Grinding Cocoa Solids Into Powder

Mark Allan
@mark-allan
06/21/14 11:32:14AM
47 posts

I might have a rare problem in that I extract my own cocoa butter using a screw press. The machine serves the purpose of making chocolate. The problem I am left with is doing something with the cocoa solids it removes.

The solids crumble into flakes, which I can grind down a bit using the wet grinder. I just add about two cups at a time to the grinder and run it about 20 minutes. At that point it is fine enough to bake with or use in making chocolate syrup, but not fine enough to mix into liquids, or in this particular case, ice cream.

A local dairy would like to give me the business of producing cocoa powder, but it must be fine enough to dissolve in their ice cream mix. According to the manager, the cocoa I produce is too coarse and shows up grainy in the ice cream. I am not sure what particle size you would find in say, Hershey's, but apparently I am not there.

Does anyone know of any economical solution for this? We have a Kitchenaid stand mixer and I've been looking at the grain mill which makes flour from grains, but I don't know if that would grind it fine enough or not. If not that mill, would any other commercially available mill work?

Thanks,

Mark C


updated by @mark-allan: 04/09/15 08:12:14PM
Sebastian
@sebastian
06/22/14 07:16:48AM
754 posts

your cocoa powder will never dissolve in ice cream - what you need to do is get a sufficiently small particle size that you can't see the individual pieces. commercial cocoa powders are hammer milled down to a very fine particle size (< 8 um). i'm not sure what attachments are available for a kitchen aid, but i'd be surprised if there was an off the shelf solution via that route (i've been surprised before though!). perhaps look for an old sugar hammer mill - i don't think they're very expensive..

Mark Allan
@mark-allan
06/23/14 02:43:29PM
47 posts

Thanks again, Sebastian

Yes, though I could never get a tech spec on the grind mesh range of a Kitchenaid grain mill, I realized it probably was not sufficient to grinding 200 mesh as looks like the max size for cocoa powder. Now I am wondering if the espresso setting on a higher end coffee grinder would work well enough, though I have my doubts.

I have an inquiry for this machineas to the mesh range, but don't have high hopes. I did a search for 'sugar hammer mill for sale' but have not found much yet.

Thanks,

Mark C

Sebastian
@sebastian
06/23/14 09:29:13PM
754 posts

just for giggles, i did a quick ebay search for hammer mills, and a few smaller pieces of gear did show up - caveat: i've never directly used any of the pilot pieces of equipment that are presently listed, so i can't speak to them directly, but there were a few there for less than $500 - i've no idea of your budget, but it could be that it's inexpensive enough to enable a 'try it and see what happens' scenario

Mark Allan
@mark-allan
06/23/14 10:01:50PM
47 posts

My budget is painfully low as I've yet to make a decent chocolate and don't want to get in deep until I prove that I can turn out something edible. I can make confections that are good, but a plain bar, either dark or milk, is too bitter.

This weekend I reset my process to Chocolate Alchemy's method of using a Champion juicer to help filter out more of the shell. Will see how that goes. I'm not sure how this process could be made faster, as it's way too inefficient to ever think of going commercial with it. I am thinking I will try cracking the beans before putting them in the forced air roaster. That way more of the shell should blow off in the 15 minute roast plus 10 minute cool down. The fan removes loose shells.

I'm still hoping to make a breakthrough and experimenting with different aspects, but the beans I buy from the local market, as described in a different thread, are not fermented sufficiently. I'm still waiting for a neighbor to come up with properly fermented beans but trying to improve on the market beans in the meantime.

Larry2
@larry2
06/25/14 11:46:41AM
110 posts

I've been curious about grinding the cocoa flakes.

I reached out toone of thesellers of the machines on ebay running around $500. It looks like that machine will not get as fine as the commercial cocoa powders. They replied that with a 400 mesh screen, you could get down to around 0.037mm or 37000um. Here is our conversation string.

I wonder if you could make a500/600 mesh screen to fit.... ???

hello sir
if you want to get 15 nm, i think our machine can not get your need, cause we just can get 400 mesh, it is around 0.037mm
chelsea

- no.1-shops




Subject:NEW Automatic continuous Hammer Mill Herb Grinder,hammer grinder,pulverizer #150980503835
Sent Date: Jun-24-14 09:05:05 PDT

Dear no.1-shops,
I would like to grind cocoa powder. - The cocoa beans will be roasted and have most of the cocoa butter extracted. My extruder gives me flakes of cocoa solids.
The problem we've had is getting the powder fine enough that it will work well in ice cream. - our current coarsness of powder makes the cocoa appear grainy when frozen.
Thank you,



NEW Automatic continuous Hammer Mill Herb Grinder,hammer grinder,pulverizer #150980503835
Sent Date: Jun-23-14 18:16:54 PDT


what do you want to grind?
chelsea

- no.1-shops




To: no.1-shops
Hammer Mill Herb Grinder,hammer grinder,pulverizer #150980503835
Sent Date: Jun-23-14 13:13:04 PDT

Dear no.1-shops,
How fine will the grind go? - I'm looking to get down to 15 nm.


Mark Allan
@mark-allan
06/25/14 07:23:47PM
47 posts

Man there's got to be a way short of $10K to pulverise cocoa powder. I thought I read that cocoa powder can be as large as 200 mesh.

Sebastian
@sebastian
06/26/14 06:21:49AM
754 posts

Larry - it may be a typo, but you've got 15 NANOMETERS as your particle size target, not 15 MICROMETERS. huge, huge, huge difference...0.037mm = 37 um (not 37,000 um)

Mark - sure, it can be large, but then you have large, visible particles in your finished application. For cocoa powder, finer is almost always better. Historically the low grade asian cocoa producers were characterized by their large particle size - that's changing, but generally speaking cocoa powders users want a fine powder.

Mark Allan
@mark-allan
06/26/14 07:54:47AM
47 posts

Hi Sebastian,

OK, what mesh size should be required? 500, as Larry was requesting? Or is the 400 small enough?

Thanks

Larry2
@larry2
06/26/14 09:31:46AM
110 posts

Oh boy, what a novice mistake. Thank you for catching it! :)

This site has a useful chart on converting mesh size to particle size

http://delloyd.50megs.com/moreinfo/mesh.html

this site will send a 3"x3" sample of their 500 mesh screen. It may be large enough to work some magic. :)http://www.twpinc.com/wire-mesh/TWPCAT_SS_Fine/p_500X500T0010W40T

Several of the charts referenced that a 400 mesh screen is as fine as can be made. Perhaps it would simply be impractical due to clogging and so forth.

Could you just run the powder through again after working it down to a 400 mesh screen? In theory the cocoa powder would continue to refine as it goes through the mill. I think it would just go through faster because the particles are already small enough to fit through the mesh.

This would probably result in an inconsistent size, but it may work...???

Another question I haven't thought of sorting out, is how small does the powder need to get to not be grainy in ice cream? Mark, do you know how fine your cocoa powder is right now? Is it as fine as a very fine sand (200 microns) or as fine as Portland cement (74 microns)

If the current particle size is large enough, then getting down to 37 microns may be a large enough improvement to work with.

Has anyone requested a quote from on the Pallman mills? http://www.pallmannindustries.com/chocolate_products_-_pulverizing....

I haven't bothered them, but I wonder how much one of their mills would cost. I couldn't find anything reference a finished particle size on their site, but if they are selling it as a solution to the chocolate industry, it must be pretty good.

Sebastian
@sebastian
06/26/14 09:06:53PM
754 posts

Typical high quality cocoa powders average 8um. there's a distribution, of course - some will be larger, some will be smaller, but it gives you a feel for it. how big is 'too big' for ice cream? that's a very individual question with no clear answer, depends on who's looking at it. finer is always better. 200 um will be too large, as i suspect 74 um will be as well.

what you may be able to do is mill it, use a very fine screen to sieve it, and whatever it retains (i.e. the 'overs') have those remilled until they pass your sieve. it'll be a time consuming process, i wager, but should be effective.

Send him some of your unmilled material and ask if he'd run it for you to see what it yields?

Mark Allan
@mark-allan
06/27/14 09:23:03AM
47 posts

Hi Sebastian,

I did some follow up on the hammer mills you found on eBay for under $500. The finest mesh they have is 250, 57um. That is probably finer than I am making it with my stone grinder, but from what you said below, probably not fine enough to mix into ice cream?

We're going to try and figure out what size Hershey's Cocoa is with a microscope.

Thanks,

Mark C.

Sebastian
@sebastian
06/27/14 10:54:22AM
754 posts

The answer is above, i'm very, very, very familiar with it 8-)

I'd explore asking the vendor if he'd mill some powder if you'd sent it to him, ask him to return it to you milled, and then make some ice cream out of it (i'd not consume it yet) for visual inspection.

I wonder if it's as simple as having someone else make a mesh to fit their equipment?

Mark Allan
@mark-allan
06/27/14 11:06:15AM
47 posts

Making a mesh, I wonder too if that's a possibility. We have machinists here, but not sure if they could do something to that level of detail. Larry showed a link above to a company that makes mesh.

As far as doing the sampling, there's a logistic problem. We live in Honduras and the vendor is in China. Getting things in and out of Honduras to/from the USA is difficult enough. I'd have no clue how to do that with China.

If we can get our microscope back from a friend, I will try and measure Hershey's, and then see if Hershey's works for the dairy.

The cocoa we crush with the grinder works well for baking recipes, we just don't know a lot of people in our area who bake very often. The dairy, on the other hand, buys 50 lbs of cocoa, imported from Spain, to make their ice cream.

I watched the video included on those eBay machines, showing how they operate. I am wondering if it would work to add some mesh behind or in front of the screens they provide. Such as, buy some 400 mesh and place it in front of the 250 mesh screen.

http://www.twpinc.com/wire-mesh/TWPCAT_12/p_400X400T0012W48T

Sebastian
@sebastian
06/27/14 12:23:26PM
754 posts

Possibly. Mind the tolerances so that your hammers don't end up turning your screen into screen dust.

Mark Allan
@mark-allan
06/27/14 12:55:43PM
47 posts

Thanks. After I made that last reply I was weighing the pros and cons of putting the 400 screen in front of the 250, and vice versa. Still, even as low as $500 sounds for this craft, I am going to wait until I can produce a chocolate bar worth continuing on with. I am still hoping it's the under fermented bean. I tried being really careful about getting no shell/husk in the chocolate, and grinding for a couple days, but I still did not notice a drop in bitterness. Our neighbor is on the lookout for properly fermented beans among the other cacao farmers he knows.

Mark Allan
@mark-allan
04/09/15 08:31:07PM
47 posts

It's been awhile since this was updated. I was able to find a quality supplier of cocoa, one with properly fermented beans. I have been selling 70% dark bars, amont many other chocolate covered things, for about eight months now. I also bought a cocoa pulverizer that hits about 24000 RPM's. Machine costs about $200. It does a good job of making the powder fine, but it lacks a screen so some of the particles don't get as fine as I would like them. The local dairy is going to try the powder tomorrow.

I've also cracked the recipe/code of a very popular, fairly expensive, brownie mix maker. That is how I've been getting rid of the coarser cocoa powder so far and the brownie mix is selling well.

Larry2
@larry2
04/10/15 12:35:01AM
110 posts

That is really great to hear! Way to go on selling & getting things rolling.

Balu Bala
@balu-bala
04/20/15 12:58:25AM
2 posts

I think 500 to 500 mesh powder should be fine with icecream.

As far as the hammer mill, find the one that has the largest screen as possible.  It is critical to mix with lots of air during grinding process to keep the powder form getting hot and melt inside the mill.  Perhaps mix the feed with dryice could keep it from melting during grinding.

Mark Allan
@mark-allan
05/13/15 11:00:02PM
47 posts

OK, I have small, 200g spice grinder that turns at 28000 RPM. I was hoping it would work well enough for cocoa powder, but the problem is that some grains are larger, others are small. There is no mesh/screen on it. You just set the timer, it starts spinning and you take what you get, not good enough. The result is still too grainy for ice cream.

I am going to try a low tech solution, which is common in this country. Will rubber band strap a piece of 400 mesh screen where the lid of this machine would go, with a good rubber band, and put a plastic bag over that. Turn it on, tilt it back and forth and see what comes out. The screen comes next week. Hoping for a breakthrough, a cheap one.

400 mesh screen is sold on eBay in 12"x12" pieces, for $9, free shipping. If this works I might consider writing a book on single source chocolate, for under $1000.  (not really)

We can already make good chocolate, single source, but we have leftover cocoa powder that is not fine enough.

Sebastian
@sebastian
05/14/15 06:12:19AM
754 posts

I suspect that'll work, but it'll be slow going.  Only potential watch out i'd see is that if your cocoa press cake isn't low enough in cocoa butter, said cocoa butter may heat up during grinding and turn to a paste in your spice grinder, at which point grinding effectively stops.  If you see that happening, you'll just need to grind in shorter bursts (or add a small amount of dry ice to grinding), but i do suspect it'll work.


updated by @sebastian: 09/08/15 04:00:13PM
Mark Allan
@mark-allan
05/14/15 10:05:08AM
47 posts

I've come to realize that's why a lot of people caution me, even vendors of hammer mills, on grinding cocoa. What our screw press churns out is pretty dry and I have run it in our grinder several times. The grinder does get too hot to touch, but the powder always comes out as powder, grainy, but powdery nonetheless, not pasty.

Otherwise, thanks for the vote of confidence. I think it will probably be slow as well, but we are really small scale right now anyway. For the brownie mixes we make, we do not need a 400 mesh powder. For mixing into ice cream, I think a 400 mesh powder will suffice based on what I've seen with earlier experiments. The ice cream is brown, but it has grains. We just have to keep the larger grains out.

Maybe someday we'll get a hammer mill, but I am hoping the investment will make obvious sense by then.

Sebastian
@sebastian
05/14/15 02:46:23PM
754 posts

looking forward to hearing how it goes!

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