How to brew the perfect cup of coffee - according to science
Brewing the perfect cup of coffee may seem like an art, but it turns out it’s also a science.
According to findings from a team of mathematicians, physicists and material experts from around the world, fewer coffee beans ground more coarsely are the key to a drink that is cheaper to make, more consistent shot-to-shot, and just as strong.
The results, published in the journal Matter, were the outcome of research from Australia, the US, Britain, Ireland and Switzerland.
The researchers put together a mathematical model to explain the extraction yield based on the factors under a barista’s control, such as the masses of water and dry coffee, the fineness or coarseness of the grounds, and the water pressure.
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They discovered that, although the norm for brewing an espresso shot is to grind a relatively big amount of coffee beans (20 grams) almost as finely as possible, this ended up clogging the coffee bed reducing extraction yield, wasted raw material, and reduced taste consistency by sampling some grounds and missing others entirely.
Much number crunching and thousands of shots later, the team reached a recipe to simultaneously maximise extraction and produce espresso that would taste similar from one cup to the next.
The secret — grinding coarser and using a little less water, while also reducing the mass of coffee.
The researchers stressed, however, that there was “no obvious optimal espresso point”.