Taking the wind out of eating beans

A blast of gamma rays can quell the ill-wind that accompanies eating beans, it was reported.

Food scientists in India have discovered that irradiating beans can rid them of the chemicals that cause flatulence.

The embarrassing symptom is caused by bacteria in the large intestine reacting to certain types of carbohydrate called oligosaccharides.

A mix of gases is produced by the bugs that include methane and sulphurous compounds.

On average, adults produce four to five litres of gas a day. Beans are most commonly associated with the problem because up to 60% of their carbohydrates are oligosaccharides.

Jammala Machaiah and Mrinal Pednekaar, at the Bhabha Atomic Research Centre in Trombay, investigated the effect of radiation on mung beans, chickpeas, black-eyed beans and red kidney beans.

Samples of each were bombarded with gamma radiation. The beans were then given the typical two-day soaking in cold water that is necessary before they are cooked.

The researchers found that initial irradiation slightly reduced levels of oligosaccharides. But the further reduction that occurs naturally with soaking was dramatically increased in gamma-exposed beans.

Low dosage radiation reduced the chemicals in mung beans by 70% while a high dose lowered levels by 80%.

This compared with a drop of only 35% in soaked beans that had not been irradiated.

Black-eyed beans and chickpeas also showed a marked improvement, New Scientist magazine reported today.

Only kidney beans appeared to remain unaffected - but they only contain small amounts of oligosaccharides anyway.

Machaiah said: "In India, beans are a very popular and important part of the national diet, but people can't eat a lot of beans because of the flatulence problem. This is unfortunate, as it is a very good source of essential nutrients.

Irradiation would make beans less of a problem."

Food in Europe can only be irradiated under licence and has to be marked after treatment. Irradiation extends the shelf life of herbs and spices by killing bacteria.

However Glenn Gibson, a food microbiologist at Reading University, is not convinced that windless beans would be a good thing.

"Flatulence is an important indicator of a healthy gut system," he told New Scientist. "It's only a social problem. You need to expel gas to ensure your gut is functioning properly."

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