The wait is over – sound waves improve coffee experience

Cosmos Magazine


Cosmos is a quarterly science magazine. We aim to inspire curiosity in ‘The Science of Everything’ and make the world of science accessible to everyone.

By Cosmos

Coffee lovers rejoice – canny researchers have developed a way to bring you cold brew coffee in three minutes!

It normally takes 12 to 24 hours to fully steep grounds and allow the flavours to be extracted.

But a team from the University of NSW school of chemical engineering, led by Dr Francisco Trujillo has used an ultrasonic reactor to speed up the process, and published their research in Ultrasonics Sonochemistry.

The used a Breville espresso machine and superimposed their own patented sound transmission system, which connects a bolt-clamped transducer with the brewing basket via a metallic horn – transforming a
standard espresso filter basket into a powerful ultrasonic reactor.

The reactor works by injecting sound waves at a frequency of 38.8 kHz at multiple points through its walls
generating multiple regions for acoustic cavitation. This setup can double the extraction yield and caffeine concentration compared to unsonicated samples.

Coffee setup

“We are very excited about developing this technology that can be used by companies that already
manufacture coffee machines, so consumers can enjoy an ultrasonic cold brew…in less than three
“Very importantly, this breakthrough opens the door for coffee shops and restaurants to produce on-demand brews comparable to 24-hour cold brews, supplying the rising demand while eliminating the need for large semi-industrial brewing units and the associated requirement for extensive refrigeration space.”

Samples of coffee were sent to the Queensland Alliance for Agriculture and Food Innovation (QAAFI) at the University of Queensland (UQ) where they underwent a thorough sensory analysis.

Sensory Scientist and Flavour Chemist Professor Heather Smyth, a co-author of the paper, says the new method created a coffee as good as cold brew steeped overnight.
“Our trained sensory panel tastings proved that we can get a very similar taste profile to either a traditional cold brew or an espresso in the time it takes to brew a hot espresso.

How much coffee is enough?

The technology can be also used to speed up the brewing process of tea.

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