THE most expensive coffee in the world is ***. That is not an opinion, it is a fact. To make Kopi Luwak you must, of course, start with high-quality beans. But then you have to feed them to palm civets, wait while they pass through the animals' guts (having their fleshy exteriors digested as they go) and be ready to collect them when they come out of the other end. The result, when cleaned, fermented, dried, roasted, ground and brewed, sells for as much as $80 a cup. The reason for this apparently ludicrous price is the sublime effect on the beans' flavour of the chemical reactions they undergo in a civet's stomach.Given that price, a lot of counterfeit and adulterated Kopi Luwak gets peddled as the real thing. And until now there has been no reliable way to detect it. A purchaser may think from the flavour that he has been duped, but he cannot prove it.
Eiichiro Fukusaki of Osaka University, in Japan, plans to change that. As he describes in the Journal of Agricultural and Food Chemistry, he and his colleagues in Japan and Indonesia have developed a chemical test which, they believe, can reliably detect essence of civet in coffee.
Dr Fukusaki's quest began with many piles of civet faeces, as well as undigested coffee beans from plantations in Bali, Java and Sumatra, all of which he treated by roasting them at 205°C and then grinding them up. Instead of popping them into a percolator at this point, though, he mixed them with distilled water, methanol and chloroform to extract the sorts of chemicals that give coffee its flavour. He then ran the extracts through a gas chromatograph and a mass spectrometer, to see what was in them.
The crucial giveaways of Kopi Luwak turned out to be four substances: citric acid, malic acid, pyroglutamic acid and inositol. The real McCoy had much more of the first two than similar beans that had not undergone trial by civet, and the ratio of the last two was reliably different. Moreover, the differences were big enough that even a 50:50 mixture could be identified, enabling adulterated Kopi Luwak, as well as stuff masquerading as it, to be detected.
Whether lower levels of adulteration than that can be detected remains to be seen. But Dr Fukusaki's method, if widely adopted, would certainly weed out the worst excesses of the fraudulent Kopi Luwak market. On the other hand, it might inspire counterfeiters to try tweaking their products with laboratory chemicals. And if that resulted in the same flavour as the genuine article it would relieve the civets of their onerous task and open up the drinking of Kopi Luwak to mere mortals.世界上最昂贵的咖啡是——屎。这并非一种观点，而是事实。要制作努瓦可咖啡，首先，你当然需要质量上乘的咖啡豆。之后，你就得把豆子喂给狸猫吃，等它们穿过狸猫的消化道（消化掉其肉质般的果皮），你就可以着手准备从另一端的“出口”采集成品了。经过清洗、发酵、干燥、烘烤，研磨和冲泡后，一杯价值高达80美元的咖啡就做成了。这样近似荒谬的价格，是由于咖啡豆在狸猫的肚子里经历过一系列化学反应后，其香味得到了极大的提升。
由于价格不菲，市场上许多假冒伪劣的咖啡冒充努瓦可咖啡进行兜售。直到现在，也没能出现一种可靠的鉴别方式。消费者也许从味道上感觉到自己可能被欺骗了，但却无法证实。
日本大阪大学的福崎荣一郎打算改变这一现状。他在《农业与食品化学期刊》上写道，他与来自日本和印尼的同事一道，发明了一种化学测试方法。他们坚信，这种测试方法能够准确地检测出咖啡中的狸猫“要素”。
福崎博士的探索以一堆堆狸猫的粪便开始，同时还有来自巴厘岛、爪哇岛和苏门答腊岛上种植园里未经消化过的咖啡豆。所有这些豆子都被福崎博士用205°C的高温对其进行烘焙，然后再将其研磨。这时，他并不急着把咖啡粉倒进咖啡壶里，而是将其与蒸馏水、甲醇和氯仿混合在一起，用来提炼出赋予咖啡香味的各种化学物质。然后，他通过气相色谱仪和质谱仪来观察提炼物，看看里面究竟是些什么。
结果显示，判断努瓦可咖啡真伪有四要素：柠檬酸、苹果酸、焦谷氨酸以及肌糖。货真价实的努瓦可咖啡，其前两种要素的含量要明显高于同类的未经狸猫消化过的咖啡豆。后两种要素的比例也有所不同。而且，这种差别很大，甚至连１比１混合过的咖啡都能被识别出来。这使得人们有能力检测出假冒的和掺假的努瓦可咖啡。
微量的掺假是否也能被检测出来目前尚未可知。但是福崎博士的方法一旦被广泛采用，定将清除假冒伪劣的努瓦可咖啡在市场上猖獗的现状。另一方面，这可能会激发造假者对其产品进行调整，改用实验室化学物质。如果最后得到了与正品相同的味道，那它将解放狸猫们繁重的＂任务＂，也为普通老百姓能喝上努瓦可咖啡带来了希望。
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