Last week I made mozzarella cheese (not fermented) for the first time. After heating the milk and removing the curds, I microwaved the curds repeatedly until getting them to 135 degrees F, then formed the cheese. Last week's cheese was delicious.
I tried again today and the cheese turned out very "squeaky" in that its texture is kind of plasticky and it actually makes squeaking sounds when I chew it. This batch seems drier than the first batch as well.
My guess is that I either overworked or overheated the cheese. I ended up heating it to 135 degrees twice: it cooled down too much when I was working it, so I heated it again. I also heated it in longer bursts than I did the first time as I realized that it took quite a few 30 second bursts on my microwave to get the cheese to 135 degrees. Finally, I heated the cheese a bit too much on the last burst: it got to 138 degrees.
I can't tell which of the aspects I mentioned in the last paragraph are relevant to my issue. I'd rather not make poor cheese from another $5 gallon of milk...
Edit: I may have found the answer, posted below. Other insight into this is still appreciated. (as well as suggestions for how to fix the botched cheese)