How to stop soy milk curdling in coffee

I'm no a fan of cows milk, it gives me a bad chest, full of phlem, and that's not to nice for those working and living with me.

Why Soya Milk curdles!

I've heard 2 theories about why soya milk curdles in coffee, but not tea, I cant vouch for why it doesn't curdle in tea as I like my tea black so have never been tempted to put milk in it but coffee, I prefer white. The first theory is that soy milk curdles in coffee because of the acid content of coffee. The second is that its because of the heat difference between the coffee having just been boiled and the Soy milk coming from the fridge.

The way I stop my Soy milk from turning to tofu in my coffee is to pop it in a Pyrex dish and put it in the microwave for 60 seconds. I have found that if I heat it for to long it actually gets hotter then the coffee and it still curdles anyway.

Some soya milks fair better then others in my opinion and its not always the more expensive ones that do best. Also I have heard that the Tesco's home brand soya milk is actually organic anyway.

I don't recall if oat milk or rice milk curdled if not heated, but they are often twice the price so I probably wont get around to trying them anyway.