Cold-brewing of coffee by picosecond-pulsed laser extraction
nature.com
nature.com
It uses acoustic cavitation to extract flavor and caffeine from coffee without any heating in about one minute.
I use it every day and I like it. I love the strong flavor of cold brew, and my stomach appreciates the lack of acidity. There is a learning curve but if you're a HN reader, chances are the amount of experimentation required to dial in your version of perfection is an upside, not a downside.
I paid less at the time, but today the kit is selling for US$695. Note that as with all things coffee, it's only as good as your grinder. I ended up pairing my Osma with a Sette 270: https://baratza.com/grinder/sette-270wi/
but i'm with you on the grinder. i have the sette 30 and it's fast and consistent, with little waste. i primarily do single serving grinds for brewed coffee with it. the gearbox broke but baratza sent me a new gearbox for free (i believe there was a manufacturing defect in the early models). i got the 30 (the number of grind settings) because i wanted it primarily for pour over rather than espresso. the great thing is that the grind adjustment mechanism can be upgraded (along with the controller faceplate to get presets) and effectively turns the 30 into the 270, which i may do if i ever decide to get an espresso machine.
edit: i also got the courser burr, taking the grind size up to roughly a medium grind, which is perfect for pour over. the included burr is better suited to the fine grind needed for espresso.
Now I’ll gladly destroy any hipster cred I might have accrued saying the above: I do quite like stashing half a pot of yesterday’s coffee, in an open pint glass, to make iced coffee for the next afternoon.
What comes out of my Osma is fresh, ice chilled (by uh, ice), rich and all of the flavor notes are present. There's a nice foam on top that is technically not crema, but cavitation bubbles. It's strong like a well-poured Espresso shot, but with none of the burnt acidity.
I promise you that if you cupped what comes out of my machine alongside a literal glass of old, cold coffee... one tastes like victory and the other would make you gag.
it reminds me of the IPA fad with beer. i tried a bunch and they were generally extra bitter (and strong) rather than tasty. still don't get that one.
The majority of home and "prosumer" espresso machines use vibratory pumps - how is this any different? Also, the recirculation of already brewed coffee back into the pump seems really strange to me. Didn't the coffee world decide percolators we're gross a couple decades ago precisely because of this reason?
This looks like an interesting machine, I wonder if there's a way to try one?
I'm not sure what a vibratory pump is, but acoustic cavitation is the same kind of action you can use to clean silver or wash clothes. Millions of tiny bubbles. Try a Google search for "acoustic cavitation cleaner".
When the Mentos + Diet Coke thing was first a big thing, a friend of mine who ran a biotech firm (so was always writing funding proposals), submitted a proposal for an aerosolizer using a similar process, as a mass dispersal system for the military, if I recall correctly. Don’t know if it ever got funded, though.
https://youtu.be/BHiWygziyso?t=943
Devil's Toothpaste
Stick ground coffee in some filter bags and put it in some cold water in the fridge. Come back the next day and drink it. Leave it in there however long you want.
Use the fridge - trust my experience. It may take a bit longer to brew at colder temperatures, due to decreased convection of the liquid, but it will taste much better, as it prevents bacterial and fungal growth.
More here - https://kitchenappliancehq.com/can-cold-brew-coffee-mold/
Not saying that mold is impossible, but I don't think the solutions is to buy their amazon affiliate coffee maker and special coffee butter.
If you have mold issues after 24 hours of cold brewing I think you have some deeper issues at play. Consider getting mold tests for your house, sterilizing the tools/containers you use, and switching out your beans.
I generally face it 3-4 days in, not 24 hours.
Wet coffee grounds will grow mold quicker than any other food product I've seen.
Even a pot of coffee will get mold on the top within like a week.
That water turns out fine, often for weeks at a time.
Store the cold brew out of direct sunlight, don't leave the grounds in for a super long time, and you'll be fine. It's not like brewing alcohol, you're not adding a bunch of sugar to it or anything like that. The coffee grounds you're adding are shelf-stable, the water you're adding it to is shelf-stable, you're not introducing any real food for bacteria/fungus. Water will eventually go off if you leave it in direct sunlight (mostly due to algae), especially after introducing extra organic matter, but the actual risks of following established methods for brewing cold-brew at room temperature are very low in my opinion. Especially chlorinated water like you probably get out of your pipes.
>> "Furthermore, the liquid phase’s alkaloid content, analyzed by reversed-phase liquid chromatography coupled to high-resolution mass spectrometry, is dominated by caffeine and trigonelline and is comparable to traditional cold-brewed coffee rather than hot-brewed coffee. Furthermore, analyzing the head-space of the prepared coffee variants, using in-tube extraction dynamic head-space followed by gas chromatography coupled to mass spectrometry, gives evidence that the lack of heating leads to the preservation of more (semi-)volatile substances like pyridine, which provide cold-brew coffee its unique taste. "
This is why temperature / pressure / flow rate are so important to good espresso - some of the heavier compounds taste very bitter and including much of them in the brew makes for an unpleasant drink.
Later on the trip I bought a Turkish coffee maker, which works on the same principle, so it's not so much an innovation as it is a hotel survival tip.
Glad you prevailed! My nightmare scenario is having coffee, but no way to grind it.
And the cupping procedure doesn't even do that, but still produces reliable tasty cups.
It’s obviously weaker than hot coffee, but though I drink my hot coffee black, I prefer a weaker iced coffee with a bit of milk or cream. The only way to get a really strong iced coffee is either to brew hot and let it cool before pouring over ice or to make coffee ice cubes, both of which are too much trouble for me.
So between pouring stronger hot coffee over ice which melts a lot of the ice or pouring weaker cold brew over ice and melting less ice, the dilution ends up about the same, but the flavor profile is different with the cold brew being more subtle and less acidic. Truthfully I enjoy it both ways. Just depends on my mood.
The Aeropress is very flexible. Experiment with it. No one brew will work for all beans/roasts. I’ve found some beans/roasts taste better brewed at 175° and others at 190°. Besides the Aeropress, the thing that upped my coffee game the most is an electric kettle.
Other than percolated, there’s almost no brewing method I don’t enjoy. I use an Aeropress most of the time, but I also make coffee in an ibrik, a mokapot, a Chemex, a simple silicone pour over mold; it just depends on my mood.
The only style of coffee I gave up on at home is espresso. I was just never able to pull consistent shots and got tired of how much work it was to clean the machine and the space it took on my counter. And before you say it: I just can’t countenance pod machines.
(Just saw you use room temp water; I use hot and let it brew for like 2min. Do you get a strong enough extraction? How long do you let it go for?)
The gist of it is: 1. Grind finer (like, nearly espresso fine) 2. Steep for much much longer (like 10 minutes) 3. Don’t press too hard
(3) is generally applicable advice and may already improve your current results. Pressing too hard results in channeling and uneven extraction.
Of course, goes without saying, use good coffee and an appropriate grinder.
Do you use a metal mesh or paper filter?
Do you get enough pressure from your Aeropress? I've had several over the years and sometimes the plunger heads (the rubbery part going towards coffee) could be too loose as they can become weak over time.
Or your coffee is ground too coarse perhaps?
The point is you need proper pressure and a slow push. The plunger and ground size impact the pressure most IMO.
Of course, without the filter you won't get pressure at all :) And if you use the inverted method and forget the filter (like me, several times), once you flip over the Aeropress, your kitchen ends up smelling awesome.
The water temperature should not be boiling or you'll burn the coffee, possibly making it taste bad. I tend to use 94-95 degrees Celsius unless advised otherwise.
An Aeropress won't create a flavor smash like espresso, there's not enough pressure for that. But for my admittedly crude and uncultured taste buds it can basically beat a coffee machine.
For espresso-like strong coffee, I just use the good old Moka pot. Slightly more work than Aeropress, especially regarding the cleanup, but not that much.
Also, a tip about the ice cubes: make strong coffee with the Moka pot, freeze, then dump the cubes into a smoothie blender (with milk if you like) before drinking. Saves you the mindfulness exercise of watching ice cubes melt.
Sure, you can just make some that will be ready tomorrow. But if you want some right now, it seems legitimate that being able to press a button and get cold brew is novel.
If that doesn't sound like you, don't buy it.
Cafes will make an effort to increase extraction yields 1% because that means 1% less coffee needed over the many pounds used per day.
I happen to like coffee with fruit and citrus tones. I'm not a coffee bore, but I have understood that coffee bores refer to that fruitiness as "acidity". Does that mean that cold-brew would be less fruity? The authors take "acidity" to mean "pH", which is obviously easier to measure than "fruitiness", but I wouldn't describe the taste of e.g. spirit vinegar as "fruity".
Supplementary question: why's it got to be a picosecond laser? They say that a nanosecond laser's pulses are too long, and cause heating. How hot does it have to get for that to be a problem? Can't you just cool the brewing vessel?
Supplementary supplementary: can apparatus for doing this be built at home? How much ps-laser power needs to be delivered to the brew? At what wavelength? You can get handheld picosecond lasers for things like mole and tattoo removal, for under $100; would one of those do the trick?
I also like lighter-roasted fruity beans, and cold-brewed tends to reduce the "sourness". IMO cold brew really shines for non-fruity beans though, greatly reducing the bitterness.
You should try it!
I find that cold brew tastes the same no matter the quality of coffee (therefore great for lower quality coffees) where as Japanese iced coffee retains the original notes of the coffee.
PS: ofc I could google that. But then again google results these days are…
You can also use a regular drip machine though. Use half the normal water. Add the equivalent ice (by weight) to the flask. Brew as normal, but turn it off as soon as it's finished. The slow drip of hot coffee is cooled immediately as it hits the ice.
Since the brewed coffee is cold, you can add extra ice to your cup without it melting and diluting the taste too much.
Adjust the water / ice ratio as desired.
That powerful beam looks like (dangerous) fun; I've always wanted a laser that can burn things. My inner arsonist would like to be able to set things on fire from 100m. But I'm sure the device must be illegal here.
Styropyro says you can damage your eyes just by looking at the projected laser spot. I wonder whether he's exaggerating his warning a bit.
OK, so no homemade picosecond-laser coffee for me any time soon.
That would likely be seeds of Coffea arabica - one of three coffee plants. Those tones come from a specific plant rather than a brewing method or temperature.
The other popular is C. canephora (robusta coffee) which is almost globally (outside espresso world) considered as inferior to arabica and cheaper. Robusta has some chocolate and nut aromas but some people would say that it resembles burned rubber stench.
The third plant - C. liberica - is very rare in comparison. To me it has a somewhat woody/smoky/fruity aftertaste but I have only tasted beans from two roasters so far.
Most of store-bought ground coffee are arabica/robusta blends so people can enjoy full taste spectrum but aren't discouraged by the burned rubber thing.
I, on the other hand, LOVE robusta and my morning ritual of throwing mainly robusta roast (currently from Harley Estate in India) with 5-25% arabica seeds of choice into coffee blender is the best and most benefiting first decision making process I can imagine in the early morning.
> Those tones come from a specific plant
No doubt; but I'm sure that "terroir" and growing conditions are also important.
Also, from what I can tell there are two ways of separating the berry-pulp from the bean: mechanical separation and wet fermentation, which create different flavour profiles.
The two I'm alternating at the moment are both pure arabica, both from East Africa, and both high-grown; but they seem to be processed differently.
The current US Barista Champion (Morgan Eckroth) did use C. eugenioides in one of her beverages, but that is still priced out of reach for all but the most dedicated enthusiasts.
Robusta is only used in "traditional" espresso blends (meaning the original Italian style) or, stereotypically lower quality products. (Edit: not to denigrate anyone's choice of using Robusta in their morning cup - please do whatever you enjoy the most.)
The thing about arabica is that there are many different varieties, from Ethiopian heirlooms to Typica, Bourbon, Pacamara, Gesha, etc. They are grown in varied soils, elevations, and climates. And as a sibling comment points out, the "natural process" and experimental fermentations are becoming popular because of the secondary flavors imparted. (Though my view of the scene is that most snobs still scorn natural process coffees for lacking cleanliness).
The brewing method and temperature will ABSOLUTELY alter the flavor tones of the cup. And the quality of grinder is the most important factor by far. Tweaking grind size can take you from a flat, mediocre cup to something with distinctive flavors and sweetness.
There's absolutely nothing about cold brew coffee that is anything like unsweetened lemonade. I'm cringing just reading this.
What it does taste like is super-strong coffee, with none of the burnt note that comes with heated coffee. It could very easily be considered "too strong" by supertasters... but unsweetened lemonade sounds like dishwater.
Light roasted (aka "Nordic" or "third wave") beans will produce more acidic cups because of their different chemical components. They are also less likely to taste burnt or astringent.
For those in the bay area, Red Rock in Mountain View has this issue with their brewed coffee. It's often downright sour.
Watching YouTube videos on smoking / flavouring liquor using these cleaners gave me the idea.
And that jar goes in the cleaner
https://www.scinexx.de/news/technik/skurril-cold-brew-per-la...
(Extracted via acoustic cavitation.)
To the extent there's a surprising secret, the coffee will taste better if you grind it fine like espresso rather than coarse like you normally would for French press/drip coffee.
Where can I find cheap lasers to try something like this?
You might be able to find a laser system to hack around with (they are used for tattoo removal). Probably not cheap.
Make sure to take laser safety super seriously if you work with lasers https://ors.od.nih.gov/sr/dohs/safety/laboratory/Pages/laser...
In fairness, did anyone notice a finding in this paper that might lead to a cost-effective process by a different technology?
Was this the April 1 issue?
Is this good, important, or foundational science? I do not think so, but there may actually be practical applications for rapid production of high-caffeine cold brew coffee.
Do you find the method fraudulent or were the outcomes poorly selected or measured?
IMO statements like this have no place in scientific papers. Attributed by whom? Less bitter than which method of hot brewing? Fewer acids than what - coffee made with all hot brew methods including AeroPress?