can hot coffee curdle milk?!

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i'm a bit of a coffee connoisseur and no one can really make coffee to perfection for me so I normally make it myself. The only time my milk has ever curdled is when the milk is getting old. I'm fussy with buying milk and do like the full cream fresh milk and always look at the use by date. I add milk to soups and pasta dishes and never get curdled milk. Also make sure the water has been run from the tap for a few seconds before putting the water in the kettle . don't use old water.

The curdling you see is most likely do to the acidity of the coffee. Milk protein will denature at low pH. That's how cheese is made. The only thing I can suggest (and I don't know if it will work) is to try real cream which has a lot less casein or some of those artificial whiteners.

I'm not so sure that temperature has a lot to do with it, since milk and cream are pasteurized at temperatures a lot higher than your coffee.

PhD Food Chemistry and Nutrition

getting any milk too hot will cause the proteins in it to have a curdled appearance but it does not taste soured as it is NOT soured. It only looks that way.
Thats also why you cannot use milk in cream soups because it will look awful.
Heating it before hand will have no effect. IT will only curdle that much faster when you add it to your espresso.

The only time I've had milk/cream curdle in hot coffee is when the milk is on the verge of going bad. Same with soup or any other hot liquid. Your nose knows, next time it happens smell the milk, I'm willing to bet that it will be slightly "off" not sour yet but getting close.

No.