Hi it's an old post but I thought it would be of value
1. Curd cooked too hot?
That does contribute however, there are two other parts to this
a. too hot - this will dry the curds - The pH is probably more a contributor here. However, once you get over the scalding temp of the culture you kill the culture and you no longer create lactic acid. Too much lactic acid removes the calcium from the curds - making the end result crumbly. But yes it would contribute.
b. heat to target temp too fast - will actually "case harden" the outside of the curds hence, trapping whey in the curds with quickly over acidify.
2. Wrong rennet amount?
a. Possible but you would have to seriously add too much. if you use the flocculation method you could possibly cut the curd sooner and still have sufficient moisture in the cheese.
3. Dry cave?
a. this depends - if your rinds are natural then yes, but you will see them drying and cracking so that should be easily countered.
4. pH problem?
a. absolutely see 1 and 2 above. A good pH meter will be invaluable in countering
Another thing that causes a crumbly centre is not turning your cheese - especially when they are young.
hope that helps
-- Mal
