Flavored syrups curdling milk in coffee-based beverages

[DougL]

I've been using Monin and Routin flavored syrups for my lattes, and I'm disappointed that they often curdle the milk. It's the acidity. Now, Monin says that only their citrus flavor might do that, but that's not the case. One suggestion is to mix the syrup with the coffee before adding the milk, instead of adding the syrup directly to the milk, but that seems to curdle the milk as well. So, what's the solution? I'm tempted to try adding a pinch of baking soda to the cup to deacidify, but I'm concerned that will impart a yucky flavor.

[scott123]

I know a couple people who have played around with pH meters.  It was with dough, and the results seemed a bit mixed, but I think, for liquids, they might give you a good idea of the pH you're dealing with- for both the syrups AND the coffee.  

 

Milkfat is a stabilizer, making skim the most vulnerable, with heavy cream being the least prone to curdling. One thing you might consider is upping the milkfat percentage.  Darker coffee roasts are also less acidic.

 

All of the flavored syrups have to be shelf stable at room temp for a very long time.  To achieve this, acids are pretty much always gong to be one of the preservation players.

What flavors are you adding?  There might be a way of achieving these notes without the syrup.  For instance, citrus zest gives you plenty of citrus-y flavor, with much less acid.

Dutch cocoa has been 'Dutched' with potassium carbonate. Dutch cocoa, to me, doesn't taste 'yucky.'  I think the problem you might run into with baking soda, is that you might be introducing a bit of a salty flavor.  This is just a wild guess, but, I think you might get a cleaner taste profile using less of a stronger base, like food grade lye.  

 

Do you have any leeway over the temperature of the ingredients?  Maybe if you combine them when it's a little less piping hot, they'll be less prone to curdle.

 

One last factor- fresh milk is harder to curdle.  Not necessarily from the farm (you want ultra pasteurized/homogenized), but a brand new, unopened jug of whole milk might help a bit.