Technology: Americans move from potato peel to supermarket . . . and back into the soil

日期:2019-02-28 03:02:07 作者:裘冷畏 阅读:

By ANDY COGHLAN HUMBLE potato peelings and cheese waste could one day provide a cheap and practicable raw material for making carrier bags that decay in sunlight or soil. The idea comes from the US, where liquid discharges from potato processing factories and from cheese plants provide a plentiful source of starting materials. Researchers at the Argonne National Laboratory in Illinois, part of the University of Chicago, have already succeeded in isolating from potato waste a material for making biodegradable plastic. The material, lactic acid, is available at present and even exists naturally in our muscles, but production of biodegradable polymers from natural sources of the acid – such as corn starch – is impracticably expensive. The only uses for the polymers currently available from lactic acid are as sutures for internal surgery – stitches that dissolve over time in internal wounds and incisions. The use is exclusive and profitable enough to justify the cost of making lactic acid from corn starch, which costs about 12 US cents per pound. Robert Coleman and colleagues at Argonne have perfected a way of producing the same material 12 times as cheaply from carbohydrates in waste from factories where uncooked chips are made. Normally, the waste is sold as cattle feed for, at most, $6 a tonne. Coleman says that Argonne hopes within the next two or three years to develop technology for producing custom-built grades of polylactic acid that could biodegrade or photodegrade (or both) depending on the application. So far, Coleman and colleagues have succeeded in speeding up from 100 hours to 6 hours the process of breaking down carbohydrates in potato waste to glucose, the sugar that rapidly ferments to form lactic acid. Now, Patrick Bonignore, a colleague at Argonne, is working on the technology to make lactic acid into plastics which meet specific needs. There are many potential applications for a genuinely biodegradable plastic. These range from slow-release drugs and pesticides to plastic carrier bags and mulch sheets – stretches of plastic laid over crops to prevent weeds and frost from damaging crops. Holes in the sheets allow the crops and nothing else to penetrate through. Coleman and his colleagues at Argonne want to develop sheets that decompose once the crop is finished. The researchers have filed proprietary ‘invention reports’ to the US Patent Office to protect their technology. They expectthe processes they have developed forisolating glucose from potato waste to beequally as effective with cheese waste – or, whey – and other effluents containingcarbohydrates. Two companies have already expressed interest in taking out a licence on the technology. One is Land O’Lakes of Minneapolis, a company that is possibly the largest producer of dairy products in America. The other company is Procter & Gamble of Ohio, the highly diversified soap and detergent company. The researchers at Argonne aim to perfect an entire system which converts the waste into plastic,