A customer asks: I’ve been making cheese successfully for quite a while now. But, all of a sudden, right after its done, it starts to grow into an ugly blob and smells awful. Is it contaminated and bad? Did I do something wrong?
Jerri’s answer: Great question! You must be baking homemade bread at the same time, or near the time you’re making cheese. The yeast used for making bread gets in the air no matter what you do.
Here’s the solution: Instead of heating the milk first and then adding cheese culture, add the culture while the milk is still cold. Then heat the milk to the start temperature and continue with the recipe as usual.
There is competition between the bread yeast and the bacterial culture. When you heat the milk first, the yeast grows fast and kills off the bacterial culture when you add it to the milk. But when you add the bacterial culture to cold milk, the culture starts to grow right away; and then it can overcome the yeast and kill it.
And, by the way, that yeasty blob of cheese won’t hurt you if you eat it, but it’s very unappetizing and it tastes awful.