Fresh milk curdles when added to hot coffee and tea Came in to work this morning and made a round of coffees, the same as yesterday.

To freshly washed and fully rinsed mugs, I added instant coffee, and the milk then filled with boiling water and the milk instantly curdled and all the bits floated to the surface.

Thinking it was just bad milk (the milk didn't smell off at all but I remember seeing it sat on the side at some point yesterday) I bought fresh milk and repeated. The same thing happened.

We are using the same kettle as yesterday, the same mugs, the same instant coffee.

To be sure it was the milk, I made a coffee with just coffee and water, it was fine, I then added the milk and it curdled.

To eliminate bad luck with 2 different jugs of milk, we've poured the milk into a glass to inspect and drank it and it is fine from both milk jugs.

Please help, I had a few beers last night and need my coffee!
Boil the milk on its own in a clean/rinsed container (microwave).  If it curdles, it's the milk. 

Otherwise either there is a decalcifying agent in the kettle or something in the coffeee is making it too acidic.  It takes very little, after decalcification, we usually have to pass about a gallon of water through the coffee machine before the steam wand stops curdling milk. 

If you're in a jam, boil your water in a cup in the microwave and avoid the kettle.