roll refining

Hello, can someone tell me if it is required to pre refine nibs and sugar prior to running through a three roll refiner (e.g., one with 6 x 12 rolls)? If so, what is the desired particle size for the paste prior to feeding the refiner?

I realize there are likely many different models with differing capabilities, so I just want to know what is most common for small-ish roll refiners, assuming I'd like my final particle size to be in the neighborhood of 25 microns.

I'm considering switching, and I have a mill to pre grind the nibs, but not the granulated sugar (crystal size is 0.3 - 0.8 mm).

Thanks

Is it required? No. However, most set ups that have a refiner configuration do it opposite of what you suggest - i.e., there is a benefit to running it first through your pre refiner ( the one with 3 rollers), and then running it through the full 5 roll refiner. The reason is that doing so creates a more even particle size distribution, and you get less fine particles, which helps with viscosity control. your nibs won't go through a refiner very efficivly, so you'd want a hammer mill or some other way of milling the nibs into a liquor, then combine that liquor with the sugar, and THEN roll refine it.

Can you skip pre=refining altogether? absolutely. you'll just end up with lower capacity and higher viscosity

Thanks for the feedback. I will eventually have a mill to produce liquor, so then I'd just need a big mixer to combine it with sugar. Would a large Hobart type stand mixer do the job (~50 lbs at a time) or would I just burn it out? I guess I could always mix by hand and just have one really strong forearm

to mix the liquor and sugar? the hobart will do a great job. be careful to manage your fat levels (you'll want to refine at about 20-23% fat (ish) or else it'll be too 'sloppy' and not refine well). consider putting a jacket on the bowl for temperature control (water jacketed) or heat tape so you can keep the liquor melted (but not burned...)

With the fat content you mention, would it be impossible to refine a 100% (liquor only) chocolate on a 3 roll refiner, or would I just need to decrease the temperature of the paste being fed in to keep viscosity higher?

you want to feed 100% liquor through a roller mill to reduce the particle size? if that's your question, it'd work, but it'll be terribly messy. what you'll find is that, because your liquor is high in fat - the rolls will first 'press out' about 1/2 of the butter, at which point there's sufficient friction for the rolls to grasp the solids and begin to pull them through. the degree of particle size reduction you get at this stage will be different than the degree of PSR you get at the end due to the fat continuing to be expelled.

technically it'd work, but practically it'll be a messy, sloppy, uncontrolled nightmare. i'd avoid.

I don't have any plans for a 100% bar, but I wanted to use that as an extreme example. I typically do 75% bars, but it sounds like even at that fat % it would be a big mess. I know other companies are making 70--75% bars using a 3 roll refiner (using just nibs and sugar)---is the trick to getting that to work just mixing a sugar/liquor mix with the appropriate fat % and refining the remaining nibs in a different machine altogether before combining all in a conche?

best case scenario is to mill your liquor fine enough separately that it doesn't need to go through the refiner, other than to act as a lubricant for your sugars.

you can certainly send coarse liquor + sugar through at 75% (making it 35%+ fat) - it's just gonna be a hairy mess. if that's the only option you have, however, it begins to look pretty attractive!

Will the cocoa butter still be squeezed out if the paste (or the rollers) is at a lower temperature? My goal with a three roll mill is to control particle size (and stay within my budget), and refining on anything else would either lessen that control or exceed my budget. That, and I was hoping to avoid more hairy messes

Yes.

If I had a set up to make a 75% chocolate that allowed me to roll refine a ~50:50 mixture of coarse liquor and sugar, then had a separate machine to refine the rest of the nibs to their final particle size, rheologically speaking, would it be worth it (i.e., would viscosity be noticeably reduced), compared to refining all on the machine capable of handling high fat refining, assuming they are made such that moisture levels in the finished chocolate are the same.