Batch 5: Slowly I heated the milk with citric acid to 90F and added the rennet. After waiting 5 minutes I checked the milk. Oh My! The curds cut cleanly with a knife! We had a clean break! I followed the rest of the recipe and microwaved the curds. Then I killed it in the microwave by heating it too much. Oh I was so close! I think the bowl used was too hot and the butter fat in the cheese melted into a pool of once was cheese curds. It tasted bad, so it got tossed into the trash.
So close… Still one gallon of milk left!
Batch 6: Slowly the milk heated to 90F and added the rennet and covered for 5 minutes. The curds were soft so I let is set another 10 checking at the five minute mark. This was just like the bad Mozzarella curds from earlier batches.
Conclusion: Finally I have decided that the problem was the Trader Joe’s Milk. We had two batches of milk in the original 5 gallon purchase based on expiration date. I was able to go back and confirm that the milk in batch 5, that made good curds was different than Batch 6. My guess is that the bad milk was Ultra Pasteurized and not HIST Pasteurized.
I called Trader Joe’s prior to my milk purchase to verify the pasteurization used in their milk. They told me the specifics of the pasteurization used in their milk, although I did not write it down I thought it was the HIST process. I assume that TJ’s does not have a way to verify the actual process used on a day by day process.
The plan for next batches is to get milk with a dairy brand on it. A dairy that is proud of their products like Alta Dena or Rockview Family Farms.