The authors used a 38 kHz transducer with 100W of power. For $60 you can get a 2L ultrasonic cold brewer - it’s 40 kHz and 60W: https://m.vevor.com/ultrasonic-cleaner-c_11064/vevor-316-stainless-steel-2l-ultrasonic-cleaner-industry-digital-heated-w-timer-p_010173559579
Exactly.
Everything about this 'news' sounds sus.
But they are wearing lab coats.
Ultrasonic tech is so cheap & sold everywhere.
And like all agitation, it transfers heat (not like a microwave, as most heat is transferred to surrounding air, but heats up the liquid, and it mostly does so by heating/getting absorbed by the dense objects, ie grains, mostly surface).
Also, in case this somehow didn't exist for decades, all of it is just a bit better way of stirring - you can make cold brew by just mixing/shaking stuff. The coarser the grind the longer it would take to extract efficiently tho (but efficiency isn't rally the point, just taste?).
From the paper.
Ultrasounds accelerate extraction processes due to acoustic cavitation [8], [9]. When acoustic bubbles, also called inertial bubbles, collapse near solid materials, such as coffee grounds, they generate micro-jets with the force to fracture the cell walls of plant tissues, intensifying the extraction of the intracellular content [10].
Seems more involved than just aggressive stirring.
https://www.sciencedirect.com/science/article/pii/S1350417724001330
Cavitation is literally boiling, but the bubbles of steam are tiny, only last for an instant, and then collapse and cool back into the fluid.
That's not exactly what it's doing. Cavitation is when when the pressure of a liquid reduces below the vapour point. Heat isn't involved the liquid "boils" because the vapour point decreases with reduced pressure.
🤷♂️ Tomato / Potato. Cavitation occurs (the bubble formation) at a temperature below 100C, yes. As the steam bubble shrinks, very high temperatures are reached (super-heated steam). All of that energy, plus the latent heat of condensation is released back into the fluid. At that instant, there is a very small yet-to-be-mixed portion of liquid that may be near the boiling point. That small portion of fluid may undergo a warm-brew process as it cools and mixes. I'm kind of conceptualizing this brewing process like: what if you could heat, mix, and cool the coffee all at once everywhere. But I've never observed cavitation and bubble collapse with an ultra high-speed microscope camera, so my concept may be off a bit. I have seen photos of what it does to hardened steel hydropower turbines.
My next question would be, what if you start with ice water? That may give you something like true cold-brew. Another factor to consider is that I believe most cold brew is very oxidized. It might be interesting to try ultrasonic degassing for some period of time before the grounds are added, to see how much of the cold brew flavor is just oxidized coffee.
Yes, that is exactly how ultrasonic cleaners are used, it basically gets abrasive on the surface (like scrubbing with like a hammering motion, but on a tiny level).
The size of the bubbles is determined by the frequency (the higher it is the smaller the bubbles with lower energy each, the lower it is the bigger are bubbles and more powerful each).
So, if you are cleaning a large flat metal sheet, then you can go lower frequencies to speed up the process, whereas you would want higher frequencies for more intricate objects so the amplitude is smol enough to get into all the tight spaces for bubbles to form.
38kHz is a very common for ultra cheap household various purpose cleaner (jewellery, fruit & veggies, glasses, delicate clothes, etc), I have a 50kHz buttplug shaped one (so you put in a container and is not itself part of one).
Lab coats and pointing at a screen, give them the Nobel price already!
Not to mention the proper use of safety glasses whilst brewing coffee with 100W hi-tech.
I agree this is the kind of thing I should find on YouTube, not in an academic journal. But the paper does go into a lot of detail about extraction efficiency, so I guess there might be some useful measurements.
I am curious about the taste. It should be somewhere in between cold brew and hot, but probably closer to cold. Cavitation is a violent process. On a micro scale it’s literally boiling. Then the steam bubble collapses and is instantly cooled because of an almost infinitely big heat sink. So when cavitation occurs near the coffee grounds, some of the extraction would be at much warmer temperatures, for a brief instant.
Oh, yes, I was making fun of the headline, about inventing.
With that in mind basically any experiment/measurement/scientific theory is some sort of invention, it's just that we dont call it that.
Like, nobody invented the concept of tank, ppl "invented" materials, equipment, manufacturing & logistics/admin processes, etc that at one point allowed for a feasible "tank" to be compiled.
Yeah, they didn't even invent it. One company basically tried to do the same brewing technique commercially, but I guess they didn't get the word out in time: https://www.engadget.com/osma-pro-cold-brew-coffee-machine-review-131552500.html
You can buy sub 50 moneys liion battery operated lil machines ... that don't use 'sound pressure' but 'air pressure' to brew (lul).
That sounds so ultra
Definitely sound.
Really cool find!
Link to the article from Archive.org that doesn't require an account to read.
My Hero!
I would say not all heroes wear capes, but capes are dope and everyone should wear them.
If it can be done cheaply, or at least in the expected price ranges for coffee hardware, it could be good for people that make a business out of it. Or it could be good for big coffee shop to pump out more and charge more too with fancy marketing.
Honestly iced v60 is so much simpler.
What is that?
Pretty sure they're referring to Japanese style iced coffee. https://www.seriouseats.com/japanese-style-iced-coffee
Is going to be a patented process, so wait at least 20 years.to any commercially available home appliance to reach consumer markets.
Ain't no way vibrating beens is gonna be sued for. You may have to something different but the idea of vibrating bean can't be considered THAT novel, right?
Ianl but still
I hope this method also works with tea and yerba mate.
Honestly, this dude is pretty bad at making cold brew. Toddy takes 2 days. 12oz of coffee in a 2 quarts of water makes enough to have a coffee each day for a month, and it will last that long in the fridge.
That said - cool! More options at a coffee shop.
Hoping to mirror the great community of r/espresso.
We are a kind and accepting community for those who love, want to love, are getting into, or are interested in espresso and espresso accessories.
I didn't think we needed this section on Lemmy, but...
(No exceptions)
Here is the main resource from the same sub, since it's amazing.
If any of the original mods, or anyone else who loves espresso, would like to take control or help mod, please let me know. I'd be as happy to help as to pass the reigns.
A gracious community member has added some of the resources from the Reddit sub.
(I tried to grab all of the links from it, please let me know if I missed any)
<Wiki from r/espresso>
Links
Google Sheets List of Espresso Machines
Espresso Aficionados - Discord
Espresso Aficionados - Wiki (as of May 2023, this is the most up-to-date resource for machine recommendations and it has a bunch of detailed guides for how to dial in espresso, puck prep & troubleshooting, and more advanced techniques!)
Espresso 101 Espresso starts with the coffee bean. Fresher is better. As u/Beans_McGhee says, "The beans really need to be roasted within the month you use them for perfect espresso." Store-bought beans are fine, really—but part of the "fun" of espresso is trying different beans.
You grind your coffee beans using a grinder. This sub has lots of opinions on grinders.
The amount of ground coffee you use is called the dose. So when u/SingularLattice says, "Make sure you have the right dose for your basket", that's what he means.
A basket is the little metal cup that goes in your portafilter—that's the metal thing with a handle on it. Espresso machines often come with 4 baskets: a single and a double in both unpressurized and pressurized. Doubles are the larger ones; pressurized variants are a different shape and may say "dual wall" on the bottom.
You would use dual-wall if you are using pre-ground coffee. Almost everyone will make ("pull") double shots—when you get into weights and times, it's all based on a double. So you should likely use the unpressurized (single wall) double basket.
Advanced practitioners will dose by weight. Typically, you'd want ~7g for a single shot and ~18g for a double shot. Automatic grinders may dose by time: this will get you "close enough". Thus, the "single" dose will be around 7g and the "double" will be around 18g. (You can fine-tune these amounts—more on that later.)
Coffee grounds are light and fluffy, but you want them to be compact for espresso, so you tamp them (with your tamper). Advanced practitioners will calibrate their tamping pressure (e.g., with spring-loaded tampers)—don't worry about that. Just give it a reasonable amount of force. If you're putting your whole body weight on your tamper, that's too much.
You will get a feel for the right amount of force. You can also look at the level of the grounds in the basket. Use shape of your tamper or other tool to estimate how much space should be between your (tamped) grounds and the top of the basket.
As u/SingularLattice says, "You need to tamp FLAT, not hard. So long as it’s firm, you’re good."
At the advanced level, preparing espresso is all about ratios, namely weight and time. Generally, you want a 2:1 ratio in about 30 seconds. The 2:1 ratio means the ratio of your dose (i.e., ~18g) to the resulting espresso (i.e., ~36g). The process of brewing espresso is called extraction.
Many espresso machines will do this for you! When you press the double shot button, it will dispense enough water to make the "right" amount of espresso... presuming you're using the right basket and the right dose! With such machines (e.g., the Breville Barista Express, or BBE), what you should do is watch the pressure gauge. It should be in the "espresso range". (Advanced practitioners will measure pressure in bars—you want ~9 bars in an ideal world.)
If the pressure is low, you either need more grounds (higher dose)—which you can get by adjusting the grind amount—or a finer grind—which you can get by adjusting grind size. You may also need to tamp harder, but typically this isn't the problem.
(If your pressure is too high, the inverse is true... but this doesn't happen very often.)
Every bean is different, and so needs different settings to produce a good result—in your case, to keep that pressure dial where you want it. The process of adjusting these different settings is called dialing in.
Your goal here is a well-extracted shot. That's all about how it tastes! Espresso should be sweet and balanced. If it's sour, it's under-extracted (to which you would grind more and/or finer); if it's bitter or astringent, it's over-extracted (to which you would do the opposite).
Everyone here is adjusting all these variables (bean, pressure, grind size, dose, ratio, extraction time, and more) in search of the perfect shot!
(Derived from this post by u/basseq.)
What espresso machine should I buy? Great question, and a very common one. Generally, there are two key inputs:
How much do you want to “tinker” with your espresso? Do you want to play with different variables, or just wake up to a good coffee?
How much do you want to spend?
Espresso can be a very expensive hobby, so the answer to the second question can you get to the best bang for your buck.
Remember that espresso is not just the machine. The other notable expense is the grinder, which can be as much as—if not more expensive—than the machine itself. There’s also some key accessories (notably a scale) and the cost of good coffee itself ($15+/lb).
Recommendations by Budget <$500 – Bare Bones If you’re looking to step up from a Nespresso or just drink less Starbucks, start here. There are really two ways to go:
Manual ($250–$300) – Flair Neo ($125) + 1Zpresso JX ($130).
Automatic ($450–$500) – Breville Bambino ($350) + Baratza Encore ($170).
The DeLonghi Dedica ($350) is also a solid choice. For grinders, you can also check out the Breville Dose Control ($150), or upgrade to the 1Zpresso J-Max ($230). The Sette 30 ($300) and Mignon Notte ($320) grinders are solid, but may put you above $500.
If you’re really looking to do espresso on the cheap, forego the grinder and work with pressurized portafilters on the Neo or Bambino. Many of us started with things like the DeLonghi EC155 ($100), but it’s hard to recommend.
Keep in mind that the espresso you get in a cafe was ground on a grinder that cost around $2000 and brewed on a machine that cost at least $15,000. You can't shrink all of that into a sub $300 setup without a huge loss of quality. –u/MyCatsNameIsBernie
$500–900 – Entry Level If you think you’re “serious” about espresso, this may be a better entry point than above, which you might outgrow sooner than later. There are two common choices here:
All-In-One – Breville Barista Express ($750) or Pro ($850). While the community sees the built-in grinder as the weak spot (no upgrade path), and long-term reliability can be spotty, it an easy and popular entry point into the prosumer market.
Separate Setup ($800–900) – Gaggia Classic Pro ($500) + Baratza Sette 270 ($400) – The Gaggia is a classic and time-tested, with lots of options in the used market.
Something like a Bambino Plus ($500) or Lelit Anna ($570) might also work. There are a lot of good grinders in this range: the DF64 ($400), Eureka Mignon Silenzio ($470), Baratza Vario ($480), and Rancilio Rocky ($430) are all well-regarded.
If you’re strapped for cash, the r/espresso guidance is to prioritize the grinder. Better to run a cheaper machine (Bambino/Dedica) with a nicer grinder than the other way around.
$900–$1,500 – The Standard The endgame for many people, this range is probably the “sweet spot” for great espresso without going over the deep-end.
The r/espresso Standard – Rancilio Silvia ($850) + Niche Zero ($680) – The Silvia is a classic, moddable, and can be found used. For this price range, the alternate choice might be something like a Lelit Glenda ($900), or pairing a Gaggia with a nicer grinder. For grinders, ECM and Profitec both have offerings ($550), Baratza Vario W+ ($600), Eureka Mignon Specialita ($700), or any of the ones in the previous category. You can start mixing and matching machines and features and specs.
$1,500–3,000 – Prosumer We’re getting heavily into the “prosumer” market now, and there are less common machine+grinder pairings, so we’ll start looking at them separately.
Machines – Profitec Pro ($1,800), ECM Classika ($1,600), Lelit Elizabeth ($1,700), Rocket Appartamento ($1,700). The land of shiny chrome and lots of knobs. The Breville Dual Boiler ($1,600) is in this range too.
Grinders – Mazzer Mini ($800), Mahlkonig X54 ($750), Eureka Oro ($800).
$3,000+ – Dream Machines From here, it’s dream machine land and the art of the possible. If you’re asking, “What should I buy,” you probably shouldn’t start here.
Machines – Lelit Bianca ($2,900), ECM Synchronika ($3,200), Decent DE1 ($3,500), plus some offerings from Isomac, Rocket, Elektra, or Nuova Simonelli. You get into true “endgame” machines like La Marzocco Linea Mini ($5,900) or Slayer Single Group ($10,000).
Grinders – Eureka Atom 75 ($1,400), Mahlkonig E65S ($2,300), KafaTek Monolith Flat ($2,500), Weber EG-1 ($3,700).