Connie, the flocculation approach is preferred to making time-based decisions because the cheese moisture content is one of the core indicators of final cheese quality and character (the other being PF ratio). If you constantly make decisions based on time alone, and use the same time markers every time, your cheeses will have great variability because the milk differs.
The moisture is so important because it helps to determine the rate of catabolism of all sorts of stuff. It determines the rate of proteolysis (for proteins to break up, the availability of water is a key aspect of the rate of reaction), it helps to determine the rate of sugar glycolysis, and it helps to determine all the complex aroma and flavor forming compounds.
Case in point, for cheddar, I think I've mentioned this before. You get a 35% moisture cheddar, and you can have a prize winning cheese in 2-3 years. You get a 37% cheddar, and in 2-3 years, it'll be sharp, with some slight bitter and sulfur notes, but it's won't have that very complex flavor associated with the best cheddars. This is using identical makes, but targetting different moisture content, and a 2-5F difference in cooler temps.
Anyway, the way flocculation works is that it is the longer a milk gel sits after renneting, the stronger it gets, and the more water it tends to retain. And the smaller the curd size, the more surface area there is, and the more whey can be released. The other way you control moisture is by heating the curd and through agitation. So you use all those things in combination to hit a final moisture target.
There's plenty of other info on the technical details of floc and how it works with the two-phase, rennet-induced coagulation, so there's no need to talk about it again, but keep all those things in mind in terms of what you're after is a final moisture target. And you control that by:
- Length of time from renetting to cutting, as determined by floc to take into account milk variability
- Curd size (more curds = more surface area)
And then for rate of whey expulsion and degree of expulsion:
- Agitation (stir/rest schedule. More stirring = more curd collisions = faster syneresis)
- Heat schedule (higher heat = faster syneresis)
Francois, I was trying to get to the point, poorly, that with a grana-type cheese, you do cut it, but to get all the curd bits to be like rice kernels, it does take a little time. And during that time, it's kind of like having an integrated heal in the process. Kind of like for large vats, you start cutting, and by the time you're done cutting, the curds have had a chance to firm up a little.
