Why does my Velveeta queso dip get clumpier the longer it stays in the microwave? I had a bizarre experience with Velveeta this past weekend and was hoping you all could help me out.

I bought a block of Velveeta and some Rotel canned tomatoes to make a queso dip.  I microwaved the dip for about 8 minutes total (taking out after 5 to stir.)  After the 8 minutes were up, I started stirring the queso and noticed that the cheese was still clumpy.

So, I stuck the queso back in the microwave for four more minutes and when I took it out, it was worse than before.

This has never happened before, usually when it gets clumpy, you can just throw it in to the microwave for a little while longer and it comes out nice.

What happened here?  Do some foods become clumpy when they are cooked too long?  Could the Velveeta have been bad?  I've made this several times, and I don't think I did anything different here.
From what you're describing, I think the cheese (or cheese-like substance, in this case) 'broke' ... that is, the oil separated out of it.

I'd recommend:


Don't melt it at full power
Stir it multiple times during melting
Melt the cheese (or "cheese-food") seperately, then add the tomatoes, so the tomatoes don't get hot, causing uneven heating.


I'm not sure if there's a good way to recover cheese once it's broken.  Some starch will help keep dairy from breaking in the first place, but I don't think it'd help you in this  particular case.