Fewer Coffee Beans Ground Coarsely Brews the Best Espresso

    Researchers at the University of Portsmouth set out to see why two cups of espresso brewed the same tasted differently. A team of mathematicians, physicists and materials experts at this university found the secret to the best cup of espresso lies in the number of coffee beans and how they are ground.

    Fewer coffee beans ground more coarsely is the answer!

    According to the researchers which included Dr Jamie Foster, a mathematician at the university, fewer coffee beans and grinding them more coarsely is the secret.

    The researchers started with the question many espresso drinkers have: 

    Two Espresso Shots

    “Why do two shots of espresso made the same way, taste different?”


    They applied mathematical theory to the question and when they began to look at a single grain, many of which create the coffee bed found in the basket of the filter holder, they found the answer. It's more reliable from one cup to the next, if fewer beans ground coarsely.

    When coffee beans were ground finely, the particles were so small that in some places of the filter basket, they clogged up the space where the water should be flowing. These clogged sections of the filter basket are wasted because the water cannot flow through them and access that tasty coffee that's wanted in the cup. If the grind is a bit coarser, the whole filter basket is accessed for a more efficient  extraction.

    Researchers can save the industry money

    An efficient extraction is cheaper because when the grind setting is changed, fewer beans are used. Once the researchers found a way to make espresso shots efficiently, they realised that as well as making espresso shots that stayed reliably the same, they were also using less coffee beans.

    They theory is being tested in a small coffee shop located in the US. The researchers found over a year, this coffee shop saved thousands of dollars using fewer coffee beans. The researchers noted the entire US coffee market could save $1.1 billion a year if they followed their research recommendations.

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