Hear that? That’s the sound of an ultrasonic cold brew coffee ready in under three minutes

UNSW Sydney engineers have utilised sound waves to cut the time it takes to make a cold brew coffee from many hours down to mere minutes.

Fans of cold brew coffee often rave about the smoother, less acidic and less bitter taste compared to a regular hot brew.

There’s just one major problem – it takes anywhere from 12 to 24 hours to fully steep the grounds and allow the flavours to slowly be extracted using only cold water.

That’s far from ideal if you want or need your caffeine fix in a hurry in the morning.

However, engineers from UNSW have now developed a new way to make cold brew coffee in under three minutes – just like a regular hot brew – without sacrificing on the taste experience.

The process involves using an ultrasonic reactor to speed up the brew of the grounded coffee beans, with the research published in Ultrasonics Sonochemistry.

The ultrasonic brew

Addressing the challenge of speeding up the brewing process of a cold brew, the UNSW team led by Dr Francisco Trujillo, used an existing model of a Breville espresso machine and superimposed their own patented sound transmission system.

The system 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 within the reactor.