Laser brewed cold coffee?  Thanks Big Bang Theory!

Laser brewed cold coffee? Thanks Big Bang Theory!

“No one wants to wait 12 or 24 hours for a cup of coffee,” says Anna Rosa Ziefuss, the German scientist who has achieved the impossible: brewing cold coffee in a record time of three minutes instead of half a day.

Its secret ingredients? a laser AND endless episodes of Big Bang Theory.

Ziefuss is a scientist in the department of technical chemistry at the University of Duisburg-Essen in Germany. There, his colleagues use ultrashort-pulse lasers to synthesize and process colloids, microscopically insoluble particles suspended in a liquid. Colloids are typically used as thickening agents in anything from lubricants to beauty lotions. Ziefuss and his colleagues typically work with inorganic materials, such as gold or platinum. “Laser-based processing of organic materials like coffee is a fairly new field of interest, at least in our group,” he says. But when his Ph.D. supervisor, Stephan Barcikowski, encouraged his group to “think beyond their own research,” his brain turned to caffeine.

“At that time, cold brew was very much in vogue in our workgroup,” he recalls. However, like anything that requires planning in advance, people simply forgot to prepare it early enough to drink it later. Oddly enough, since Ziefuss worked with lasers all day, he discovered that the solution to rapid cold brewing lurked in another interest: Big Bang Theory T.V. series.

“The actors irradiate as much as possible with a laser,” he notes. And she had lasers, water and coffee. The rest is this story.

On the left is the optics used to amplify the laser beam. On the right, the container containing the coffee powder dispersed in water. The entire solution is stirred. The white dot shows the area where the laser meets the glass. [Photo: courtesy Anna Rosa Ziefuss]

A smart method

Cold brewing is considered by many to be a superior coffee extraction process, though it really depends on your taste buds. Ziefuss herself admits that at home she prefers to drink hot coffee made in a French press. But that’s as much about the flavor as it is about the preparation method; most of the time, she doesn’t have the patience or foresight to brew cold beer.

Making cold brew coffee is quite simple. Basically, it is prepared by putting ground coffee in a cup of cold or room temperature water, leaving it there for 12 to 24 hours, and then straining it to remove all the coffee particles. It’s just an infusion without the high temperature, which is what makes regular hot coffee happen so quickly.

Ziefuss’s idea was to “reduce the size of coffee powder through pulsed lasers [to] increase the contact area of ​​the micropowder with the water.”

Increasing the contact area of ​​a substance to speed up chemical reactions is not a new idea per se. If you’ve ever tasted Hudson whiskey, you’ve actually tasted the product of this concept. As founder and distiller Ralph Erenzo once told me, they sped up the whiskey aging process by chance, using smaller barrels that increased the surface-to-liquid ratio, thus effectively increasing the contact area of ​​the liquid (a happy accident born of not having enough money to buy large barrels when they were launched). In addition, the micro-engraving of the interior of the barrels further increases the contact surface, further accelerating the chemical reaction that occurs when the alcohol interacts with the charred wood. The process with coffee and lasers is very different from that with whiskey and oak, but it has the same effect: more contact surface resulting in a faster chemical process.

Ziefuss and his colleagues used an original ultrashort-pulse laser from the lab, arranging a series of optical lenses to enlarge the beam and aim it at a container containing the coffee powder. Whereas regular cold beer sits undisturbed for several hours, in the Ziefuss method, the solution is stirred and then the pulse laser fires into the container. Just three minutes later, they filter the solution through a commercial coffee filter paper to separate out excess coffee powder.

The result, as Ziefuss and colleagues describe in an article published in Nature, is a perfect cold brewed coffee with the same properties as the traditional one. Their chromatography and spectrometry data showed no statistically significant differences between the two methods. And the pH value, which “is associated with positive effects, such as the reduction of gastrointestinal symptoms” such as intestinal irritation (you know what I’m talking about), was also basically the same.

Beyond these technical tests, the laser coffee tasted just as smooth and delicate as cold brew, says Ziefuss.

[Photo: courtesy Anna Rosa Ziefuß]

The future of coffee, tea and much more

As exciting as cold instant coffee can be, Ziefuss says her laser method can be applied to all kinds of infused foods and beverages, and that she and her colleague Tina Friedenauer want to put their faith in it. They are in the process of creating a startup to further develop and market her method. “We are still very early days and we think it will require a larger portfolio of extracts before we enter the market,” she says. “Coffee was just the beginning, and we are currently investigating laser-based extraction of tea and matcha.”

The result could be a compact machine no bigger than your average Nespresso. “The heart of such a machine is undoubtedly the laser system,” she says. “We believe that a machine to extract aroma components using pulsed lasers can be in the size range of an automatic coffee machine.”

They don’t have a timeline for this magic box yet, but Ziefuss thinks the device could be well suited to coffee shops. And while a home-size model isn’t the first step in your business plan, that may change later if there’s a market for such a device. I would definitely love one in my kitchen. I really want to drink laser coffee.

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