As the temperature rises, many people are switching from hot coffee to iced coffee. people who drink coffee especially those with sensitive stomachs, prefer iced coffee due to its lower acidity, which makes it their preferred year-round caffeine source. This smoother, creamier, and sweeter brew is made by letting coffee grounds soak in cold water for over 24 hours. Unlike hot brewing, the longer time and cooler temperatures reduce the acidic content and allow the coffee's remaining compounds to mix together. cold brewThe demand for iced or cold brew is increasing at coffee shops. However, making these chilled drinks can be a problem, as producing the properly flavorful, less bitter concentrate shots usually takes 24 hours of refrigeration.
The rise in demand for iced or cold brew drinks is causing logistical challenges at coffee shops. the process of cold brewing requires 24 hours of refrigeration to create a properly flavored, less bitter concentrate.
A group of researchers at the University of New South Wales in Australia decided to try a more intense brewing method to reduce waiting time. They used ultrasonic waves to blast coffee grounds. ground coffee beans with using sound waves with a very high frequency. According to chemical engineering professor Francisco Trujillo, this is now his preferred way to drink coffee. Trujillo revealed this during a recent conversation with the publication New Scientistand discussed his team's work in the journal Ultrasonics Sonochemistry.
The researchers stumbled upon this time-saving method while working on a different soundwave experiment. They wanted to see if breaking up coffee grounds using acoustic cavitation could increase the levels of antioxidants. They connected a Langevin transducer to a Breville Dual Boiler BES920 espresso machine and used 38.8 kHz frequency sound waves to blast the coffee. Although the antioxidant levels stayed mostly the same, the resulting coffee was remarkably delicious.
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Through further experimentation, the researchers improved their cold brew shots. In one setup, they exposed the espresso to 60 seconds of ultrasound waves while pumping water at room temperature through the grounds at 12-second intervals. In another setup, they extended the total time to 3 minutes. Both methods were then subjected to taste tests at the Queensland Alliance for Agriculture and Food Innovation to evaluate the texture, flavor, smell, and aftertaste of the coffee.
The results? The 1-minute brew received similar scores to the traditional 24-hour method, although it seemed less aromatic—suggesting that it was under-extracted. The 3-minute brew restored the aroma intensity, but it also made the brew slightly more bitter. Essentially, it seems that a duration between 1-3 minutes of ultrasonic acoustic cavitation can produce a cold brew of comparable quality to the traditional method, without the long wait.
Of course, the time saved by scientists was initially offset by costs. According to New Scientist, the first setup with the espresso machine and transducer cost nearly $10,000. However, Trujillo noted that further improvements reduced the expenses to "a fraction of the cost." Nevertheless, even if the ultrasonic method never leaves the lab, at least Trujillo's team will have enough caffeine to continue working on future coffee technology advancements.
