I made cheese a few times, years ago. I decided to try it again, and I started with some basic vinegar/lemon juice cheeses like Feta- all went well.

I then tried to make a hard cheese with rennet. After several failures I learned that the rennet was ruined because I was storing it in the freezer. So, I ordered liquid rennet on ebay and it was shipped from the UK. I also received some cheese starter culture ('Pima') from a local source. The Pima is fine, and an overnight stint on the counter gives me a gallon of yogurt.

However, even with the new liquid rennet (diluted in a small amount of bottled water, not tap), I'm not getting any additional firming to allow me to make the cheese. I'm hoping someone here can give me some ideas of what I'm doing wrong. Here is everything I can think of, but it isn't all testable.

* The milk is in a teflon-coated heavy (steel?) pot, because my only other large pot is aluminum. I couldn't find any evidence that teflon was a problem.

* I stir the rennet in with a wooden spoon

* I don't know if there is any chance that the rennet froze during shipping from the UK?

* I don't know if the Pima might interfere with the rennet activity?

* I haven't yet gotten calcium chloride to prepare the milk, since I didn't have any trouble with the acid-based cheeses.

* I use storebought whole milk, because I don't have access to affordable raw milk.

I'd really like to make a few small batches of cheese, so I'm open to any/all suggestions.

Thank you!

Keith