Australia engineers replace hot water with sound to make espresso

The University of New South Wales in Sydney, Australia, is revolutionizing the espresso-making process by demonstrating that hot water is no longer necessary. Engineers and food scientists have developed a technique called “ultrasonic espresso,” which leverages high-frequency sound waves to brew an espresso-style shot at room temperature in under three minutes.

In this innovative method, a small metal transducer attached to a standard espresso basket emits sound waves beyond the range of human hearing. This process induces acoustic cavitation, in which microscopic bubbles form and rapidly collapse, generating bursts of force that effectively break down coffee grounds.

This intense mechanical agitation efficiently extracts oils, flavor compounds, and caffeine from the coffee.

While the impact may not be immediately evident for home baristas, the implications for commercial beverage production are significant. The researchers estimate that eliminating the heating process could reduce energy consumption by up to 75%.

Additionally, brewing at room temperature enables immediate bottling and distribution without a lengthy cooling period.

Led by Dr. Francisco Trujillo, the UNSW team previously explored ultrasound for swift cold brews.

Yet, replicating the rich bitterness, aroma, and full-bodied nature of traditional high-heat espresso demanded meticulous adjustments in grind size, water ratios, and a specific exposure time of two-and-a-half to three minutes.

To validate their findings, the team conducted a blind taste test, published in the Journal of Food Engineering, in which 100 regular coffee drinkers sampled traditional hot espresso, ultrasonic espresso, and various filter coffee styles at the same temperature.

The results revealed that participants struggled to differentiate between traditional hot espresso and its ultrasonic counterpart, rating them similarly for aroma, flavor, and bitterness.

Notably, the ultrasonic filter coffee version received higher praise for its well-balanced flavor profile.

This breakthrough shows that the core qualities of espresso can be obtained without heat, potentially opening the door to a more sustainable future in commercial coffee production.