Making espresso with ultrasound
unsw.edu.au57 points by darktoto 9 hours ago
57 points by darktoto 9 hours ago
This is really cool, I have so many questions! What's interesting to me is they only replaced the hot water part of the equation, and the system still requires high pressure.
How does ultrasound affect flow rate? Do fines sink to the bottom of the puck and choke the shot?
There is a new movement happening, especially in lighter roast coffees, where we're finding that more balanced extractions (less bitterness/acidity/acridity) are happening at lower pressures, even going so far as grinding so coarse that the puck offers zero resistance - effectively making the pump the limiting factor for flow rate. Light roast coffee is much less porous and more hydrophobic.
I wonder if adding ultrasound would allow light roasts to yield more extraction in general, maybe even keeping the high temperature. Or, would adding ultrasound allow a finer grind size and more resistance without adding the harsh flavors of a high-temperature shot.
So many experiments to be done!
This sounds awful. I’m an espresso snob and caffeine isn’t even on my list of why I love it. It’s like they complete ignored what makes a good shot and focused on one element.
I'm curious why you focused on caffeine when the article says their study found that people tasted no difference
> “And when we gave our ultrasonic espresso to 100 regular coffee drinkers in a randomised test, they could not tell it apart from a normal espresso.”
I like the ritual of it, for sure, but I'm not sure that's what makes it a good shot?
Regular coffee drinkers vs snobs are two vastly different categories. In the guy that ruins your fun. ;)
I grow my own beans and harvest rain water from my roof to use in my coffee ritual and ... am happy to let others do their own thing
> Both espresso samples were served at 22 °C to ensure a fair like-for-like comparison […]
> It is noted that espresso is normally consumed hot and has transient sensory attributes that are temperature- and time-dependent. Hence, serving espresso at 22 °C will alter its sensory characteristics.
This is a weird test, coffee get’s so much worse when cold. So people can’t distinguish between two bad coffees.
> coffee get’s so much worse when cold
This is a myth. Bad coffee tastes better when hot because your sense of taste is dulled - reducing bitterness. Also, at higher temperatures, aromatics and volatile compounds are more airborne, improving the smell of coffee. Good coffee is better enjoyed around 60-70C
> coffee get’s so much worse when cold
Coldbrew is a thing and done right it brings out a refreshing sweetness. Also iced coffee. Bad coffee is bad hot or cold.
"Good" (well-extracted) coffee is still relatively good when warm, especially compared to "bad" (over-extracted, or under-extracted) coffee. That said, many believe that the optimal temperature for serving coffee is 50-60 degrees celsius (122-140 degrees fahrenheit).
Does this work with cold water? Because if so, my iced espresso drinks are crying out for it
Where's James Hoffmann when you need him?
What exactly is the innovation here compared to the press release from two years ago?[1]
[1]: https://www.unsw.edu.au/newsroom/news/2024/05/Ultrasonic_col...
Different kind of coffee drink being prepared; espresso vs cold brew.
(You might quibble whether it's actually espresso if there's not pressure and it's extracted cold; but it's closer to espresso in strength.)
Of all the objective and subjective metrics a home coffee drinker is trying to optimize, never once have I heard anyone care in the least about the watt-hours consumed during the brew process. "I really wish I could drink coffee at room temperature all the time and save a penny on electricity while doing it!" Someone will do the math, I'm sure it's not exactly a penny.
TL;DR: Aiming for a high-volume industrial goal, tone-deaf to coffee enthusiasts.
Actually, heating and pressurizing is limited by how much juice your electrical installation can pour out.
Someone get James Hoffmann on the line right now.
I will wait for his blind testing before homebrewing this one.
Might be a new meta for iced lattes.
But people want to drink coffee/espresso hot, not room-temperature. So you have to heat the water afterward anyway. I'm not seeing that much potential for energy savings here, unless you're comparing setups with large boilers inefficiently used for small amounts of coffee.
According to the article they see the main use for industrial scale production of coffee/espresso based drinks, in that regard it does make sense. For home use not so much even if there could be some niche market for cold espresso drinks at home, using less ice would allow for less dilution and faster than prepping and then refrigerate the coffee. I sometimes put concentrated ice coffee into my whey/oat shakes, but this is indeed very niche use even for me.
I have friend with a Jura coffeemaker.
Makes nice coffee, but I don’t think it’s worth the cost (but he has a lot of money, so it’s not a big deal for him).
I envision some fairly high-end kit, coming from this.
They explicitly mention large scale producers for mixed drinks as a massive target audience. E.g. iced coffee manufacturing will be heavily impacted, they would normally need to heat the liquid, extract the coffee and then cool it back down.
If I read it correctly, they did espresso and filter taste tests at room temperature (thought they don't state the exact temperature, and how they managed to brew filter coffee with the described setup). Overall the press release is somewhat misleading in what the goal is until the part you mention. If the focus is industrial production of cold, mixed coffee drinks I'd have expected more quantitative measurements instead of taste tests. Testing how well your coffee is extracted is pretty trivial with the right equipment.
> But people want to drink coffee/espresso hot
An awful lot of people drink iced espresso drinks these days. Room temperature (or below) brewing would make a big difference to the dilution in those drinks.
75% energy save to make a room temperature expresso. I am ok spending a bit more energy to have it warm.
I'm _very much_ a coffee nerd.
There's a semi-famous, super hipster cafe near me in Tokyo, that I sometimes go to.
Once, they had a special on the menu, when they give you a flat white, and a double shot of espresso on the side, with a thermometer hovering over the shot, with suggestions of tasting notes that you can get out from sips at different temperatures.
Now, that's generally very much a thing — things definitely taste differently based on the temperature (or maybe _they_ don't, but we _perceive_ them differently? distinction without a difference, I guess.).
The suggested temperature ranges were 51-40C; 40-30C, and 30-20C.
51-40 was great. 40-30 was getting weird, but still _interesting_, because you definitely got different notes.
But the 30-20 was terrible. That is absolutely too cool to enjoy a shot of espresso. I'm all for experimentation and doing weird things, but that was no longer riding the line of "not great but interesting" and went straight into "why would you ever do this" territory.
Cool! I noticed most of my Chinese friends drink cold or iced coffee. Undrinkable imho but yeah, there is def. a market.
It is intended for manufacturing canned iced lattes and similar, as stated in the article.
> The saving could be especially significant for companies who make coffee-based ready-to-drink products at industrial scale
It's not for you
Think of how cool you'll look with an oscilloscope on top of your coffee machine, though.
Awesome idea. I would love to try it. If that can also make my espresso routine easier I am up for it.
The crema looks like terrible, more like Nespresso, and having the coffee warm is kinda important.
But perhaps this can be used in the instant coffee industry or something.
>But perhaps this can be used in the instant coffee industry or something.
As stated in the article, the whole point is for use in ready-to-drink coffee manufacturing.
Could be useful for mass production of espresso-based drinks (like the ones sold at convenience stores), and possibly various foods like Tiramisu.
An average coffee shop's espresso machine might use $200/month of electricity, so even though the percent saving (75%) is high, it's off a base that's small relative to other costs; possibly too small to be enticing.
For certain styles of coffee, crema in espresso is not necessarily desired — it typically has a high concentration of more bitter flavor compounds.
If you're drinking light, floral and acidic coffees, it's been relatively "trendy" recently to skim the crema off before drinking it.
I don't bother with that, but pulling two shots and removing the crema from one of them and trying them side by side is an interesting sensory experience — I'd encourage you to try, at least once!
It is the GPT2 of espresso. Looks bad but idea is sound. There will be a GPT5.5 later on.
> having the coffee warm is kinda important.
Cold drip coffee is a thing, done well a very nice thing.
I like my Nespresso thank you very much.
And this is why you can't use "100 regular coffee drinkers" to judge the quality of the brewing method. Most people can't even taste (or care about) the difference between arabica and robusta beans or whether it's red or white wine.
Sure you can. You can absolutely use those 100 participants if your aim is to develop and market a process that can then be used to make a product for those same types of people. Samples generalise if your sample is representative, and in this case, for large commercial coffee extraction companies, third wave coffee aficionados are not in their target audience.
The product is moving into a different territory, though. I doubt these guys even know how to pull a proper espresso shot as a baseline for the test. I'm sure you can grind espresso coffee beans to a powder and just shake it until it achieves a flavor similar to espresso, but that doesn't mean the resulting drink can really compare to something that was brewed at the right temperature and pressure.
Technically you can also buy a bottle of grape juice from the grocery store, let it sit on the kitchen sink with a yeast lock for a few weeks and call it wine, and technically it even is, but it's also going to taste quite shitty.
> I doubt these guys even know how to pull a proper espresso shot as a baseline for the test.
You could just read the linked paper?
> Esp was prepared using a Sanremo Cube espresso machine. Brewing parameters were standardised following the supplier's guidelines: extraction time of 35 ± 3 s, pressure of 9 bar, and boiler temperature of 122 °C, with the corresponding group-head temperature of 94 ± 1 °C. A total of 21 g of ground coffee (GS = 2.6 ± 0.1; ∼262 μm) was placed in a ridged coffee basket and tamped using a constant-pressure tamper (MHW Flash Constant Pressure Tamper 2), applying 13.6 kg of force. The BR was reduced from 2 to 1.7 following the recommendations of the coffee roaster for better flavour (1 g of coffee grounds yielding 1.7 g of coffee brew).
1:1.7 is a bit short for my preferences (I like longer shots, usually aim for ~2.5); but otherwise that sure sounds like a pretty good double to me!
You're right. But I drink my espresso hot, so I don't quite see how it can compare : )
I jumped on this at first as well. But to be honest if their target demographic is industrial production of coffee like beverages (like those Star Bucks soda can ”coffees”), well then it might not be so bad. I was thinking that a lot of flavour compounds of espresso breaks down quite rapidly while the drink cools, so the method of cooling all drinks to equal temperatures could be enough to skew the results regardless, but again for commercial coffee based soft drinks this is already the case. Headline is a bit misleading though.
I like good quality coffee.
But I also need my coffee: I'll drink whatever quality coffee is being offered, as long as it's the best I can get that morning.
Considering the vibrations from those capsule machines it might not be so far off
[dead]
When you thought that coffee snobs couldn't get any worse...
...you discover frackuccino with cat processed beans: https://www.youtube.com/watch?v=rqw09I-BTvE
Civet coffee is the best! The production method not so much sadly :( Maybe they can create an artificial cat stomach?
Not even the baristas are safe. Technology really is coming for everyone.