help, rennet died, and now my milk won't make ricotta

[l4tte]

Tried making cheese using 2% milk I cultured with buttermilk. Heated it to 90°F, added rennet (twice!), but it totally failed, there's zero curds after two hours. I'm guessing the rennet is dead.

So, I tried to save the batch by making ricotta. I heated the milk to 185°F and dumped in the salt and lemon (acid), but still no curds, even after holding the temperature for 20 minutes.
What happen here? Why did the ricotta attempt fail, too? Shouldn't this milk still work with heat and acid, even if the rennet was bad? can this milk be saved?

 

[Alan]

Sorry that batch didn’t work out. Ultra-pasteurized milk is a common issue and can block curdling completely. Did the milk label say UHT or high-temp pasteurized?

 

[Cheesy 4dam]

Hi @l4tte, your ricotta attempt failed has nothing to do with the bad rennet. it just means your milk was missing the key ingredient needed for ricotta. yeah, it need whey protein!

Ricotta means 'recooked' because it's traditionally made by curdling the leftover whey after you've made a cheese like mozzarella or Gouda.
When you used 2% milk, you pulled all the casein (the main curd protein) out during your culturing process. The only proteins left are the whey proteins, but you didn't have enough of them concentrated in the milk to form a solid mass when you heated and acidified it. Ricotta needs concentrated whey, not just milk!

 

[l4tte]

If you want to make ricotta, you must start by making a different cheese first (like mozzarella or paneer) and then use the leftover greenish yellow liquid (the whey) for your ricotta attempt. You can't skip the first step, just saying