Bubbles arise in foam

(Kate Seward) #1

I recently opened a cafe, and we’re struggling with our foam bubbling shortly after pouring a drink.

We’re working on a 2-group, la Marzocco Linea. We will start with perfect milk with glossy micro-foam, and pour beautiful latte art, just to find it start to bubble even before a customer receives their beverage.

Sugars do seem to help stabilize it a bit better, so our mochas will hold well.

I’ve tested multiple types of (dairy) milks, steam wand tips, steam pressure, and am struggling to get to the bottom of this. I am wondering if it is the acidity in our espresso? We are currently using a Guatemala/washed Ethiopia that is a light to medium roast.

Has anyone experienced this before, or does anyone know of some research available that talks about this?


(Ben Cordova) #2

Hi Kate, we are using the same machine and I have to believe its your coffee. Im sure its great but what else could it be. If your are steaming great micro foam and pouring latte art then its not the milk? Does it happen in ceramic AND paper?

(Ben Cordova) #3

What are your grams in and grams out and brew time?

(Kate Seward) #5

Thanks for the response Ben. What is your steam pressure set at? Yes, it’s ceramic and paper, and our ESP ratios are currently at 1:1.5 and 1:2 .

(Wesley Griffin) #6

I find that if you can finish foaming milk before the milk temperature reaches body temperature then the foam is more stable for longer, holding it’s glossiness and maintaining latte art. If you’re getting a nice, glossy micro-foam I’d keep foaming the milk how you’re currently doing it, but try to finish foaming before the temperature of the pitcher feels “neutral” (not hotter than your hand, not cooler). After that point just get a good roll/whirlpool going to integrate the foam into the rest of the milk well. I find that foam introduced after body temperature doesn’t hold well and ends up bubbling pretty shortly after pouring the drink.

I find that does the trick for me. Not sure if it’s totally scientific, but I haven’t found any other solutions to that problem.

(Kate Seward) #7

Thanks for the response Wesley. We’ve only been having this problem at our new cafe which is using new espresso and new equipment, so I’m assuming it’s something to do with one of those??? I haven’t run into this before in my career, so it’s is really boggling my mind. I’ll definitely keep an eye on stretching too late in the game though- thank you!

Kate Seward
Form & Function
Coffee // Roasting // Supply


511 W Broad St. Boise, ID 83702

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(Shawn Thacker) #8

…this is the thing that has improved my milk texture more than anything else. I used to try to increase the volume too much by aerating for too long when steaming. Introducing air early and then dipping below the surface to ‘swirl’ is a great tip here! :+1: