☕ The coffee of the future is made by replacing energy-hungry hot water with... sound waves!

The famous cup of strong espresso, a symbol of waking up for millions of people, could soon change its recipe. Australian researchers have succeeded in reproducing a perfectly authentic espresso using room-temperature water and sound waves. No more need to bring water to a boil under pressure: science paves the way for a more energy-efficient extraction.


Traditional espresso relies on a principle unchanged for over a century: water heated to 94 degrees Celsius (200°F) passing through finely ground and tamped coffee under a pressure of nine bars. While quick, this process is energy-intensive because machines constantly maintain large quantities of hot water, even during idle periods. The team from the University of New South Wales in Sydney wondered whether this heat was truly essential. Their answer, published in the Journal of Food Engineering, surprises with its audacity and efficiency.

Sound vibrations to extract aromas

The developed system replaces pressure and temperature with ultrasonic technology. A transducer, a small metal device, vibrates against the wall of the portafilter basket containing the ground coffee. These vibrations, inaudible to the human ear, propagate through water and coffee particles. They generate a phenomenon called acoustic cavitation: microbubbles form and collapse at lightning speed, creating micro-jets that act like brushes. These tiny forces crack the grain's surface and accelerate the release of aromatic compounds, oils, and caffeine.

The extraction is thus carried out in two to three minutes with room-temperature water, without any external heat source. The final drink reaches a concentration comparable to that of a classic espresso, with a dissolved solids content of around 10%. The researchers optimized several parameters, including grind fineness and water-coffee ratio, to achieve this result. Careful adjustment was necessary to balance flavors without diluting the brew.

Substantial energy savings

The most striking aspect of this innovation lies in its energy efficiency. In a comparative test conducted over twenty minutes, during which three espressos were prepared, the ultrasonic system consumed only about 24% of the energy used by a conventional machine. This 75% reduction is explained by the absence of a boiler and temperature maintenance. For household use, the savings may seem modest, but on an industrial scale, it takes on a whole different dimension.

Ready-to-drink beverage manufacturers, who produce millions of liters of coffee each year, could benefit from significant savings. The cold-extracted concentrate can be directly incorporated into recipes or transported more easily, paving the way for streamlined logistics. This avenue is particularly interesting for the rapidly growing markets of milk-based drinks and cold brew coffees.

Taste test validated by consumers

Technical performance alone is not enough: the result must please the palate. The researchers therefore organized a blind tasting involving about a hundred regular coffee drinkers. Participants evaluated four different beverages on a nine-point scale, rating aroma, flavor, bitterness, and overall appreciation. No significant difference was found between traditional espresso and its ultrasonic version for all criteria. Tasters could not distinguish them, and no marked preference emerged.

For filter coffee, the result even favored the ultrasonic method, judged more pleasant. Chemical analyses confirmed these impressions: caffeine and chlorogenic acid levels, a compound influencing bitterness, were equivalent between the two processes. Color and acidity also fell within the same statistical range, reinforcing the credibility of the approach.

Limitations to consider

However, this innovation remains confined to the laboratory. The prototype uses paper filters, which can alter the oil and suspended solids content compared to an espresso filtered through a metal mesh. Additionally, tastings were conducted at room temperature, which differs from usual tasting conditions where coffee is served hot. The researchers note that temperature strongly influences aroma perception.

The study also did not explore the effect of different roast profiles or bean origins on the process. Long-term reproducibility and adaptation to larger production volumes have yet to be demonstrated. Despite these reservations, this breakthrough opens a promising path to rethinking how we prepare our daily coffee, combining taste pleasure with energy efficiency.