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Post by Fat Rabbit Coffee on Mar 20, 2023 14:13:19 GMT -5
I've never gotten air bubbles when molding chocolate before but got quite a few this time around. I racked (wracked?) the molds and got bubbles on the surface (back side) to pop but there were holes on the face when I took the chocolates out of the molds. There also seemed to be more bubbles in general when I poured the chocolate. What are the various reasons this can happen?
And a 'snap' question. I do have decent snap but it's not as snappy as I think it could be. Shelf stable - not melting at all - but wondering if I had brought the temp up just one or two degrees more, would that have helped make the snappier? I'm using 70% cacao, 5% cocoa butter, and 25% straight up refined white sugar.
Thanks for any thoughts!
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Post by Ben on Mar 21, 2023 10:29:32 GMT -5
After the chocolate comes out of the grinder, it will have a lot of air in it. Stirring it well while tempering, while being careful not to incorporate more air can help to get the air out. Also, really vibrating the chocolate in the molds helps a lot. It could also be that your chocolate is a little thicker this time. This could cause it to be more difficult to get the air bubbles out and for the chocolate to flow fully into the molds, leaving bubbles on the face of your bars. Thickness could be due to over-refining, more moisture, and over-tempering. There's probably more reasons that those, but those are what come to mind right now. Regarding the snap question, it may be that your chocolate is not fully tempered. Can you give us more info on your tempering process? It could be that bringing up the temperature would have a negative effect on the snap. My guess is that you may need to hold and stir the chocolate at your final temperature longer to allow more crystals to form and propagate through the chocolate. On the other hand, taking the chocolate to a warmer temperature could make it flow better and allow the air bubbles to release more easily. It may be that you could warm the chocolate and hold it there longer and achieve both goals. During the tempering process, crystals are either forming or melting all the time. The goal is to get enough crystallization that the chocolate sets properly when cooled, but not so much that it gets too thick to work with. Knowing that, you can adjust your process to get the results you want. Once you have reached your final temperature, test a bit of it and if it doesn't set up properly in a couple minutes (solid, good snap, no swirls, no melty-edges) then you can either hold it at that temp for a few more minutes and test again, cool it down a bit, or take other measures to get the chocolate in temper. If it sets up well, but has gotten too thick to work with (or even just thicker than you'd like) you can bump up the temperature or just hit it with a heat gun a bit to melt out some of the crystals. Note that completely un-tempered chocolate won't melt at room temperature, so chocolate not melting is not a sign of it being in temper or being shelf-stable.
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Post by Fat Rabbit Coffee on Mar 21, 2023 12:08:50 GMT -5
Great reply, thank you.
I tempered by taking the chocolate right out of the melanger (about 14 hrs in the melanger) into a bowl. I believe the temp was around 109F. I let that cool down to about 81F. I put this bowl into a larger pan with a shallow amount of water in it and put that on the stove and gradually heated it until the chocolate temp read about 86F. I turned off the heat so it wouldn't run away on me until I got around 87-89F and I was stirring the entire time.
I used a large syringe to "inject" the molds. Might using a syringe introduce air bubbles? I've read a lot about people using them and it's really convenient but after this batch I was wondering if spooning the chocolate in would have been better.
What's your suggestion for how to hold the chocolate at a set temperature? If my target temp is 88F is there a rule of thumb about how hot the water bath should be?
Another weird thing is using the exact same molds (same design, different trays), some of the bars came out looking nice and clean on the face and some sort of crumbled away leaving a partially rough surface.
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Post by Ben on Mar 21, 2023 12:52:41 GMT -5
I think 88F is a little on the cool side--at least it's much cooler than I like to mold. I generally mold between 91-92F.
When cooling are you just letting it sit until it reaches that temperature or are you actively cooling it using an ice bath or similar? If just letting it sit, check out Brad's two-bowl method video. It's linked in several threads on this forum and should come up in a search. It'll save you some time and may help to generate more crystallization. Also, are you stirring while it cools?
I've used syringes for many years and haven't noticed them adding air, assuming I don't draw any air into the syringe itself, of course.
To hold the chocolate, just keep your eye on the temp, and when it starts to cool, pop it back on the double boiler for a short time or hit it with a heat gun. I don't know of any rule of thumb for how hot the water in the double boiler should be, but I do know that it (counter-intuitively) should not be boiling.
That some bars stuck in the molds and crumbled away suggests that the chocolate wasn't properly tempered. Do you test the temper before molding?
Also, what size batch are you grinding? 14 hours seems pretty short to get a smooth texture.
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Post by Fat Rabbit Coffee on Mar 21, 2023 15:43:35 GMT -5
When I first got into all this I started with the two bath/bowl method but then thought, "Why am I doing all this back and forth between two different temperature bowls when I can just use a single bowl for warming the chocolate back up?" I ran this by John Nanci and he said at my batch size (1100g roasted so ~900g in the melanger) that should be fine.
In the past, I have put the bowl in the fridge to speed up cooling a bit but I was multitasking this last time around so just let the bowl sit out for a while to let it cool on its own. By the time it got down to ~84F, I actively stirred it and lifted it with my spatula to expose it to more air and look for clumping.
Heat gun is an interesting idea. I'll have to have that on hand next time.
I did not test the temper before molding. I think that's something I need to start working into the process.
How long would you recommend melanging for? (900g ingredients in a Spectra 11) It's for personal consumption at the moment and despite the issues with this last batch, it's still delicious, but the goal is to churn it out as professionally as I can here at home.
You've given me some good tips for next time. Thanks for all that!
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Post by Ben on Mar 22, 2023 12:27:12 GMT -5
I prefer active cooling to just letting it sit. I seem to remember reading something years ago about it being better for crystal formation, but that may not actually be the case. I'd highly recommend testing your temper with every batch. You just can't rely on the chocolate crystallizing correctly just because it went through the various temperatures. I use 3 commercial tempering machines and I still test every time. If you're getting the texture you want and are happy with the taste, there's no real need to adjust your grinding time. That being said, I'd recommend experimenting with a 24 hour grind and see what you think. My guess is that it'll be smoother and the added time should help to drive off more moisture, which should result in a less viscous chocolate.
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Post by Fat Rabbit Coffee on May 12, 2023 0:23:21 GMT -5
This is a followup to my initial question about air bubbles. See the attached images of my custom mold and the resulting bar. The bar itself is nearly perfect aside from several holes (air bubbles?) in the lettering and one on the tip of the nose and foot. Thoughts as to why this is happening and how to fix it? Improving from my previous tempering method, I tried silk this time and the process was a lot easier with better results. I haven't attached images of the other molds I poured (hearts, cubes, basic bars) but none of them had holes in them. Attachments:
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Post by mark on May 12, 2023 6:29:09 GMT -5
That’s a nice custom mold you’ve made there, well done. That text is quite fine, so I think you’ll want to aggressively vibrate those bars as soon as you’ve deposited the chocolate into them. I’m not sure what the viscosity of your chocolate is like. If you’re making two ingredient bars around to 70% mark the viscosity can be quite low depending on the beans you’re using. One of our origins makes a 70% two ingredient bar that is really thick. I have to preheat the molds and deposit into the moods while they’re on the vibrating table to have any hope of the chocolate spreading out across the entire area before it sets.
You may be having a similar issue here. That little bit of air on that text won’t rise through the low viscosity chocolate unless you band the mild down hard on your bench top or vibrate it hard for a few minutes. If your custom moles are transparent you will be able to see the air bubbles in that text from the bottom so you’ll know if you’re banging or vibrating has done the job.
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Post by Fat Rabbit Coffee on May 12, 2023 16:27:20 GMT -5
Thanks Mark. I can take credit for the design but hired an outside company to make the mold. I figured I'd end up spending at least as much trying to do it myself, factoring in mistakes, so paid a professional.
This chocolate was 70% cocoa, 5% cocoa butter, 25% granulated white sugar.
I did of course rack the molds but perhaps not hard enough. Looking from underneath is a good idea - I'll try that next time to see if I can see anything.
If I want to lower the viscosity a bit to help it along and stick as close to 75%, what do you recommend? Go down to 70% (does less cocoa, more sugar make it less viscous?)? 65% cocoa and 10% cocoa butter?
Maybe I'll try heat gunning the mold just a bit as well.
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Post by Ben on May 13, 2023 11:01:28 GMT -5
If you're not already using a vibrating table, I'd recommend getting one. I find them to be better at getting out air bubbles that banging the molds on the table by hand. This is due to the type of non-Newtonian fluid that melted chocolate is. Basically, vibration temporarily lowers the viscosity, allowing the chocolate to settle into the mold and release air bubbles.
To actually lower the viscosity of the chocolate, increase the percentage of the chocolate that is cocoa butter. Assuming that your nibs are roughly 50% cocoa butter*, you can figure out the solid/fat ratio pretty easily:
70% cacao, 5% cocoa butter, 25% sugar = approx 40% fat, 60% solids 65% cacao, 5% cocoa butter, 30% sugar = approx 37.5% fat, 62.5% solids 65% cacao, 10% cocoa butter, 25% sugar = approx 42.5% fat, 57.5% solids
So, all else being the same, the final ratio have the lowest viscosity. It may not have the taste you want, though.
On a side note, keep in mind that there are other ways to lower the viscosity, or to work with higher viscosity. Moisture in chocolate makes it thicker, so any way that you can reduce moisture will help to lower the viscosity. Adjusting the roast or adding heat during refining/conching can help, and I know of several chocolate makers who put their roasted nibs in a proofing cabinet overnight. Additionally, real conching helps a lot, but that requires an additional machine if you're using a stone grinder.
* They're generally somewhere between 50%-55%, although I'm sure there are some that go higher and lower. I generally just use 50% when thinking about this sort of thing.
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Post by Thomas on May 14, 2023 13:20:08 GMT -5
Lecithin will lower the viscosity as well and does not alter the taste. But this is assuming you don't mind adding lecithin. I didn't notice this mentioned in any of the post but I may have missed it.
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Post by Fat Rabbit Coffee on May 15, 2023 13:02:57 GMT -5
I think I mind adding lecithin. I've read about it and it may be a silly notion to not include a natural product even if it helps the outcome just because it's not as "pure" and it's "another added ingredient" but definitely something to keep in mind if my success with other options doesn't pan out. Thanks for the suggestion.
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