Aerated coffee

I’ve another post coming on why I blog, but this reason deserved a post in its own right.  A few days ago Shaun dropped me an e-mail about the Vinturi.  He’d played with it a little bit and thought it was interesting, and thought it might be something that would interest me. I admit I was curious – so I grabbed one from the UK website.  (Clicking through may help explain the image above!)

As I write this I confess I know very little about the science of aerating wine – feel free to point me in any link-based directions!  I didn’t know if it was specific to wine/alcoholic beverages with very volatile fractions, or whether it would affect coffee too.  I’m rather lucky in having Anette who is very good at tasting things – so I gave her several different brews split into pairs of cups, one aerated and one not.  Each time she said one cup tasted noticeably better, and it was the aerated one. As I was the one conducting the tests I’m rather biased, so feel free to discount this – but I thought the aerated cup was sweeter and had better clarity.

One obvious explanation would be that the aeration cooled the coffee, so comparatively it was the easier cup to taste – I should probably check how much temperature is lost (though I did preheat the Vinturi before doing it).  I am sure a slightly cooler brew would have an advantage, and a noticeable one at that, over the same hotter brew of the same coffee.  Simply pouring into a cooler cup could well create an advantage.  However the use of aeration in wine – which, again, I don’t understand yet – does intrigue me.

Yesterday we dropped some espresso through it, and it was interesting.  We then brewed an americano, skimmed it (for this is what crema skimming was truly made for) and then aerated it.  It was the best american I think I’ve ever had. 1 Perhaps I simply wanted it to be.

I am well aware you could pull the “Emperors New Clothes” card on this one – but I still think it warrants a little attention.  If people can come up with some experiments that will isolate the aeration then I’d be willing to try them and perhaps open the doors at work to people who want to take part in a little experiment too.

I will keep playing with it, and report back after a bit of reading on the science (if any) behind it all…

  1. But I haven’t had that many, and I never really liked them to begin with!  ↩︎

23 Comments

  1. These types of posts are why I enjoy reading what you have to say. Questions, thoughts, and the challenge for someone to please attempt to prove it wrong (or right…)

    Carry on, Sir.

  2. I’ve definitely noticed differences with aeration. It came up first for me when I was trying to quickly make iced coffee from frenchpress the same way I make quick ice tea. I put the coffee in one steaming pitcher and then raised it high above another steaming pitcher and poured it in, then back to the original pitcher, back again etc. I do this when I make to order ice tea on bar, if you get in a rhythm and quickly pour it back and forth 5-6 times it drops the tea temperature way down and doesn’t melt the ice as much.

    When I did it with frenchpress (I believe it was a medium body yirg), I noticed even over ice that it seemed to sweeten and clarify the cup some compared to refrigerator cooled frenchpress. I tried just transferring between pitchers just twice and drank it still fairly hot, and it seemed to sweeten it and open up some of the normal frenchpress intensity. I haven’t done extensive controlled testing, but I definitely agree it’s worth looking into more.

  3. Out of curiousity, were you using the red wine or white wine aerator?

    …I’m wondering if you and Anette prefer your coffees to have softer tannins…and perhaps….pourover would be interesting through one of these (V60>Vinturi>Riedel ‘O’ Cab Sav). For my own palate, strong tannins alter my perception of other flavours & aromas quite strongly, so softening them my produce the clarity you mention in your case as well, reducing astringency.

    Do you perceive the Vinturi to be actually decreasing bitterness or increasing sweetness in the cup?

  4. I have a venturi and thought about trying it with coffee but chickened out thinking that if the coffee was too hot, it might damage it somehow. But I’ll certainly have to give it a try. Maybe bring it into the shop and do some blind cuppings of our own. I’ll share the results.

  5. I thing what you are noticing in the case of the americano/french press cup is the reduction of the free radicals, if you look at the physics behind the Vinturi devices, the decrease in pressure inside the device causes the increase in time for the mixing of air with the liquid, this not only causes drop in temperature but also changes the surface/body pH of the coffee, as the surface at which the interaction is taking place you are loosing or in other words interchanging the high energy free radicals with more stable forms of compounds. More stable the brew the lesser changes you will notice, like someone else was suggesting may be trying a pour over might give different results. Also may be measuring the pH of the cup before and after might show some interesting information. In the case of a pour over since the brew is exposed to air for a longer period you might not see that much of a difference in the cup. I guess we just transformed a simple cup of joe into a thesis defense idea. Love the work!!

  6. A year or two ago, I tried putting coffee through those cheapo “milk frother” things – you know, with the plunger and screen, that sometimes comes with stovetop moka pots – this was based on some forum post on CG where the poster claimed it improved coffee taste.

    I have to admit there was a bit of an improvement on the cup, but I put it off to the better mixing of a non-espresso brew and the cooling effect the rapid movement of the coffee had (coffee does need a bit of time to cool down!) But I didn’t notice enough of an improvement to pursue it – mind you, I don’t have Anette’s palate.

  7. I’ve got one on the way now. Will put it through its paces at the Wendelbar once it arrives.

  8. Interesting idea. Not sure about the chemistry involved but right after reading this, I brewed a cup using a siphon. Watching it I thought to myself, “does the draw down count as partial aeration?” Perhaps this is why I have always found siphon brews superior to other brewing methods?

  9. Quite an interesting thought for coffee. I used to run a cocktail bar and the reason for shaking aside from dilution was the aeration. With something like pineapple juice for example it would break down some of the acidity as well as create a smoother lighter texture which was much more pleasing to the pallete. SO the old “shaken not stirred” addage did exactly the same to the vodka martini. (aside from dilution again) it made the drink softer. Which is exatly why a cosmo is shaken – it softens the cranberry and lime to give a more gentle, softer mouth feel.

    Lee

  10. Hey James, I bought one of these for myself as a Christmas gift to me.. I’m pretty good to myself sometimes. Anyways, I like drinking wine, but the main purpose for buying it was to do exactly this, see the effects of aerating an espresso firstly and then secondly drip filter.. I found that both coffee’s when passed through the device were noticeable clearer, crisper and bigger on the nose. Like you I can’t explain why , but I spent most of my Christmas playing with this toy, using it to filter espresso through certain ingredients(pepper,salt,sugar, spices etc) just before it reached the little turbine funnel. It genuinely does pump air into the liquid, oxygenating the fluid and I guess opens it up for a bigger Olfactory sensation… It’s trickery, exaggerates the senses .

    I think it has plenty of potential with single origins etc and obviously the playground that is competition .

    Rob

  11. m’lissa muckerman owens says her father, a “water guy”, claims water is sweeter with more air. or maybe he said oxygen. you get the idea.

    if you’re concerned that the aerated coffee is benefitting from being cooler (a clear advantage, i agree), perhaps let both cool to a more stable temp..? say 110-120? but, you know, in your metric system.

    my only skeptical thought is that, assuming you didn’t boil the hell out of the water, fresh, cold water from the tap is quite aerated by design.

  12. So… How long would it take before we see the first aerating portafilter spouts and drip cones?

  13. I’m a big believer in letting a good bottle of aged wine ‘breathe’ before downing it… So I guess aerating makes sense… just hadn’t really thought of doing it with coffee.

    Having said that, I have for a while now, felt quite strongly about not letting my water boil when making my morning french press – I’m a romantic at heart!

    My theory behind this, quite similar to ryan’s comment earlier, is as follows – and someone please discredit me if I’m wrong – my wife would love that… Hahaha -

    Water is made up with Oxygen particles in it. When we boil water, these oxygen particle go a little crazy, and some of them are lost in the form of steam. So to my very unscientific little brain, the less oxygen particles in water, the less ‘sweet water’ taste we have. Ever drunk water from a waterfall, babbling brook, or dare I say it – the shower? The water tastes sweeter right?

    So if we’re taking a poll about whether aerating liquid can add to it’s taste, put me firmly down on the ‘YES, it can!’ side.

    Thanks for listening…

  14. This is an interesting article and as Bunn is revealing their new single cup brewing station, the Trifecta (code name bubbler) which uses a jet of air to agitate the grinds during the extraction, it makes me wonder what difference the amount of dissolved oxygen makes during the extraction versus oxygenating the coffee afterward on the way to the cup.

    I might have to try using a straw or an aquarium pump in my Clever Coffee Dripper to see for myself.

    -Chris

  15. Do you know of anyone who has used this on Tea? Since aeration is useful in “opening up” the tannins in wine one would think that Tea might undergo an interesting change with this.

  16. It might be interesting to try aerating our water as much as possible prior to brewing to (hopefully) reach the same end. This could lead to a new design for water towers and electric kettles, maybe useful for cuppings as well…

  17. I would like to see the CLIP video for this experiment because i may be doing it, if you have any video please post it or give some URL.

    i’m a beginner at barista and found your site very cool. thank for all knowledge you sharing.

  18. Interesting. It’s generally accepted in other forums that aeration of hot liquids is a no-no. Namely, brewing beer. Aeration above 27 C is called ‘hot side aeration’ and is known to negatively affect the taste. I’ve generally accepted this to most cooking / food applications, and have strayed away from aerated hot foods/beverages. It’d be interesting to see the affect at different temperatures, as well as time-based effects (tasting the cup immediately after aeration, then 5 minutes later, then 10).

  19. What i have found out is that aeration altered the pH of my brewed coffee.
    Perhaps this is because CO2 is trapped inside the coffee bean when it’s roasted. I know most of Co2 disperses into the atmosphere a couple of days after roasting but a small amount is still contained inside.
    This can be best seen when we brew coffee. We see CO2 escaping, bubbling out of the bloom. But i guess not all CO2 escapes though. It will be dissolved in water and form carbonic acid.
    By increasing the dissolved oxygen level in water, it should dispel more CO2 and will reduce the presence of carbonic acid and therefore raise the pH (slightly).

  20. Oh i should mention also that my aerated coffee tasted a bit sweeter and i think the coffee was better. But perhaps this is just my imagination.

  21. How to do that the right way :
    1. We need fresh tap water (Do not reboil it!)
    2.Boil the water as quickly as possible
    And you should get a cup of aerated coffee that has fuller and sweeter taste.

Submit a comment