There may have been a problem with my milk pH, Julie, but there was probably also something wrong with my process. A major issue was that I didn't use enough rennet. My temperatures got a little out of control, beyond my targets. There may be other factors.
The recipe and process are approximately as given in The Cheesemaker's Manual by Margaret Peters-Morris.
Here is a summary of my recipe, process, and observations:
4 gallons low-temperature pasteurized non-homogenized Jersey milk
3/4 tsp CaCL
3/4 tsp Rennet (but I know now that I measured it short, and probably used 1/2 tsp)
3/8 tsp MA 011
1/8 tsp TA 061
5 fresh habanero peppers
1 tsp red pepper flakes
1.5 tsp dried mixed jalepeno and serrano peppers
saturated brine
I removed the seeds from the habaneros and boiled them in a cup of water for 15 minutes. Then I strained out the seeds added the habaneros (cut in halves) and the dried peppers. I added a little more water and simmered those for 15 minutes. I poured the cold milk into my vat. My first mistake was that I forgot to take a pH reading of my milk at that point. I added the water from my peppers to the milk, stirred it, started heating the milk slowly. Then remembered that I hadn't gotten a pH reading. So I took a reading, and it measured 6.54 at 74.5°F. The expected pH of fresh milk is 6.6, so it was reading low.
All of my temperatures were taken with a Thermapen. I overshot my temperature target of 88°F degrees by .5°F, cut the fire, and added the culture, let sit 5 minutes, then stirred and took another pH reading. It had already dropped to 6.39. I also took the temperature again, and it had risen to 89.4°F. Either I hadn't stirred enough before and the milk was actually hotter than I read initially, or my vat, which has a thick aluminum cored stainless steel bottom, had continued to contribute heat to the milk after I shut off the fire. I may need to compensate for the temperature rise in the future.
I allowed the milk to ripen for 35 minutes. The recipe says 45 minutes, but I noticed that many people only go for 30 minutes. pH measured 6.36. That was much lower than my target of 6.5, and another reason why I decided not to let it ripen any further. It would have just continued to drop as the bacteria converted more lactose into lactic acid (or whatever it is that they do).
I added the rennet, 3/4 teaspoon. I used a new measuring spoon set that has a spoon labeled 3/4 tsp, 3.75ml. But when I later compared it to some of my other spoons I found it was closer to 1/2 teaspoon than to 3/4. If I had filled it to overbrimming full, it would have been closer to 3/4 tsp. I believe I need to get a syringe so I can be more accurate with this in the future.
Flocculation time, as measured by the spinning bowl test, was 22 minutes. That was longer than I targeted (e.g., 12 to 15 minutes). My rennet is very fresh, so that extended flocculation time is what prompted me to check my new measuring spoon capacity against my old ones.
I used a flocculation multiplier of 3.5 to determine optimum cutting time, so my total time before curd cutting came to 77 minutes. I waited the additional 55 minutes, tested for a clean break to confirm, and then cut the curd into 1/2 inch pieces. I let it rest for 10 minutes after cutting to heal the curds. Temperature was now 88°F exactly, and pH was 6.16, much lower than my target of 6.45 at this stage.
I raised the temperature slowly to 100°F over 42 minutes. I stirred very slowly and gently, almost continually for the first 15 minutes, and cut all the large curds I found to 1/2 inch size. I continued heating and stirring gently every three minutes until I hit the target temp. However, again, I overshot it slightly. After cutting the heat and stirring some more, I measured 101.4°F. I took a pH reading, but I forgot to write it down.
I let the curds settle for 25 minutes, then did a texture test. The curds seemed pretty squishy, but I thought they might be ready anyway. They held together pretty good and then separated easily. But they looked a little bigger than the pictures I'd seen of a Monterey Jack squeeze test, so I let them go another 10 minutes. Then I stirred and measured pH of 5.6. I believe that is way too low at draining time.
I drained the curds in a butter muslin-lined colander and mixed in the peppers by hand. I don't have any more pH readings from this point because my meter is the glass bulb type, not the flat electrode style, so I didn't figure I'd be able to get a good reading from the drained curds.
I hooped in a 6 inch diameter form and pressed at 8 pounds for 15 minutes. When I went to flip and redress, the entire cheese simply fell apart. The curds had not stuck together. So I refilled the form and pressed at 25 lb for 45 minutes. Then I flipped it over, redressed, and it was pretty crumbly. A couple of chunks fell off the edges, but it didn't completely fall apart again. I pressed at 50 pound for 6 hours, then I just increased the weight to 90 pounds and pressed another six hours.
When I removed the cheese from the form, it was clear that it had not knit well. There were small cracks everywhere, but the cheese didn't seem like it was going to fall apart again. It weighed 4 lb 2 oz, 1.86kg, so I brined it for 11 hours and 15 minutes, then turned it over and brined it another 11 hours 15 minutes. Total brining time was 22.5 hours. This was based on the guidelines in the recipe that said to brine for 12 hours per kilogram of cheese.
That's pretty much it. I'm a bit disappointed, but I'm going to try again. Next time with just two gallons of milk, and no peppers. I want to see if I can do a proper plain Jack. I'll be watching my pH more closely, and I'm going to salt the curds before hooping, like you do with a cheddar. The salt should also slow down the bacteria and the resulting pH drop. I'm going to use the right amount of rennet, and try to keep the curds warm before hooping and while pressing.
I'll age it anyway, but I don't expect much from it.
