The key to making a perfect espresso has been argued over by generations of coffee snobs. Now a group of scientists say they have the answer and have singled out the secret ingredient – and it comes before the grind even begins.
Researchers have discovered that a dash of water added to coffee beans before the grinding process creates a more consistent and tastier espresso, which they say will help baristas and industrial coffee brewers overcome a major hurdle.
When coffee is ground, the friction between the beans creates electricity, causing particles to lump together in the grinder. The research found that adding water to this process reduces the electricity produced, resulting in less coffee waste and stronger flavours.
The scientists also discovered changes in the way espresso is brewed when combining water with different grinding methods.
Christopher Hendon, an associate professor of chemistry at University of Oregon, said: “Water not only reduces static electricity and therefore reduces mess as you’re grinding, but it can also make a major impact on the intensity of the beverage and, potentially, the ability to access higher concentrations of favourable flavours.”
The study, published in the journal Matter, also explored how electricity affected coffee taste. The researchers joined forces with volcanic experts examining related electrical activity during eruptions – a process that they say is similar to coffee brewing.
Joshua Méndez Harper, an assistant professor of electrical and computer engineering at Portland State University, said: “During an eruption, magma breaks up into little particles that come out of the volcano in this big plume. Those particles are rubbing against each other and charging up to the point of producing lightning.
“In a simplistic way, it’s similar to grinding coffee, where you’re taking these beans and reducing them to fine powder.”
The researchers then measured different types of coffee beans, considering the country of origin and colours of coffee roasts. They also noted the coffee processing methods and factored in whether the coffee was washed, decaffeinated or natural, which was found not to affect the amount of electricity produced.
The researchers’ next step is to crack the code for creating the perfect coffee, they said.
Hendon said: “Now we know what grind settings to use to make reproducible espresso, we can start to try to understand what factors give rise to sensory differences in coffee taste.”