Preparing cold coffee has always been a process that requires patience: the traditional method to obtain a «cold brew» It can take between 12 and 24 hours, as the coffee properties are slowly extracted using only cold water. Now, a team of engineers from the University of New South Wales has managed to drastically reduce this time to less than three minutes through the use of ultrasound.
Ultrasound technology: How it works
The process developed by Dr. Francisco Trujillo and his team involves the use of an ultrasonic reactor that is integrated with an espresso machine. This reactor generates 38.8 kHz sound waves that are transmitted through a transducer and a metal horn connected to the filter of the coffee maker. The sound waves create multiple regions of acoustic cavitation that, when interacting with the ground beans, accelerate the extraction of oils, aromas and flavors.
Faster and more efficient extraction
Dr. Trujillo explains that this acoustic cavitation process reduces the extraction time from 24 hours to less than three minutes, by generating microjets capable of breaking the beans and releasing the aromatic and flavor properties quickly. Furthermore, the study published in Ultrasonics Sonochemistry revealed that the reactor can double the extraction yield and concentration of caffeine compared to samples that do not use ultrasound.
Sensory evaluation
In collaboration with researchers from the University of Queensland, sensory evaluations were carried out on samples prepared using this process. The tests compared samples sonified for one and three minutes with a traditional 24-hour infusion at 4°C. The result was surprising: the coffee sonified for one minute presented a profile similar to that of 24 hours, although with a slightly lower aromatic intensity. On the other hand, the three-minute one achieved an aromatic intensity comparable to the 24-hour one, but with a slightly higher bitterness.
Impact on the beverage industry
The application of ultrasound in the production of cold brew not only allows for a faster and more efficient method, but can also be implemented in the production of other beverages such as teas. This innovation provides the possibility of reducing the need for mass storage and cooling units, something crucial for an industry that is increasingly seeking sustainability and efficiency.
Dr. Trujillo is optimistic about the potential impact of this technology: “We are excited about the development of this technology that can be used by coffee maker manufacturers to offer consumers an ultrasonic cold brew in less than three minutes. Additionally, it opens the door for cafes and restaurants to meet growing demand without large refrigeration units.”.
The application of this method could transform the way cold brew coffee is produced, providing a fast and sustainable alternative for cold brew lovers, while reducing the environmental footprint by reducing the use of resources for its storage.
Via www.unsw.edu.au
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