How you pour coffee changes its strength and flavor

Coffee is more than just a drink. It’s a daily ritual, a cultural symbol, and for many, a necessity. We pour it in the morning to wake up, share it with friends to connect, and rely on it through long work hours. Globally, people consume tens of billions of kilograms of coffee each year.

Yet, this love for coffee faces serious challenges. Coffee grows in narrow climate zones and depends on very specific conditions. As climate change disrupts weather and soil patterns, it threatens the future of this cherished crop.

To meet rising demand without increasing the pressure on production, scientists are turning to an unexpected solution: the physics of brewing.

A recent study from the University of Pennsylvania offers insights on how changing how we pour coffee could improve its quality and reduce waste.

Pour height changes coffee strength

The team explored one of the most beloved brewing methods – pour-over coffee. The researchers focused not on coffee chemistry, but on how water interacts with coffee grounds. They aimed to find a better way to extract more flavor from fewer beans.

“What we recommend is making the pour height as high as possible, while still maintaining a laminar flow, where the jet doesn’t break up when it impacts the coffee grinds,” said Ernest Park, the study’s lead author.

This may seem like a small detail, but the study revealed it’s significance. By carefully adjusting the height and shape of the water stream, the researchers were able to improve the entire brewing process.

Water poured from a greater height with steady flow digs into the coffee bed more effectively, stirring up the grounds.

Why jet strength matters

The researchers found that gooseneck kettles – a favorite among coffee lovers – produce the ideal kind of stream.

These kettles create a thick, focused jet that avoids splashing or breaking into droplets. When this strong stream hits the coffee bed, it creates a controlled avalanche of motion. The grounds rise and fall in a wave-like pattern, allowing deeper mixing.

This movement improves the interaction between water and coffee. The deeper the water penetrates and stirs, the more flavor it pulls out. As a result, stronger coffee can be made using fewer grounds, a win for both taste and sustainability.

“If you have a thin jet, then it tends to break up into droplets,” said co-author Margot Young from the University of Pennsylvania.

“That’s what you want to avoid in these pour-overs, because that means the jet cannot mix the coffee grounds effectively.”

Thin jets lose their shape before they reach the coffee bed. This weak flow lacks the power to stir the grounds properly. Without movement, much of the flavor stays trapped in the unused layers.

Shining a light on coffee pour and flow

One challenge in studying coffee is that it’s naturally dark. You can’t see how water moves through the grounds during brewing. To solve this, the team turned to a creative method.

The experts used transparent particles instead of actual coffee and placed them in a clear glass funnel. Then, they illuminated the setup with lasers to track the motion of the water.

This allowed the researchers to directly observe how different streams affected the mixing. They saw how laminar jets dug into the grounds, circulated particles, and created whirlpool-like patterns.

The trial confirmed what the pour-over experiments suggested: stronger, steady jets produce better mixing and more complete extraction.

Pouring trick to make stronger coffee

The researchers don’t plan to continue with coffee-specific studies, but they believe this work opens the door for more everyday science.

There are still many brewing factors to explore – grind size, temperature, pouring technique – that shape the final cup. These are not just culinary questions but scientific ones too.

“We can really learn something from both the chemistry and physics point of view by looking at the kitchen,” said co-author Arnold Mathijssen. “It leads to new science where you didn’t expect it.”

The researchers’ advice? Try it at home.

Pour your coffee from a higher point, using a thick, steady stream. Watch the results. You might get a stronger, smoother brew – without needing more beans.

Sometimes, even in something as ordinary as a morning cup of coffee, physics has the final word.

The study is published in the journal Physics of Fluids.

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