Accelerating the extraction of Cold Brew with ultrasound

Cold Brew in Minutes? And yet, it happens!

Those who love Cold Brew, the coffee that is extracted directly into cold water, face a number of problems when they want to prepare it at home. After getting past the hurdles of proper grinding, correct water-to-coffee ratio, and effective filtering, the biggest and most intractable problem appears: time!

Cold extraction coffee is a time-consuming process, as the correct extraction of the coffee requires, due to the temperature of the water, times ranging from eight, twelve, up to twenty-four hours! Cold Brew lovers need to be proactive and constantly take care of their 'stocks', because if they run out of coffee, they'll have to wait... or not?

A new method can shorten cold extraction time to minutes, using ultrasound!

A revolutionary method for faster and tastier coffee

The method was developed by a research group at the University of South Wales. The researchers used an espresso machine, to which they adapted a sound system of their own development, which includes a metal speaker attached to the shutter basket of the machine, turning it into a powerful ultrasonic reactor.

The sonic reactor receives frequencies of 38.8 Hz at various points, which results in better extraction efficiency, higher caffeine concentration and faster extraction. Dr. Trujillo, a chemical engineer and member of the research team, explains: "Ultrasound speeds up the extraction process, as when the acoustic 'bubbles' pop into the ground coffee, they create micro-explosions capable of further breaking the ground coffee, making the extraction quite more intense and the aroma too."

However, since the extraction time of an espresso is already measured in seconds, what is not noticed is the dramatic reduction in extraction time. Dr. Trujillo adds that "the speed of extraction is unimaginable – we're reducing a process that normally takes 12 to 24 hours to less than three minutes."

As the method has a patent that can, under license, be used by coffee machine manufacturers, the day when we have Cold Brew at home in a few minutes from our machine may not be far away.



Reducing extraction time without collateral losses

As part of their research, the team sent samples of Cold Brew to specialized organizations for taste and aroma analysis, in order to be sure that their method does not negatively affect the final result.

The first sample had been "sonicated" at room temperature for one minute, the second for three minutes, and the third had been extracted by conventional cold extraction, without the experimental method. During the examination, the aroma, texture, taste and aftertaste of the three samples were studied. The results showed that an "ultrasonic" Cold Brew for a period between 2 and 3 minutes can produce a Cold Brew that will have practically no difference from the Cold Brew we know. In some cases, the result may be slightly more bitter, due to the higher concentration of caffeine, but this is something that can be easily adjusted.



If you are one of those who love Cold Brew, the time when you will drink it whenever you want it, without any preparation and without the need for patience, is closer than you think.