BY THE OPTIMIST DAILY EDITORIAL TEAM
So many of us participate in the same morning coffee ritual: the machine warming up, the pressure building, the crema settling into the cup. It’s such a fixed sequence that it’s hard to imagine any part of it changing. But against the odds, researchers at the University of New South Wales in Sydney just changed the most fundamental part.
Their new method brews espresso using ultrasonic soundwaves instead of heat, at room temperature, in under three minutes. In a blind taste test with 100 coffee drinkers, the results were indistinguishable from a traditionally made shot. “It’s a different process, but you get the same richness and concentration of a normal espresso in under three minutes,” said Francisco Trujillo, a chemical engineer and co-author of the study published in the Journal of Food Engineering.
How do soundwaves make espresso?
The process centers on a phenomenon called acoustic cavitation. Researchers fitted a standard filter basket with a transducer, a small metal device that generates ultrasonic vibrations. Those vibrations pass through the coffee grounds and water, causing microscopic bubbles to form and collapse rapidly. Each collapsing bubble acts like a tiny brush against the coffee grounds, breaking them open to release their flavor compounds, caffeine, and oils.
Getting the recipe right took some tinkering. “The most important [part] was the brew ratio, that is how much water is used per gram of coffee, because this helps ensure the final drink is concentrated and not too diluted,” Trujillo explained. The team also worked through variables like grind consistency and the length of exposure to the soundwaves before landing on the right combination.
This isn’t Trujillo’s first time applying sound to coffee. He previously patented a similar system for cold brew, though those conditions were calibrated for cold brew’s milder, more diluted flavor profile rather than espresso’s concentration.
The taste test
Once the recipe was dialed in, 100 participants tasted both the ultrasonic and traditional versions without knowing which was which. They couldn’t reliably tell them apart. In some cases, the ultrasonic version actually rated slightly higher. “These findings showed that using ultrasound did not harm taste, and in some cases even improved it, despite brewing at room temperature and without the heat normally associated with coffee making,” Trujillo said.
Why this could matter beyond the home kitchen
A single espresso machine isn’t a major energy draw. But add up every café, every office, every hotel lobby running shots from morning through afternoon, and the numbers grow. The ultrasonic method uses about 25 percent of the energy a conventional machine requires. Trujillo’s goal is to see the technique adopted by large-volume coffee manufacturers, where the energy savings would add up to something no home kitchen ever could.
For now, the technology is still in the research phase. But it has cleared its biggest hurdle: the cup actually tastes good. In the coffee world, that’s not a small thing. People are particular.
Source study: Journal of Food Engineering—Ultrasound enables espresso-strength coffee brewing in 2-3 minutes at low temperature with lower energy consumption
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