A team led by Colombian researcher Francisco Trujillo at the University of New South Wales says it has developed “ultrasonic espresso,” a room-temperature brewing process that uses high-frequency sound waves to extract espresso-like flavor—without heating wate
A coffee order usually arrives with the sound of heat—the steady hiss of a machine and the promise that hot water will do the work. This new experiment tries to break that habit.
Led by Colombian researcher Francisco Trujillo. a team at Australia’s University of New South Wales is developing what it calls “ultrasonic espresso”: a room-temperature brewing process that uses high-frequency sound waves to extract the flavor. oils. aroma. and caffeine from ground coffee. Trujillo describes it as replacing heat with sound-driven force, saying, “Ultrasound helps us replace heat with mechanical energy.”.
In conventional espresso. time is fast and heat is central: typically three minutes versus about 30 seconds for the usual method. according to the researchers’ comparison. But the longer brewing period comes with a trade-off shops may actually want—energy savings. The team claims the process consumes 75 percent less energy. a benefit that could matter most for businesses producing industrial quantities of coffee. including companies making ready-to-drink products.
The experimental setup is built around an unusual idea: instead of heating water and passing it through grounds. ultrasonic waves are directed into the filter containing the ground beans in water. The mechanism the scientists rely on is acoustic cavitation—the formation and collapse of tiny bubbles that generate microcurrents. In this experiment, those microcurrents help facilitate the extraction of soluble compounds from the coffee.
To make those waves effective across the basket. the researchers designed a device that transmits ultrasonic vibrations throughout the entire filter basket. turning it into what they describe as an acoustic reactor. The waves can then hit multiple points at the same time, accelerating the movement of liquids around coffee particles.
The goal is not just “coffee-like” results. The researchers say they aimed for a concentration comparable to that of an espresso. reported in this month’s issue of the Journal of Food Engineering. They adjusted variables including grind size, ultrasound power, and brewing time. With a fine grind and 100 watts of power. they produced beverages with levels of dissolved solids and extraction yields equivalent to those considered ideal by the Specialty Coffee Association.
When the experiments were repeated under the same conditions but without ultrasound, those targets were not achievable.
They also narrowed down the timing: coffee brewed with ultrasound could reach espresso-like intensity in just a few minutes. with the optimal window found between two and a half and three minutes—using water at room temperature. The team further measured chemical parameters. They report that caffeine and chlorogenic acid concentrations were similar to those obtained by conventional methods. and that there were no significant differences observed in pH or in the overall composition of the volatile compounds responsible for aroma.
Whether people actually notice the difference is where the story becomes more grounded. A group of 100 people took part in sensory tests comparing ultrasonic espresso with conventional espresso. The participants showed no notable preference for either method. Scores for aroma, flavor, bitterness, and overall acceptance were virtually equivalent.
They also compared filtered coffee prepared conventionally with filtered coffee prepared using ultrasound. For that comparison, the ultrasonically processed version was generally preferred, and participants rated its bitterness as more pleasant.
The potential impact doesn’t stop at taste. The researchers say their measurements indicate that, to produce beverages of the same intensity, the ultrasonic system used just 24 percent of the energy consumed by a typical espresso machine.
The authors stress that coffee produced using ultrasound is not identical to traditional espresso. Still, the results suggest it may be possible to make beverages with comparable chemical and sensory characteristics without heating the water.
Looking ahead. the work points to coffee makers that could use the same ultrasonic technology across formats—espresso. filtered coffee. and cold brew. If such systems ever reach the market. the familiar clatter and heat-driven sound of an espresso machine could give way to vibrations you can’t even hear.
ultrasonic espresso Francisco Trujillo University of New South Wales Journal of Food Engineering acoustic cavitation coffee brewing technology Specialty Coffee Association energy savings cold brew filtered coffee