Want stronger coffee with fewer beans? Pour from high up, study says

Those hoping to have a strong cup of coffee with fewer beans should pour water from high up, says a new study.

Researchers from the University of Pennsylvania wanted to test how to make a great cup of one of the world’s most popular drinks. In a research article published in April in the scientific journal Physics of Fluids, they wrote that “issues such as climate change threaten the growth of the temperature-sensitive Coffea arabica plant, more commonly known as Arabica coffee.”

The researchers wanted to find a way to become more efficient brewers, “using less coffee while still meeting the high demand for the beverage.” They decided on the pour-over method, which involves pouring hot water over coffee grounds in a paper filter that sits in a coffee dripper, or cone. The cone is placed over a vessel that catches the liquid — coffee — that has gone through the filter. “This brewing method primarily uses gravity to push water a single time through coarse, loosely packed coffee grounds,” the researchers explained.

They used Simply Nature Organic Honduras whole coffee beans, and ground them with a Eureka brand grinder.

One of the researchers, Ernest Park, told National Post over email that the team tested pouring water from up to around 50 centimetres above the filter. However, he said that people can realistically pour from about 20 to 25 centimetres above the filter, with a maximum of around 30 centimetres, because it can start to “get a bit dangerous with hot water” if it’s poured from too high up.

The researchers first did tests using silica gel particles (to mimic the coffee grounds), a glass filter that they could see through, a laser sheet and a high-speed camera. They discovered “an avalanche effect (where granules suddenly slide and form large-scale flows) that leads to strong mixing at various pour heights, even with a gentle pour-over jet” — or a thin stream of water. To achieve a gentle pour-over jet, the team used a gooseneck kettle.

Next, they tested the coffee grounds with hot water.

Increasing the height between the kettle used for pouring and the cone ended up maximizing the mixing of the grounds with water. It also reduced the flow rate of the water to increase extraction time. (As it pertains to coffee, extraction refers to when compounds like caffeine are pulled from the grounds when they are mixed with hot water.)

The findings suggest, per the researchers, that “instead of increasing the amount of beans, the sensory profile and the strength of the beverage can be adjusted by varying the flow rate and the pour height.”

Researchers recommend keeping a laminar water jet, or constant flow of water, when pouring. This allows the stream to create the avalanche effect.

“These alterations assist in extracting and dispersing the flavourful compounds in coffee grounds effectively while reducing the necessary mass of grounds,” the paper says. “In this way, the extraction efficiency could be better controlled to help alleviate the demand on coffee beans worldwide.”

The publication of the paper comes at a time when tariffs have been imposed by U.S. President Donald Trump on countries around the world, including some of the biggest producers of coffee. Globally, coffee prices surged to record highs in January.