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【科普】烘焙咖啡到底有没有抗氧化作用？
Roasting Coffee Beans a Dark Brown Produces Valued Antioxidants, Scientists Find
ScienceDaily (Feb. 3, 2011) — Food scientists at the University of British Columbia have been able to pinpoint more of the complex chemistry behind coffee's much touted antioxidant benefits, tracing valuable compounds to the roasting process.
Lead author Yazheng Liu and co-author Prof. David Kitts found that the prevailing antioxidants present in dark roasted coffee brew extracts result from the green beans being browned under high temperatures.
Their findings will appear in a forthcoming issue of Food Research International.
Liu and Kitts analyzed the complex mixture of chemical compounds produced during the bean's browning process, called the "Maillard reaction." The term refers to the work by French chemist Louis-Camille Maillard who in the 1900s looked at how heat affects the carbohydrates, sugars and proteins in food, such as when grilling steaks or toasting bread.
Antioxidants aid in removing free radicals, the end products of metabolism which have been linked to the aging process.
"Previous studies suggested that antioxidants in coffee could be traced to caffeine or the chlorogenic acid found in green coffee beans, but our results clearly show that the Maillard reaction is the main source of antioxidants," says Liu, an MSc student in the Faculty of Land and Food Systems (LFS).
"We found, for example, that coffee beans lose 90 per cent of their chlorogenic acid during the roasting process," says Kitts, LFS food science professor and director of the Food, Nutrition and Health program.
The UBC study sheds light on an area of research that has yielded largely inconsistent findings. While some scientists report increased antioxidant activity in coffee made from dark roasted beans, others found a decrease. Yet other theories insist that medium roast coffees yield the highest level of antioxidant activity.
Researchers have found that the prevailing antioxidants present in dark roasted coffee brew extracts result from the green beans being browned under high temperatures. (Credit: iStockphoto/Olga Milkina) 【科普】24种保护心脏的食物(已译,图文并茂!) - 医药生命科学动...发表时间：2010-3-19回帖数：14http://www.webmd.com/heart-disease/slideshow-foods-to-save-your-heart slideshow: 24 ... 同时需要注意,对于那些已经有糖尿病或高血压的患者,咖啡因具有复杂的作用. 贴士: 选...www.ruanjian520.com/thread-... - 2010-03-19-快照-【科普】24种保护心脏的食物(已译,图文并茂!) - 医药生命科学动..." 大洋新闻 - 滚动频道2010年8月24日... 林文漪:台湾农民创业园为两岸农业合作发挥作用 网易彩票推介法国联赛杯:阿些... 市发改委积极服务项目建设 中关村生命科学园吸引项目总投资逾百亿元 四川绵...www.dayoo.com/...4/index.shtml-2010-08-24-快照-益农视窗零售商在快速消费品企业最终产品的销售中将会发生越来大的作用,他们比供应商同消费者... 《畜牧与饲料科学》《饲料世界《粮食与饲料工业》《兽药与饲料添加剂》《中国动物检...www.cn99.com/...me=ynsc&id=106-2005-10-14-快照-[标签:content2]
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作者:admin@医学,生命科学 2011-02-05 14:58
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