Coffee, one of the world’s most beloved beverages, has recently become significantly more expensive, prompting consumers to rethink how they brew their daily cup.
Physicists have now discovered a way to make a stronger coffee using less ground coffee when brewing filter coffee by hand.
Filter coffee is reportedly one of the most popular ways to enjoy coffee - prepared with a machine or manually with a porcelain or plastic filter lined with special filter paper.
Brewing smarter: the science of pour-over coffee
Filter coffee remains one of the most popular ways to enjoy coffee, whether prepared with a machine or manually using a porcelain or plastic filter lined with special paper.
The manual pour-over method, which involves slowly pouring hot water over freshly ground coffee in a circular motion, has seen a resurgence in popularity in recent years.
Researchers writing in the journal Physics of Fluids explain that the key to maximizing flavour lies in the height and flow of the water stream.
Using a swan-neck kettle, which allows for precise pouring, creates a strong, concentrated jet of water that stirs the coffee grounds.
This motion, described as an "avalanche effect," circulates the grounds and allows the water to penetrate deeper into the coffee bed, resulting in a stronger, more flavourful brew.
"If you have a thin jet, then it tends to break up into droplets," explains co-author Margot Young from the University of Pennsylvania.
The research team used laser-illuminated particles in a glass funnel to study the mixing dynamics, turning their kitchen into a research lab.
Co-author Arnold Mathijssen from the University of Pennsylvania points out that you can generally learn a lot about physics and chemistry in the kitchen. "It leads to new science where you didn't expect it."
Coffee: A billion-dollar global commodity
Coffee is not just a morning ritual - it’s a global economic powerhouse. According to the British Coffee Association, about 2 billion cups are consumed daily worldwide.
Expert in coffee trade economics, José G. Vargas-Hernández, says that "coffee is the second most consumed beverage globally after water, in the same way it is the second most exported product after oil."
The coffee trade generates billions of dollars annually and is a vital source of income for many countries.
Every year, several billion kilograms of coffee are consumed worldwide, the US umbrella organization of physical societies AIP reports.
However, the industry faces growing challenges. Climate change is threatening coffee cultivation, with extreme weather events and rising temperatures reducing suitable growing areas and causing crop failures.
At the same time, global demand for coffee is increasing, particularly in Asia, driving prices even higher. – dpa
