UNSW researchers brew espresso with ultrasound and less energy

Researchers at UNSW Sydney say they have created an espresso-like coffee using room-temperature water and ultrasound, cutting energy use by up to 75%. Blind taste tests with about 100 coffee drinkers found the ultrasonically brewed version was indistinguishable from traditional espresso.

Why it matters: - The UNSW Sydney method could reduce the energy needed to make concentrated coffee drinks by about three-quarters. - The process could matter most for industrial coffee makers, where faster brewing and lower heating costs can scale into meaningful savings. - The same approach may also support ready-to-drink coffee products and concentrated bases for later dilution into other beverages.

What happened: - Researchers at UNSW Sydney developed a new coffee brewing process that uses ultrasound instead of hot water to make a drink with espresso-level intensity. - The work was led by Dr. Francisco Trujillo and the UNSW School of Chemical Engineering. - The research was published in the Journal of Food Engineering. - Blind taste tests found the room-temperature ultrasonic espresso was indistinguishable from traditionally made espresso.

The details: - The system uses a modified filter basket as an ultrasonic reactor. - A small metal transducer presses against the basket and generates high-frequency sound waves. - Those sound waves create acoustic cavitation, which forms and collapses microscopic bubbles in the liquid. - When the bubbles collapse near coffee particles, they help break up the grounds and speed extraction of flavor, aroma, oils and caffeine. - The process works with room-temperature water, so it avoids the energy cost of heating water. - The team says the brewing time is under three minutes. - The researchers say the method can reduce energy use by up to 75%. - The team tested extraction ratio, grind size and ultrasound exposure time to optimize the drink. - Finer grinding improved flavor extraction speed. - The best balance came at about two and a half to three minutes of ultrasound application. - About 100 regular coffee drinkers took part in the sensory test. - Participants evaluated aroma, flavor, bitterness and overall liking on a nine-point scale. - Four drinks were tested: traditional espresso, ultrasonic espresso, traditional filter coffee and ultrasonic filter coffee. - The drinks were prepared fresh, cooled to the same temperature, served in identical coded glasses and presented in random order. - The ultrasonic espresso matched traditional espresso on all taste measures, with no significant differences. - Participants were also unable to reliably tell the two espressos apart. - The ultrasonic filter coffee performed even better in the blind test and was preferred overall. - Participants rated the bitterness of the ultrasonic filter coffee as more pleasant. - Trujillo previously developed a patented ultrasonic system that made cold brew in about three minutes instead of the usual 12 to 24 hours. - The researchers note that cold brew tastes very different from espresso and contains about one-fifth as much caffeine.

Between the lines: - The key technical shift is not just faster brewing, but replacing heat with sound while preserving espresso-style concentration. - That matters because espresso has traditionally depended on hot water under pressure, so the UNSW method challenges a core assumption in coffee preparation. - The blind taste results give the technology credibility beyond engineering claims, since consumers could not reliably distinguish the ultrasonic espresso from the traditional version. - The stronger response from ultrasonic filter coffee suggests ultrasound may improve more than one brewing style, even though the espresso-like result is the headline use case.

What's next: - UNSW researchers say the system could be adapted into an automatic home coffee machine. - The bigger commercial opportunity is likely with large-scale beverage producers. - The technology could be used to make concentrated coffee for ready-to-drink products or shipped as a base for later dilution into drinks such as cold brew and milk-based coffee. - Trujillo said the team is confident the ultrasound system can be scaled to industrial needs with lower processing time and lower energy use.

The bottom line: - UNSW Sydney says ultrasound can produce espresso-strength coffee at room temperature, with consumer tests showing the result can taste essentially the same as a traditional shot while using far less energy.