怎样辨别假威士忌

Whiskey Fraud

我们前些年注意到市面上有很多假威士忌,苏格兰大学环境研究中心的戈登库克说。苏格兰威士忌是苏格兰特产,而我们作为苏格兰的一家放射性碳实验室,深感责任在肩。苏格兰威士忌的原料是大麦,大麦生长过程中会吸收空气中的二氧化碳,大多数是碳十二,有很小一部分是放射性同位素碳十四。碳十四会以恒定的已知速率衰变,因此一直又被用来作为碳测年份的生物学标本。

一九五零年代早期,人类开始在大气中测试核武器,测试核武器就会产生碳十四。一九六零年代,碳十四达到自然界水平的两倍。一九六三年有了禁止核武器测试条约,那年碳十四水平达到峰值。自那以后,随着放射性碳元素进入生物区和海洋,大气中的碳十四水平逐渐降低。所以,如果碳十四水平异常的高,说明大麦生长在人类大范围测试核武器的年代。

威士忌显然还可以用来赚钱,很多人买年代久远的威士忌,并不是买来喝,而是投资。去年十月,拥有六十年历史的一九六二年产威士忌以一百九十万美元的价格拍卖。为了确定这些苏格兰威士忌是否货真价实,库克和同事研究了酒里的碳十四水平。

他们标记了两百多种已知年代纯麦苏格兰威士忌的碳十四水平。然后将八瓶号称一八四七年到一九七八年产威士忌和这些酒的碳十四水平进行对比,结果发现这八瓶酒没有一瓶是真货,因为所有这些所谓的十九世纪威士忌都明显含有核武测试年代才有的物质。这项研究发表在放射性碳杂志上。库克希望这些举证技术能帮助威士忌产业多出真货。就像罗伯特伯恩斯所说,只有酒不会骗我。

原文

“It came to our attention a few years ago that there were fraudulent whiskeys on the market.” Gordon Cook of the Scottish Universities Environmental Research Center. “Scotch whiskey is Scotland’s product, and we felt that being a radiocarbon laboratory in Scotland, we should take a lead on this.” Scotch whiskey is made from barley, which absorbs carbon dioxide from the air as it grows. Most of the carbon is carbon-12. But a small percentage is the radioactive isotope carbon-14, which decays at a constant, known rate— and has therefore long been used to “carbon-date” biological samples.

“Then, in the early 1950s, we had the start of the atmospheric weapons test, and these produce carbon-14. By 1960, you were twice the natural level. And ’63—there was a test ban treaty, so ’63 was the maximum. Since then, the level in the atmosphere has decreased as the radiocarbon goes into the biota and the oceans.” So unusually high levels of carbon-14 are associated with barley grown during the years when nuclear testing was widespread.

There’s obviously a lot of money in whiskey. And some classics get bought not as imbibements but as investments. Last October, a 60-year-old 1926 bottle was auctioned off for $1.9 million. To make sure that the stuff inside bottles of Scotch whiskey matches what’s on the labels, Cook and his colleagues looked at levels of the carbon-14 in the drink.

They calibrated levels of the radioactive variant of carbon in more than 200 different single-malt Scotch whiskey samples of known ages. The researchers then compared those levels to eight whiskeys claiming to have been bottled from 1847 to 1978. “We haven’t found any whiskeys purported to be from the 19th century that are genuine.”Because those allegedly 19th-century bottles contained material clearly produced during the nuclear-testing era. The study is in the journal Radiocarbon. Cook hopes these verification techniques will help keep the whiskey business true to the words of Robert Burns: “Here’s a bottle and an honest friend.”

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