Coffee connoisseurs have long held the belief that adding a little water to the beans before grinding them could make a difference. A new study by researchers at the University of Oregon seems to confirm exactly why. The research explored how the technique, which started as an attempt to address the often messy coffee-making process, also affected flavor. “When you grind coffee, it goes everywhere,” said study coauthor Christopher Hendon, an associate professor of computational materials chemistry at the University of Oregon. “Dust comes out of the grinder, it’s like a plume that covers everything. But if you add a little water, it seems to not go everywhere. It’s cleaner. That was the primary reason people did it.” The mess is caused by static electricity, which is created by friction when the beans are smashed together. This static charge then makes the particles of ground coffee repel each other — like magnets of the same polarity — sending them off in every direction. Water acts like an insulator, dampening this effect — a process known as the “Ross droplet” technique. “It was first proposed by some enthusiast on a home barista forum,” Hendon said. “The idea has been around for several years, and originally it was borrowed from the materials production industry, like wood pulping.” However, what started out as a way to reduce mess slowly morphed into a more sophisticated way to obtain a better brew — or at least so people thought. The theory was that by reducing static electricity, water not only kept the ground coffee from flying around or sticking to the insides of the grinder, it also prevented microscopic clumps from forming during brewing. Why are clumps bad? Because water flows around them, leaving untouched coffee — and therefore flavor — behind. In barista parlance, they decrease extraction yield, or the amount of coffee that ends up in the cup, dissolved in the liquid. “If you have clumps forming, there’s going to be significant amounts of void space, kind of like when you stack watermelons,” Hendon said. “As a result when you push water through you end up with less surface area touching the water and therefore lower extraction.” The study, published Dec. 6 in the journal Matter, tested this more subtle, harder to see potential benefit of adding water to the beans: getting rid of flavor-robbing microclumps. Fran?ois Knopes of the Independent Coffee Lab, a professional coffee roaster and taster who was not involved with the study, said he routinely sprays his beans before grinding for tasting evaluation and would recommend doing so to anyone in a home setting. (SD-Agencies) Words to Learn 相關(guān)詞匯 【演變成】yǎnbiàn chéng morph into gradually change into 【說法】shuōfǎ parlance a formal word that means a group of words or style of speaking used by a particular group of people 長期以來，咖啡品鑒師們一直認為，在磨豆之前加一點水可以讓咖啡變得與眾不同。俄勒岡大學(xué)研究人員的一項新研究似乎證實了這一點。 研究探討了加水是如何影響咖啡風(fēng)味的，這種方法起初是為了解決咖啡制作過程中粉末亂飛的問題。 這項研究的共同作者、俄勒岡大學(xué)計算材料學(xué)副教授克里斯托弗?亨登說：“研磨咖啡時，咖啡粉會到處飛。粉塵從研磨機里出來，弄得到處都是。但如果你加一點水，粉塵不會四處飛散，就更干凈了。這是人們磨豆之前加水的主要原因。” 這是由靜電造成的，豆子一起摩擦?xí)r產(chǎn)生靜電，讓咖啡粉顆粒像極性相同的磁鐵一樣相互排斥，向各個方向散開。 水把咖啡豆包裹起來，可以抑制這種效應(yīng) —— 這被稱為“羅斯液滴”技術(shù)。亨登說：“最早是某個咖啡愛好者在家庭咖啡師論壇上提到這種做法。它已經(jīng)存在好幾年了，最初是從材料生產(chǎn)行業(yè)借鑒過來的，比如木材制漿。” 起初只是防止粉末飛散，后來慢慢演變成了一道用來獲得更好的沖泡效果的工序 —— 至少大家這么認為。當時的理論是，通過減少靜電，水不僅能防止咖啡粉四處飛散或粘在磨豆機內(nèi)部，還能防止咖啡在沖泡過程中形成微小的結(jié)塊。 結(jié)塊為什么不好？因為水從它們周圍流過，部分咖啡沒接觸到水，味道也就沒出來。用咖啡師的話來說，結(jié)塊會降低萃取率，即最終留在杯中溶解在液體中的咖啡量。 亨登說：“如果咖啡結(jié)塊，就會產(chǎn)生大量的空隙，就像把西瓜疊在一起。因此，當你把水壓過咖啡粉時，粉末接觸水的表面積減少，從而降低萃取率。” 這項于12月6日發(fā)表在《物質(zhì)》雜志上的研究測試了向咖啡豆中加水更微妙、更難察覺的好處：防止破壞咖啡風(fēng)味的微結(jié)塊。 獨立咖啡實驗室的弗朗索瓦?克諾普斯是一名專業(yè)咖啡烘焙品鑒師，沒有參與這項研究。他說，自己經(jīng)常磨豆前噴點水，以便更好地品鑒咖啡，并建議大家在家里也這樣做。 (Translated by Debra) | 