🌱You’ve heard of it, seen it, and hopefully not served or drunk it. Soy curdle is real.
Soy milk curdles because espresso is really acidic. That’s not changing any time soon, but there are a number of tips and tricks to mitigate the sadness.
If you’re down with a little bit of chemistry:
Dilute some calcium chloride (or other food-grade buffer) in water and pour a little in the soy milk before you steam it. This will pretty much eliminate the curdle. You’re welcome!
If you’re not down with additives:
Add less air to the milk when steaming. The less bubbles, the less likely it is to curdle. Any curdle that does occur will create a layer of faux “head” on the drink that looks like foam.
Steam the milk to a lower temperature. If this isn’t a possibility, preheat the cups so they suck less heat from the drink.
If you still want lots of texture in the milk:
Pour really really fast. The faster your pour the more quickly the espresso is diluted before it has a chance to curdle the milk. Don’t be dainty - smash 80% of the milk into the cup as quickly as you can, then pour your latte art.