Few beverages have gained as much popularity in recent years as cold brew coffee. It is on its way to becoming a global billion-dollar market, largely because Millennials adore it. Others prefer it because they don’t have to fumble around with coffee machines in the morning.
However, if you do not purchase cold brew concentrate, the brewing time is at least 12 hours. And if, like me, you forget to steep the coffee in water the night before, you may have to forego your cold brew for the day. This may alter in the future.
In a study published in the journal Science of Food, German researchers from the University of Duisburg-Essen demonstrated a significantly faster method for preparing cold brew. And the procedure employs lasers.
What makes cold beer so refreshing?
The brewing method has a significant impact on the flavor of coffee. Cold brew is typically less acidic and less bitter than hot brew and even iced coffee (which is just hot brew cooled with ice). This occurs due to chemistry. The temperature of the water used to extract chemicals from coffee grounds is important. Cold water will extract a different chemical profile, and therefore a distinct flavor profile, than hot water. Therefore, hot brew and cold brew coffee are fundamentally distinct beverages.
For instance, the volatile aromatic compounds that fill your home with a distinctive nutty aroma whenever you brew hot coffee quickly evaporate at high temperatures. In contrast, cold-brewed coffee retains these aromatic compounds, which significantly alter its flavor.
Previously, a team of primarily Chinese researchers used ultrasound to reduce the time required for cold brewing from 12 hours to 1 hour. In this new study, however, German researchers upped the ante by demonstrating that the brewing time for cold brew coffee could be reduced to three minutes using lasers.
Lasers can, as one might expect, overheat materials. In order to prevent this, the authors employed pulsed lasers, which rapidly switch on and off — in this case, every picosecond (one-trillionth of a second). Three minutes of picosecond laser pulses were directed at a mixture of coffee powder and water. Laser irradiation warmed the beverage by approximately 5° C, but this does not disqualify it as “cold-brewed.”