# Bubbling latte art?



## Davnt (Mar 27, 2015)

So, I woke up, did my usual routine and this happened? Any idea to what caused this? Seems like everything was fine and about 10 seconds after pouring latte art bubbles started to appear, not on the art itself though?

Anyone have a rough idea?


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## glevum (Apr 4, 2013)

Just the way some coffee beans react to the milk.Some beans do that even when they have been fully rested (de- gased), some don't. Some beans like monsooned malabar seem never to bubble with milk even after a couple of days post roast.


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## glevum (Apr 4, 2013)

Nice art by the way


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## DoubleShot (Apr 23, 2014)

I've noticed this happens the longer you've let the drink sit there after pouring the steamed milk. Has taken longer than 10 seconds though, more like minutes later. So could well vary depending on beans used?

There is a scientific explanation but I can't remember it off the top of my head?


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## Dylan (Dec 5, 2011)

From memory, I think a few months back a similar thread concluded to some extent that it was to do with lighter roasts.


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## The Systemic Kid (Nov 23, 2012)

DoubleShot said:


> I've noticed this happens the longer you've let the drink sit there after pouring the steamed milk. Has taken longer than 10 seconds though, more like minutes later. So could well vary depending on beans used?
> 
> There is a scientific explanation but I can't remember it off the top of my head?


The acidity - more prevalent in lighter roasts - curdles the milk and as it does so, creates bubbles.


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## jeebsy (May 5, 2013)

The Systemic Kid said:


> The acidity - more prevalent in lighter roasts - curdles the milk and as it does so, creates bubbles.


Does coffee we perceive to have an acidic taste actually have a lower pH?


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## glevum (Apr 4, 2013)

Had a bag of Rave Sig' last year which was medium / dark. Whole 1KG bag made milk bubble like an aero bar.


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## Dylan (Dec 5, 2011)

The Systemic Kid said:


> The acidity - more prevalent in lighter roasts - curdles the milk and as it does so, creates bubbles.


I have had curdled milk from lemon, and I can say, thankfully, I have never had a coffee with anything resembling it.

Curdled milk makes you feel seriously unwell and often makes you throw up, are you sure this is whats happening?


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## jeebsy (May 5, 2013)

I don't think it's that. Maybe co2 or something but there was a post on here last year about how it tended to happen when the shot was stopped at a certain point.


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## Davnt (Mar 27, 2015)

glevum said:


> Just the way some coffee beans react to the milk.Some beans do that even when they have been fully rested (de- gased), some don't. Some beans like monsooned malabar seem never to bubble with milk even after a couple of days post roast.





glevum said:


> Nice art by the way


Haha thanks! It's one of my better ones so far, probably because it's friday











Dylan said:


> From memory, I think a few months back a similar thread concluded to some extent that it was to do with lighter roasts.





The Systemic Kid said:


> The acidity - more prevalent in lighter roasts - curdles the milk and as it does so, creates bubbles.


I actually just went to check what I just chucked in, YEP.

I just opened, what now happen to be my last bag of beans. Which apparently is Rave's Ethiopia Sidamo Wottona Boltuma. I actually thought I had a blend as my last


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## DoubleShot (Apr 23, 2014)

Seem to recall someone commenting on one of the latte art competition threads, asking what was with all the bubbles in the crema. co2 from the coffee reacting with the air or something in the milk?


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## Has Bean (Sep 12, 2014)

jeebsy said:


> Does coffee we perceive to have an acidic taste actually have a lower pH?


The more you roast something the lower the PH (more 'acidic')


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## jeebsy (May 5, 2013)

So if the level of roast theory was correct dark roasts would bubble more?


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## glevum (Apr 4, 2013)

Dont know if its anything to do with it, darker beans that produce a lot of static ie MM & Suarez never react with milk even with a very short rest period. I find these 2 beans great for latte art.


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## DoubleShot (Apr 23, 2014)

glevum said:


> Dont know if its anything to do with it, darker beans that produce a lot of static ie MM & Suarez never react with milk even with a very short rest period. I find these 2 beans great for latte art.


The darkness of the crema in a lot of your pours is bordering on a black hole...looks awesome!


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## glevum (Apr 4, 2013)

I only use skimmed & semi, perhaps the fat in whole milk reacts totally different.


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## DoubleShot (Apr 23, 2014)

Up until last week, I had only ever used semi-skimmed but thought I'd give whole milk a shot after reading comments from others that it froths better. As yet haven't done side by side tests yet to see if my findings are the same. There is a taste difference especially as I stopped using whole milk around 1989!


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## glevum (Apr 4, 2013)

Whole milk makes better micofoam. It does my middle aged spread no good so have not used it in donkeys!


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## stevogums (May 8, 2013)

Get this quite a lot..

Makes it look even tastier i think.

Superb Art by the way


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## garydyke1 (Mar 9, 2011)

jeebsy said:


> So if the level of roast theory was correct dark roasts would bubble more?


The bubbling IMO is down to gas exchange. Lighter roasts are denser , contain more 'stuff', and give off c02 at a slower rate.

Darker roasts have more c02 driven off during roasting and you'll note the bags expand rapidly immediately after roasting.

It seems to vary coffee to coffee.


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## DoubleShot (Apr 23, 2014)

And there we have it folks, wot garydyke1 said.


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