New optimal coffee-making method according to science

Zuyi and Elaine Woon are owners of Pour and Twist, a 'fully manual' coffee bar in Wellington. Photo / Reece Baker, RNZ

By Serena Solomon of RNZ

Scientists have found how to make stronger coffee with the same amount of beans through the pour-over method. We put it to the test.

Scientists have figured out an optimal method to get more out of a coffee bean so that coffee drinkers can either have a stronger brew or use fewer beans for the same taste.

A team of scientists from the University of Pennsylvania in the United States released a study on Wednesday outlining the optimal way to make a pour-over coffee.

It’s a manual method of coffee-making where hot water, often poured slowly from a gooseneck kettle, seeps through coffee grounds and into a cup. Pour-over coffee draws hyper-coffee fans because the method is known to release the individual flavour notes of the beans used, more so than espresso.

According to the study, pouring water from a higher height of no more than 30cm for safety’s sake can make a stronger cup of coffee with the same amount of beans. The added height increases the velocity of the water, which creates an “avalanche” in the coffee grounds and maximum coffee exposure to the hot water.

The study’s findings indicate that pouring slowly - but not too slowly - also plays a role in upping the coffee’s strength as does keeping the stream of water consistent.

The added strength means that coffee makers could drop the amount of ground coffee by 10% while maintaining their usual strength, according to the study.

How does it translate to the real world?

Elaine Woon and her husband Zuyi are the owners of Wellington’s Pour and Twist, a “fully manual” coffee bar focused on brewed filtered coffee, including pour-over coffee. Shockingly, there is no espresso machine.

The Woons have been in business for eight years. In that time, they have perfected the art of pour-over coffee. Depending on the type of bean used and the coffee they are making, they might pour from 10cm or higher, and change the height as they are making it. It all depends on the sight, smell and taste of what is in front of them.

“It is probably a bit of both - science, yes but because we have been brewing for so long it has helped us understand how some beans are compared to others,” says Elaine.

“It is definitely an art.”

The Woons helped RNZ with an experiment - making pour-over coffee as outlined in the study by pouring consistently from a height of 30cm.

“Overall a really fun experiment. It worked for the most part,” Elaine says.

“We used a light-roasted Ethiopian [bean]. There was definitely more body and stronger than what it would turn out if we brewed it normally.”

However, as Elaine predicted, the increased pour height created more agitation when it hit the grinds, increasing the strength - like the study found - but it also messed with the taste.

“I know a lot of people will be okay with the coffee we make with that method just now, but if, like us, you don’t want to sacrifice a well-brewed coffee with balance, acidity, and sweetness, then this method is not for you.

“We got a little bit of bitterness and dryness.”

The Woons said they would stick with their tried and true methods.