Coffee, the nectar of the gods, the black fuel that keeps modern society running, is about to receive an upgrade. Specifically, cold brew coffee.
The world of coffee is immensely broad and diverse. From the simple espresso to the foamy cappuccino and the hardcore doppio, there are a million variations to coffee, each with their own particular flavor.
Cold brew coffee is often said to be different from hot coffee — we’re not talking about hot coffee with ice, we’re talking about coffee that was brewed without heat. Steeping coffee beans in cold water extracts up to three times more caffeine than drip-filtering with hot water. This makes a less bitter and less acidic coffee with a different chemical profile that could even be healthier than regular coffee. But cold-brewed coffee isn’t exactly convenient to make.
A cold brew takes about 24 hours to steep and, already, it’s easy to see how this can be a problem. Even with modern equipment, the process can only normally be accelerated to 12 hours. If you’re organized enough to do this at night for yourself, that can work, but for people who find this type of planning impractical, or for coffee shops who can’t be sure how much they’ll sell, this just doesn’t work.
This is where lasers enter the scene.
When you think of lasers, you’re probably thinking of something hot. But lasers have been used to cool atoms for over four decades now and they can also be used to trigger and exacerbate chemical reactions — as was the case here. In the work, a research team from the Universitat Duisberg Essen (UDE) in Germany demonstrated a process that can cold brew coffee in just a few minutes, delivering the same flavor and much of the chemistry of traditional cold-brew coffee.
The approach is derived from a field called laser synthesis and processing of colloids (LSPC). Essentially, the researchers took a specially processed garnet crystal and used it to create a laser pulse that lasts just 10 picoseconds (0.000,000,000,001 seconds). The laser was pulsed through a solution of ground coffee and water at a rate of some 80,000 pulses per second. The process only raised the temperature of the coffee by a few degrees but it greatly accelerated the steeping of the coffee in the cold water.
In terms of acidity, laser coffee was similar to traditional cold-brewed coffee. There were also no additional substances that weren’t already present in either hot or traditional cold coffee. Aromatic compounds (most notably, trigonelline) were found to be somewhere in between the hot brew and the traditional cold brew for the laser coffee.
The main downside of the project, at least with the current approach, is that the level of caffeine in the laser coffee was not higher than that of the hot coffee, but researchers say that if the method was used a few more minutes, the caffeine level would have been likely to increase as well.
“In summary,” reads the study published in the journal Nature, “we recorded a similar [chemical] profile for all coffee variants. The cold brew and the ps-laser-brew show the highest alkaloids’ concentration, while their amount in the hot variants is decreased … The chemical composition of ps-laser-extracted coffee is very similar to conventional cold-brew coffee.”