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Cold brew coffee—pew, pew, pew—brewed with lasers!

A new laser technology creates cold brew coffee in minutes. Even better: it tastes just as good and may be coming to a coffee shop near you.

Cold brew coffee—pew, pew, pew—brewed with lasers!
[Source Image: Tiago Lopes/Sketchfab/CC BY 4.0]

“Nobody wants to wait for 12 or 24 hours to get a cup of coffee,” says Anna Rosa Ziefuss, the German scientist who has achieved the impossible: making cold-brewed coffee in a record three minutes instead of half a day.

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Her secret ingredients? A laser. And endless episodes of The Big Bang Theory.

Ziefuss is a scientist in the technical chemistry department at the University of Duisburg-Essen in Germany. There, her colleagues use ultra-short pulsed lasers to synthesize and process colloids—microscopically insoluble particles suspended in a liquid. Colloids are generally used as thickening agents in anything from lubricants to beauty lotions. Usually, Ziefuss and her colleagues work with inorganic materials, such as gold or platinum. “Laser-based processing of organic materials like coffee is a rather new field of interest, at least in our group,” she says. But, when her doctorate supervisor, Stephan Barcikowski, encouraged her group to “think beyond their own research,” her brain went to caffeine.

“At the time, cold brew was very trendy in our working group,” she recalls. However, like anything that requires planning in advance, people simply forgot to brew it early enough in order to drink later. As odd as it sounds, given that Ziefuss worked with lasers all day, she discovered the solution to quick cold brew lurking in another interest: The Big Bang Theory TV series.

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“The actors irradiate everything possible with a laser,” she points out. And she had lasers, water, and coffee. The rest is this story.

On the left, there’s the optics used to enlarge the laser beam. On the right, the vessel that contains the coffee powder dispersed in water. The whole solution is stirred. The white spot shows the area where the laser meets the vessel. [Photo: courtesy Anna Rosa Ziefuss]

A clever method

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

Making cold brewed coffee is pretty simple. Basically, you make it by putting ground coffee in a cup with room temperature or cold water, leave it there for 12 to 24 hours, and then strain it to remove all the coffee particles. It’s just an infusion without the high temperature, which is what makes regular hot-brewed coffee happen so fast.

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Ziefuss’ idea was “to decrease the coffee powder size via pulsed lasers [to] increase the contact area of micro-powder with water.”

Increasing the area of contact of a substance to accelerate chemical reactions is not a new idea per sé. If you’ve ever had Hudson whiskey, you’ve actually tasted the product of this concept. As its founder and distiller, Ralph Erenzo, once told me, they accelerated the aging process of the whiskey by chance, using smaller barrels that increased the surface-to-liquid ratio, thus effectively increasing the area of contact for the liquid (a happy accident born of not having enough money to buy big barrels when they launched). Besides, micro-etching the interior of the barrels increases the contact surface even more, further speeding the chemical reaction that occurs when the alcohol interacts with the charred wood. The process with the coffee and lasers is wildly different than the whiskey and oak, but it has the same effect: increased contact surface that results in a faster chemical process.

Ziefuss and her colleagues used a stock, ultrashort pulse laser from the lab, arranging a series of optical lenses to enlarge the beam and point it at a vessel that contained the coffee powder. While regular cold brew sits undisturbed for several hours, in Ziefuss’ method, the solution gets stirred, and then the pulse laser fires at the vessel. Just three minutes later, they filter the solution through a commercial coffee paper filter to separate the excess coffee powder.

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

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

[Photo: courtesy Anna Rosa Ziefuß]

The future of coffee, tea, and much more

As exciting as instant cold brew coffee may be, Ziefuss claims that her laser method can be applied to all sorts of infused foods and drinks, and that she and her colleague Tina Friedenauer want to bank on it. They are in the process of creating a startup to further develop and commercialize their method. “We are still very at the beginning and believe it will require a larger portfolio of extracts before we enter the market,” she says. “Coffee was only the beginning, and we are currently investigating the laser-based extraction of tea and matcha.”

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The result could be a compact machine no larger than your average Nespresso. “The heart of such a machine is, for sure, the laser system,” she says. “We believe that a machine for extracting aroma components via pulsed laser can be in the size range of an automatic coffee machine.”

They don’t have a timeline for this magic box yet, but Ziefuss believes the device could scale well for cafeterias. And while a home-size model is not the first step in their business plan, this may change at a later time if there is a market for such a device. I would certainly love one in my kitchen. I really want to drink laser coffee.

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About the author

Jesus Diaz founded the new Sploid for Gawker Media after seven years working at Gizmodo, where he helmed the lost-in-a-bar iPhone 4 story. He's a creative director, screenwriter, and producer at The Magic Sauce and a contributing writer at Fast Company.

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