科学美国人60秒 SSS 浓缩咖啡磨得越粗越好（在线收听）

Espresso May Be Better when Ground Coarser

Making a cup of coffee isn’t rocket science. But a new study shows that a background in math and analytical chemistry doesn’t hurt. Because researchers who applied their skills in materials science and modeling to brewing espresso have made a grounds-breaking discovery: contrary to popular belief, using fewer beans and a coarser grind will give you a more consistent shot. Their work appears in the journal Matter.

煮一杯咖啡并不难。但一项新的研究表明，拥有数学和分析化学背景对煮咖啡并没有坏处。因为研究人员将他们在材料科学和建模方面的技能应用到煮意式浓缩咖啡上，有了一个突破性的发现:与人们普遍认为的相反，用更少的豆子和更粗糙的研磨会让你得到更好的效果。他们的研究发表在《Matter》杂志上。

If you’re a coffee aficionado, you’ve no doubt noticed that some days, you may get a great espresso; other days, not so much. Even with the same coffee, the same machine, the same settings.

如果你是一个咖啡爱好者，一定注意到了，有时候会喝到一杯很棒的意式浓缩咖啡，但有时候味道确不尽如意。即使是用同样的咖啡，同样的机器，同样的设置。

To understand that variability, the researchers developed a mathematical model to explore how coffee is extracted or dissolved as water passes through the bed of grounds.

为了理解这种变化，研究人员开发了一个数学模型，以探索当水通过咖啡渣层时，咖啡是如何被提取或溶解的。

“Basically, what we did was to start by writing down some equations, which apply to just a single ground.”

“基本上，我们所做的就是从写下一些方程开始，而这些方程只适用于单一领域。”

Jamie Foster, a senior lecturer in mathematics and physics at the University of Portsmouth.

杰米·福斯特是朴茨茅斯大学数学和物理的高级讲师。

“So it’s a less intimidating task, because in a real coffee bed, you’ve got millions and millions of particles that are packed together in this very complicated way. And so a more tractable problem is to write down the equations on a single ground.”

所以这并不是一个吓人的任务，因为在一个真正的咖啡床里，你有成千上万的粒子以非常复杂的方式聚集在一起。所以把方程式逐一写下来是一项更加简单的任务。

To model the entire coffee bed, Foster and his colleagues copied that equation millions of times, stirred in a bit more math and then poured on the theoretical water.

为了建立整个咖啡床的模型，福斯特和他的同事们将这个方程复制了数百万次，再加入一些数学运算，然后将理论上所需的水倒进去。

“The model tells us what we should expect in an ideal situation when all of the coffee is being contacted by all of the water equally.”

“这个模型告诉我们，在理想情况下，当所有的咖啡颗粒都被可以与水均匀接触时，我们应该期待什么。”

Christopher Hendon, a computational chemist at the University of Oregon, who also took part in the study.

俄勒冈大学的计算化学家克里斯多夫·亨顿也参与了这项研究。

“And indeed, the model describes reality very well for particular grind settings, where there is a sufficient amount of large particles so the water can flow freely through that bed. But when you grind sufficiently fine, that’s when we started to see, in real life, a divergence from the expectation that the model was telling us.”

“事实上，该模型非常好地描述了现实的特定研磨设置，有足够数量的大颗粒，水可以自由地流过研磨床。但当你磨得足够细的时候，那就是我们开始在现实生活中看到的，以及模型我们期望从模型中看到产生分歧的时候。

With the fine grind, some shots were stronger than predicted. But some were considerably weaker, which flies in the face of conventional wisdom.

在精细的研磨下，一些研磨比预期的更有力。但有些则弱得多，这与传统观念背道而驰。

“The thinking, if you want a stronger cup of coffee, is, well, I’ll grind it finer, because by doing that, I’ll have smaller particles in my grounds, and the smaller particles will have a higher surface area. And so this high surface area allows for more rapid extraction from the grains”

我的想法是，如果你想要一杯味道更浓的咖啡，那就把它磨得更细，因为这样一来，我的咖啡渣里就会有更小的颗粒，而小颗粒的表面积也会更大。”因此，这种高表面积使得从谷物中提取更迅速"

But what the researchers found is ...

但研究人员发现……

“If you kind of overdo the grinding, what ends up happening is: the particles are so small, in fact, that they kind of clog up the gaps where the water’s trying to flow. And that actually hampers the extraction rather than helping it.”

“如果研磨过度，最终的结果是:这些颗粒非常小，实际上，它们会堵塞水试图流动的缝隙。这实际上阻碍了提取，而不是帮助提取。”

And the same is true for the amount of coffee you start with—so that less can, counterintuitively, end up tasting like more.

同样的道理也适用于你刚开始喝的咖啡量，所以喝得少反而会让你喝得更多。

“Since this article came out, there has been a tremendous amount of activity on Twitter—arguing, discussing, just general excitement and interest in the project. And independent of whether this helps make more reproducible coffee or not, this is a tremendous success—that we have got millions of people to have read a scientific article and engage with science. That’s a great success for scientific literacy.”

“自从这篇文章发表以来，twitter上已经出现了大量的活动——争论、讨论，只是对这个项目普遍的兴奋和兴趣。不管这是否有助于生产更多可再生的咖啡，这是一个巨大的成功——我们已经让数百万人阅读了一篇科学文章，并参与到科学中来。这是科学素养的巨大成功。”

And we can all drink to that.

我们都可以为此干杯。