Scientists Use Ultrasound to Make Cold Brew Coffee in 3 Minutes Instead of 24 Hours

They have also invented something they are calling "cold espresso."
Scientists Use Ultrasound to Make Cold Brew Coffee in 3 Minutes Instead of 24 Hours
Image: UNSW
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A team of scientists in Australia say that they have found a way to make cold brew coffee in less than three minutes using an ultrasonic reactor. This is a potentially massive deal because cold brew normally takes between 12 and 24 hours to brew, a problem for me, personally, when I do not carefully manage my cold brew stock. The lead scientist on the research team tells me he has also created a “cold espresso,” which is his personal favorite and sounds very intriguing.

The researchers at the University of New South Wales Sydney claim that their ultrasonic extraction held up to a “sensory analysis” and blind taste tests by trained experts: “A sensory analysis was conducted to evaluate appearance, aroma, texture, flavor, and aftertaste, which demonstrated that coffee brewed for 1 and 3 min in the sonoreactor exhibited almost undistinguishable properties compared to a standard 24 hour [cold] brewing without ultrasound,” they write in a paper about the method in the journal Ultrasonics Sonochemistry

For the uninitiated, cold brewed coffee is made by soaking coffee grounds in cold or room temperature water in large batches to create a concentrate that you can keep in the fridge for a week or two. Because the water is not hot, the extraction from ground coffee beans takes much longer than it does with traditional hot brewing. The resulting cold brew is less acidic, less bitter, and sweeter. This long brew time isn’t a problem if you plan ahead, but, as mentioned, if you do not plan ahead, you cannot really speed up the cold brew time while continuing to have cold brew. As lead author Francisco Trujillo notes in the paper, the resulting large batches of cold brew concentrate also take up a lot of counter and fridge space, meaning that not every coffee shop or restaurant has it on hand. This is a phenomenon I am very familiar with, as many establishments currently on my shitlist claim that they have “cold brew” that is actually hot coffee poured over ice. 

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