A research team at the University of New South Wales, led by researcher Francisco Trujillo, developed an ultrasonic brewing process for coffee called "ultrasonic espresso." The process uses room-temperature sound waves to extract flavor and caffeine from ground coffee and consumes 75 percent less energy than conventional methods.

Trujillo, a Colombian researcher, described the process as "a room-temperature brewing process that uses high-frequency sound waves to extract the flavor, oils, aroma, and caffeine from ground coffee." The ultrasonic brewing process takes between two and a half and three minutes, while conventional espresso brewing typically takes approximately 30 seconds. The research, which was published in the Journal of Food Engineering, details the use of an experimental system that directs ultrasonic waves into a filter containing ground coffee beans and water. The technology uses acoustic cavitation, which involves the formation and collapse of tiny bubbles that generate microcurrents. The scientists designed a device to transmit ultrasonic vibrations throughout the entire filter basket.

The ultrasonic method produced beverages with levels of dissolved solids and extraction yields equivalent to those considered ideal by the Specialty Coffee Association. Experiments repeated without ultrasound did not achieve similar results for dissolved solids and extraction yields. Researchers used a fine grind and 100 watts of power for their experiments. Trujillo stated, "Ultrasound helps us replace heat with mechanical energy."

The concentrations of caffeine and chlorogenic acid in ultrasonic coffee were similar to those obtained by conventional methods. Differences in pH or the overall composition of volatile compounds responsible for aroma between ultrasonic and conventional coffee were not observed. Measurements indicated that the ultrasonic system used 24 percent of the energy consumed by a typical espresso machine to produce beverages of the same intensity.

A group of 100 people participated in sensory tests comparing ultrasonic espresso with conventional espresso. These participants showed no notable preference for either ultrasonic or conventional espresso, with scores for aroma, flavor, bitterness, and overall acceptance being virtually equivalent. Participants generally preferred the ultrasonically processed filtered coffee over the conventional version. Trujillo said, "In the case of filtered coffee, the ultrasonically processed version was generally preferred, and participants rated its bitterness as more pleasant."

No independent assessment of Francisco Trujillo’s claims was available.