our extraction techniques have all been with flour, it does not surprise me that they are removing a significant amount from whole beans by boiling.”
This work began when Rolf requested an ECHO publication called Hunger Related Research Opportunities. These list research projects that could be performed with a modest budget that would benefit peasant farmers.
Can you Help? Rolf is asking whether there might be other needs within our network where an analytical laboratory oriented toward needs of Third world small farmers could be helpful. If there are, he will seek funding to set a lab to provide such needs at minimal cost to our network. He would like to hear your ideas. Write him at Judson College, 1151 North State St., Elgin, IL 60123. Phone 708/6952500 ext. 3740. Email: rmyhrman@JudsonU.edu
ECHO Staff 1995. New Information on the Toxic Substance in Velvet Beans. ECHO Development Notes no. 47