Scientists Invent a Way to Brew Espresso With Ultrasonic Waves—No Hot Water Required

Colombian researcher Francisco Trujillo, leading a team at Australia’s University of New South Wales, has developed a novel method for brewing espresso that does not require heating water. Dubbed “ultrasonic espresso,” the technique uses high-frequency sound waves to extract flavor, oils, aroma, and caffeine from ground coffee while the water remains at room temperature.

Although the process takes about three minutes compared to the traditional 30 seconds, it consumes 75% less energy. This could be particularly beneficial for coffee shops, restaurants, and industrial coffee producers.

The experimental system directs ultrasonic waves directly into the filter containing the coffee grounds in water. Instead of heat, the method relies on acoustic cavitation—the formation and collapse of tiny bubbles that generate microcurrents, facilitating the extraction of soluble compounds from the coffee. The researchers designed a device that transmits ultrasonic vibrations through the entire filter basket, turning it into an acoustic reactor.

To achieve an espresso-like concentration, the team adjusted grind size, ultrasound power, and brewing time. Using a fine grind and 100 watts of power, they produced beverages with dissolved solids and extraction yields meeting the Specialty Coffee Association’s ideal standards. Control experiments without ultrasound failed to achieve these values. The optimal brewing time was found to be between two and a half and three minutes.

Chemical analysis showed that caffeine and chlorogenic acid levels, pH, and the composition of volatile aroma compounds were similar to those in conventional espresso. In sensory tests with 100 participants, no significant preference emerged for either method. For filtered coffee, the ultrasound version was generally preferred, with participants rating its bitterness as more pleasant.

Energy measurements indicated that the ultrasonic system used only 24% of the energy consumed by a typical espresso machine to produce beverages of the same intensity. The authors note that the ultrasonic coffee is not identical to traditional espresso, but it offers comparable chemical and sensory characteristics without heating water. The research paves the way for coffee machines capable of preparing espresso, filtered coffee, and cold brew using the same ultrasonic technology.