WE ALL know what beans means. But now there鈥檚 a way to eat bean-filled food like curries and salads with far fewer episodes of flatulence. Food scientists in India have discovered that blasting some beans with gamma rays can help oust most of the chemicals that make people fart.
Bacteria in the large intestine produce the accumulation of gas that causes flatulence. When these bugs consume certain types of carbohydrates, called oligosaccharides, they produce a mix of gases that includes methane and certain sulphur-containing gases. It鈥檚 the latter that have people pinching their noses.
On average, adults produce 4 to 5 litres of gas a day, and beans are the vegetables most commonly associated with excess wind. That鈥檚 because up to 60 per cent of their carbohydrates are oligosaccharides.
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So Jammala Machaiah and Mrinal Pednekar in the food-science lab at the Bhabha Atomic Research Centre in Trombay, India, decided to see what effect radiation might have on the levels of these carbohydrates in various pulses common in the Indian diet, including mung beans, chickpeas, black-eyed beans and red kidney beans.
Using standard food irradiation technology, they irradiated some samples of each with a low-intensity gamma-ray beam, and other samples with a beam three times as strong. They then gave the beans the typical two-day soaking in cold water that people use before cooking the beans.
The researchers report in a paper to be published in the journal Food Chemistry that the initial irradiation slightly reduced levels of oligosaccharides. But the further reduction that occurs naturally with soaking was dramatically accelerated in the irradiated beans, especially black-eyed beans. After two days鈥� soaking, the low dosage of radiation reduced oligosaccharides in mung beans by 70 per cent, and the high dose by 80 per cent, compared with a drop of only 35 per cent in soaked beans that had not been irradiated. Black-eyed beans and chickpeas also showed a marked improvement. Only kidney beans remained unaffected by the treatment, but they have only a fraction of the guilty oligosaccharides anyway.
鈥淚n India, beans are a very popular and important part of the national diet, but some people can鈥檛 eat a lot of beans because of the flatulence problem,鈥� says Machaiah. 鈥淭his is unfortunate, as it is a very good source of essential nutrients. Irradiation would make beans less of a problem.鈥�
In Europe, food can only be irradiated under licence, and the treated food has to be marked. Irradiation extends the shelf life of herbs and spices by killing the bacteria that make them rot.
Oligosaccharides are 鈥渁nti-nutritional factors鈥�, says Stephen Cole, technical director of Enzyme Services and Consultancy in Blackwood, Wales. 鈥淚f irradiation helps reduce them that鈥檚 good.鈥� Cole鈥檚 company is currently analysing enzymes that break down oligosaccharides in animal feed to prevent pigs or chickens becoming bloated.
But Glenn Gibson, a food microbiologist at Reading University, is concerned that reducing the level of oligosaccharides in the food may have undesirable effects. 鈥淔latulence is an important indicator of a healthy gut system,鈥� he says. 鈥淚t鈥檚 only a social problem. You need to expel gas to ensure your gut is functioning properly.鈥� The gases that cause it could be of benefit, and we should all just learn to live with it, he says.