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what do you Need to make good espresso? Ground coffee of course; machine Able to generate pressure. Hot water, preferably heated to a temperature between 195 and 205 degrees Fahrenheit. And that’s it. But can one do without this last ingredient? No, not the water itself, but the need to heat it.
Colombian researcher Francisco Trujillo led a team at Australia’s University of New South Wales that claims to have invented what it calls “ultrasonic espresso.” As Trujillo explains, it is “a room-temperature brewing process that uses high-frequency sound waves to extract flavour, oils, aroma and caffeine from ground coffee.”
Although the process takes longer than the traditional method (three minutes versus 30 seconds), it consumes 75% less energy, which is a huge benefit for cafes and restaurants, but especially for companies that produce industrial quantities of coffee, such as those that make ready-to-drink products.
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the Experimental system It directs the ultrasound waves directly to the filter containing the ground grains in the water. Instead of relying on heat, this technology exploits a phenomenon known as acoustic cavitation. This involves the formation and collapse of tiny bubbles that generate microcurrents which, in this experiment, facilitate their extraction Soluble compounds of coffee.
To generate these microcurrents, scientists designed a device capable of transmitting ultrasound vibrations through the entire filter basket, turning it into a kind of acoustic reactor. This design allows the waves to hit multiple points simultaneously and accelerate the movement of fluid around the coffee particles. “Ultrasound helps us replace heat with mechanical energy.” Trujillo explains.
The goal of this entire process is described in more detail in This month’s issue From the Journal of Food Engineering, it is to achieve a concentration similar to that of espresso. To do this, the researchers adjusted variables such as grind size, ultrasound power, and fermentation time. Using a fine grind and 100 watts of power, they obtained beverages with TDS levels and extraction yields equivalent to those considered ideal by the Specialty Coffee Association.
When the experiments were repeated under the same conditions but without ultrasound, these values could not be achieved. The ultrasonic system made it possible to produce coffee with a density similar to espresso in just minutes – the researchers found the optimal time to be between two and a half and three minutes – using room temperature water.
The team also analyzed various chemical agents. The concentrations of caffeine and chlorogenic acid were similar to those obtained by conventional methods. No significant differences in pH or in the overall composition of volatile compounds responsible for the odor were observed.
Taste test
A group of 100 people took part in sensory tests in which they compared ultrasonic espresso with traditional espresso. In the end, participants showed no significant preference for either method. Aroma, flavour, bitterness and overall acceptability scores were approximately equivalent.
They also compared filter coffee prepared using the traditional method and ultrasound. “In the case of filter coffee, the ultrasonically processed version was generally preferred, and participants rated its bitterness as more pleasant,” Trujillo noted.
In addition to replicating the sensory characteristics of espresso, the new technology could provide environmental benefits. Measurements by the researchers indicate that to produce drinks of the same density, the ultrasonic system used only 24 percent of the energy consumed by a typical espresso machine.
The authors stress that coffee produced using ultrasound is not identical to traditional espresso. However, the results indicate that it is possible to produce beverages with similar chemical and sensory properties without heating the water.
The research opens up the possibility of developing new coffee machines capable of preparing everything from espresso to filter coffee and cold drinks using the same technology. If these systems were introduced to the market, it would be possible to replace the distinctive sound of an espresso machine with the inaudible vibrations of ultrasound.
This story was originally published by WIRED in Spanish It was translated from Spanish.
