Science has shed light on a long-debated coffee question: What’s the best way to make an espresso? A collaboration between a coffee expert and a volcanologist aims to provide new insights.
This topic has sparked countless discussions and YouTube videos, but the study offers a fresh perspective on the matter.
Christopher Hendon, a materials chemistry researcher at the University of Oregon, emphasized the importance of efficiency in coffee production. He explained that increasing coffee concentration by 10% to 15%, using the same amount of beans, could reduce costs while improving quality.
Static electricity and coffee grinding
The grinding process generates static electricity through triboelectrification, which can make cleaning grinders challenging. Until recently, how this static buildup affected the final brew was unclear.
Interestingly, a similar static charge occurs during volcanic eruptions. Volcanologist Joshua Mendez Harper explained that when magma breaks into fine particles during an eruption, the particles rub together, building up charge and sometimes creating lightning.
In a simplified comparison, grinding coffee is similar. “You take beans and turn them into fine powder,” Harper said.
Hendon, Mendez Harper, and their team began by measuring static electricity from different coffee beans. They analyzed factors such as roast level, caffeine content, country of origin, and moisture levels.
Their findings showed that coffee with higher moisture content and a coarser grind generated less static electricity. Lighter roasts, which tend to be less dry, produced more positive charge but overall less static than darker roasts, according to IFL Science.
Making espresso with and without a splash of water
Recognizing the importance of moisture content, the research team explored whether adding water could improve coffee grinding. They conducted tests by brewing espresso with the same beans, comparing shots with and without a small splash of water—a technique sometimes used by baristas.
Adding up to 20 microliters of water per gram of coffee not only made each shot more consistent but also extended extraction time, resulting in a stronger brew.
According to Christopher Hendon, adding water during grinding offers a significant advantage. It prevents clumping, allowing for denser packing of the coffee bed, which improves the overall process.
This improvement is especially noticeable in espresso, where clumping is a common issue. The benefits can also be seen in brewing methods that involve pouring water over coffee or in smaller percolation systems like stovetop Bialettis.
However, methods such as the French press, which involve submerging coffee in water, won’t experience the same advantages, Hendon noted.
Colombian coffee is ideal for espresso
Colombian coffee is reknown for its high quality and unique flavor profile, largely due to the country’s ideal coffee-growing conditions, including its rich volcanic soil and diverse climate. Known for producing predominantly Arabica beans, Colombian coffee offers a well-balanced, mild flavor with bright acidity and notes of caramel, nuts, and fruit.
These attributes make Colombian coffee a great choice for espresso preparation, where its sweet, rich flavor and smooth finish shine.
Medium to dark roasts are particularly well-suited for espresso as they bring out the rich flavors and help create a good crema. Proper grinding is essential for espresso, with a fine grind resembling table salt ensuring optimal extraction. Brewing temperatures should range between 90-96°C (194-205°F), with an extraction time of 25-30 seconds for the best results.
The versatility of Colombian coffee allows it to work well in both straight espresso shots and milk-based drinks like lattes and cappuccinos.