I'm experimenting with some conacado Dominican Republic at home, and after grinding for 24 hours I had super low viscosity (almost like water) with a super-small micron size. After adding sugar (30% to make a 70% bar) and grinding for another 24 hours, my micron size came back down to normal levels but my temp had shot up to 124F and the chocolate became super viscous and was pulling from the bottom of the grinder. I wanted to conch another day or so but I was worried the chocolate would seize up the machine, so I pulled it from the grinder and tempered and molded it. It has an astringent quality that I think conching for another day or so would've helped.
I was using a small batch (about 1.5lbs) in a tabletop grinder. Was I adding sugar too early? Is there anything I can do temperature-wise? I really don't want to add cocoa butter if I can avoid it. I can also provide pictures if that helps.
I would suggest The Science of Chocolate by Stephen T Beckett. It has a lot of useful information at a decent price.
It is my understanding that the longer you grind, the more fat is released from cocoa particles, which will reduce viscosity. Whether that applies to your case I have no idea, but perhaps 24 hours with such a small batch is too long, but that also depends on getting a good bean and hitting the roast right.
The Conacado beans are normally well fermented but quite acidic. So you would need to roast them adequately and than grind them for the first 12 hours (we roast at 130 degrees C for around 45 minutes, using a ball roast). During this first stage additional heat could be added in order to reduce the acidity further. The cocoa mass than reaches a 75 degrees C. After this stage you can (should) add some extra cocoa butter (3-5%) and than add the sugar, grind for an extra 2 days and you'll have a super chocolate.
Wow thank you so much for specific roasting times/temps!
Depending on what kind of grinder you are using, excessive grinding will exponentially increase the aggregate surface area of the particles in the chocolate. When this happens, there can be insufficient cocoa butter to fully coat all of the particles --- this results in a significant viscosity increase. As the viscosity increases, the amount of horsepower energy converted into heat goes up, driving up the temperature of the chocolate. Remember, when you measure micron size, you are just defining the largest particle in the chocolate --- all of the other particles are smaller than the micron measurement. Therefore, micron readings don't tell you anything about the particle size distribution. Excessive ground chocolate will also have a cloying sensation in the mouth as the very small particles actually plug up / get stuck in pores of the tongue.
Very interesting. So adding cocoa butter will keep viscosity down. How can you tell if you're grinding excessively?