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Cold brew coffee in 3 minutes using acoustic cavitation

unsw.edu.au

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Re: Cold brew coffee in 3 minutes using acoustic cavitation

#51

Post by fallat »

iancmceachern wrote: post #39
fallat wrote: post #35

Earlier quoted context omitted.

What? I went on Aliexpress and found a 40KHz transducer for $40. You can 3D print the attachment, can't you?

A woofer from AliExpress is not a speaker with amp you can use for University level audio work. I expect they used something like these: https://www.emerson.com/en-us/automation/branson You cannot 3d print anything in the ultrasonic chain, they need to be machined from specific metal, that's why the horns cost so much.

I looked up "transducer" and it seems to be what you'd need. But! You seem to have found where I was wrong: the horn. The horn seems to be the actual expensive part here. They could start a business I guess selling these en-masse. If anyone has any ideas how a maker could create this within reason please reply.

Re: Cold brew coffee in 3 minutes using acoustic cavitation

#52

Post by parineum »

iancmceachern wrote: post #39
fallat wrote: post #35

Earlier quoted context omitted.

What? I went on Aliexpress and found a 40KHz transducer for $40. You can 3D print the attachment, can't you?

A woofer from AliExpress is not a speaker with amp you can use for University level audio work. I expect they used something like these: https://www.emerson.com/en-us/automation/branson You cannot 3d print anything in the ultrasonic chain, they need to be machined from specific metal, that's why the horns cost so much.

> A woofer from AliExpress is not a speaker with amp you can use for University level audio work.

We're talking about coffee here...

Re: Cold brew coffee in 3 minutes using acoustic cavitation

#53

Post by csmpltn »

dahart wrote: post #17

Recently I discovered that many coffee shops, maybe half in my sampling of a couple dozen in different cities, are selling cold coffee (brewed hot, then refrigerated) under the name cold brew, and even the ones that actually cold-brew them seem to be under the impression that it needs to be served cold. I was laughed at in one hipster joint for asking for a steamed or warmed cold-brew, and another one initially refus…

This is an extreme form of coffee hipsterism. “Cold brew, but steamed please”. Brother, this is starting to get ridiculous.

Re: Cold brew coffee in 3 minutes using acoustic cavitation

#54

Post by the_optimist »

dahart wrote: post #17

Recently I discovered that many coffee shops, maybe half in my sampling of a couple dozen in different cities, are selling cold coffee (brewed hot, then refrigerated) under the name cold brew, and even the ones that actually cold-brew them seem to be under the impression that it needs to be served cold. I was laughed at in one hipster joint for asking for a steamed or warmed cold-brew, and another one initially refus…

“Old Brew” can be more valuable. You must check the vintage and terrioir.

Re: Cold brew coffee in 3 minutes using acoustic cavitation

#55

Post by bananskalhalk »

bobthepanda wrote: post #50
opwieurposiu wrote: post #34

Earlier quoted context omitted.

At my friends coffee shop they make cold brew with an elaborate laboratory glassware setup that drips ice-water through a filter. Looks pretty neat and sciencey. They got 4 of these devices running all the time in the back room. I was telling him all the other shops in town just fake it, he should put one of the devices out front so people can see his cold-brew is for real.

To be fair all you need to actually make cold brew is a pitcher and a cheesecloth or some other filter. The absence of an apparatus does not make it fake.

Chilling warm brewed coffee is definitely faking it. And I presume all places selling "cold brew" is faking it so this guy is losing money by not showing off doing real cold brew with his apparatus.

Re: Cold brew coffee in 3 minutes using acoustic cavitation

#56

Post by antonchekhov »

New startup idea: manufacture a hard-plastic spiky attachment, shaped like a tubular hair-brush that I can simply screw onto the base of my Sonicare toothbrush, then stand upside down into the brewing carafe of my Oxo cold-brew setup. The Sonicare's built-in 2 minute timer may have to be activated twice, for a full brew.

Re: Cold brew coffee in 3 minutes using acoustic cavitation

#57

Post by kurthr »

dahart wrote: post #44
vallode wrote: post #27

Earlier quoted context omitted.

The paper[1] seems to imply agitation is exactly what this method is promoting: "Furthermore, acoustic streaming induced greater mixing and enhanced mass transfer during brewing.". I assume the 100W of ultrasonic energy would be pretty hard to reproduce by just shaking your cold brew container though! [1]: https://www.sciencedirect.com/science/article/pii/S135041772...

Very interesting, and I missed the 100W bit, thanks! Yeah that would be really hard to do by hand for 2 minutes. Maybe Guinness records needs to see who can shake their cold brew hardest/longest. So this begs further questions for me, like can I shake with 10W for 30 minutes, or 10 minutes, or…? Does the frequency matter? Can we use one of those chem lab agitator machines to cold brew?

I find it interesting that 100W for ~120 seconds is ~0.3kcal which for a 100ml cup is ~3C. They are right at the limit of power to flow rate. Much faster flow and presumably the cavitation wouldn't "brew" enough, while much slower and it would warm up the coffee noticeably. I'm doubtful the frequency matters much if the cavitation is what is causing the mixing since those are just bubbles emerging and popping, but the efficiency of coupling from ultrasonic wand to liquid could change a lot.

Since you could presumably put 2 of these in parallel and have 2x100ml cups in 2min with 200W without changing the recipe (or 1 cup in half the time), this seems pretty scalable with increased cost and area.

Unagitated cold brew is in the 10hour region, but with agitation/pump through it seems like you can do 8 cups in 20min which is almost as fast as the cavitation method. I suspect the grind size starts having really big effects here.

https://instantpot.com/products/instant-cold-brewer

Re: Cold brew coffee in 3 minutes using acoustic cavitation

#58

Post by ada1981 »

lamename wrote: post #32
dahart wrote: post #17

Recently I discovered that many coffee shops, maybe half in my sampling of a couple dozen in different cities, are selling cold coffee (brewed hot, then refrigerated) under the name cold brew, and even the ones that actually cold-brew them seem to be under the impression that it needs to be served cold. I was laughed at in one hipster joint for asking for a steamed or warmed cold-brew, and another one initially refus…

Thank you for saying this. When cold brew first came out, it was promoted as a brewing process that resulted in smoother (I'm guessing lower acidity) tasting coffee. Heating it up seemed natural, and its use in iced coffee seemed simply opportunistic. (In my experience at least). Then it quickly caught on as a novelty, with nitro et al, and when I tell people I drink cold brew warmed I get looks of confusion or turne…

The more complex, expensive and counter intuitive your morning coffee, the better!

90% of the experience is looking cool!

Re: Cold brew coffee in 3 minutes using acoustic cavitation

#59

Post by beefman »

A few years ago there was a crowdfunded instant cold brew machine based on acoustic cavitation called Osma.[1] I don't think it's still in production. I met the founder during testing at Chromatic Coffee in San Jose, and took delivery of one of the first units. Cool concept, but it didn't work very well

[1] https://www.engadget.com/osma-pro-cold-brew-coffee-machine-r...

Re: Cold brew coffee in 3 minutes using acoustic cavitation

#60

Post by nkrisc »

csmpltn wrote: post #53
dahart wrote: post #17

Recently I discovered that many coffee shops, maybe half in my sampling of a couple dozen in different cities, are selling cold coffee (brewed hot, then refrigerated) under the name cold brew, and even the ones that actually cold-brew them seem to be under the impression that it needs to be served cold. I was laughed at in one hipster joint for asking for a steamed or warmed cold-brew, and another one initially refus…

This is an extreme form of coffee hipsterism. “Cold brew, but steamed please”. Brother, this is starting to get ridiculous.

It’s no different than drinking an iced coffee drink that was made from coffee brewed traditionally.
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