Waterless Coffee-Making Methods

At its most elemental, brewing coffee as we know it requires quality beans and hot water, but researchers at UNSW Sydney developed a way to brew espresso-strength coffee—ultrasonic espresso—without heating any water. With this coffee-making method, hot water and high pressure are replaced with ultrasonic sound waves. Dr. Francisco Trujillo and his team at UNSW’s School of Chemical Engineering converted a traditional espresso machine filter basket into an ultrasonic reactor, triggering a process called triggered acoustic cavitation to form and collapse microscopic bubbles in mere minutes.

Research from a blind taste test, published in the Journal of Food Engineering, detailed that participants couldn't tell the difference between traditional espresso, ultrasonic espresso, traditional filter coffee, or ultrasonic filter coffee.