UNSW researchers brew espresso intensity with ultrasound and less energy

UNSW Sydney researchers say they have created an espresso-like coffee using ultrasound and room-temperature water, cutting energy use by up to 75%. Blind taste tests found consumers could not reliably tell the ultrasonic espresso apart from a traditional one.

Why it matters: - The UNSW Sydney process could lower the energy and time required to make espresso-style coffee. - The biggest commercial upside appears to be industrial coffee production, where small efficiency gains can scale into major savings. - The method also could support ready-to-drink coffee products and concentrated bases for other beverages.

What happened: - Researchers led by Dr. Francisco Trujillo at UNSW Sydney developed an ultrasound-based brewing system that makes coffee with espresso-like strength using water at room temperature. - The work was published in the Journal of Food Engineering. - Blind taste tests with about 100 regular coffee drinkers found the ultrasonic espresso was indistinguishable from traditionally prepared espresso. - The team also tested ultrasonic filter coffee and traditional filter coffee in the same sensory evaluation.

The details: - The system turns a traditional filter basket into an ultrasonic reactor for coffee brewing. - A small metal transducer presses against the basket and generates high-frequency sound waves. - Those vibrations trigger acoustic cavitation, which creates and collapses microscopic bubbles in the liquid. - The collapsing bubbles help erode coffee grounds and speed extraction of flavor, aroma, oils and caffeine. - The process produced a concentrated coffee in less than three minutes. - Trujillo said the optimal brew time was between two and a half and three minutes. - The team said water temperature, grind size, brew ratio and ultrasonic exposure time were the key variables they tuned. - Finer grinding improved extraction speed. - The researchers said the process cut energy use by up to 75% because the water did not need to be heated. - The earlier Trujillo ultrasonic system had already been used to make cold brew in three minutes instead of the usual 12 to 24 hours. - The team said cold brew still tastes noticeably different from espresso and has about one-fifth the caffeine concentration. - In the sensory test, four drinks were compared: traditional espresso, ultrasonic espresso, traditional filter coffee and ultrasonic filter coffee. - All samples were brewed fresh, cooled to the same temperature, served in identical coded glasses and randomized to reduce bias. - Participants rated aroma, flavor, bitterness and overall liking on a nine-point scale. - The espresso versions showed no significant differences in taste measures. - The ultrasonic filter coffee scored better overall and was rated more pleasantly bitter than the traditional filter coffee.

Between the lines: - The results suggest ultrasound can preserve espresso character without the heat that normally defines the brewing method. - The stronger showing in filter coffee hints that ultrasound may improve some brew styles even when it is not aimed at duplicating espresso. - The claim that the system could scale for industrial users is the most important near-term business implication. - Trujillo is positioning the technology as both a coffee-engineering advance and a cultural one, tied to Colombia’s coffee identity.

What's next: - UNSW says the system could be adapted into an automatic home coffee machine. - The larger opportunity is likely in industrial beverage makers that want faster processing and lower power use. - The team says the concentrated output could be used directly in ready-to-drink coffee products or diluted into drinks such as cold brew and milk-based coffee beverages. - The researchers are continuing to refine the brew parameters for a commercially viable ultrasonic espresso.