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Post by bmikiten on Nov 24, 2016 9:28:13 GMT -5
I keep hearing about the release of volatile compounds and changes in acidity as chocolate is processed (conch/melanger stage) so I thought I'd test the changes in pH. I used a datalogger and found that after 24 hours there was little to no change in pH. (.22 difference). Are there other indicators that can be measured? It clearly tastes different even after 12 hours.
Brian
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Post by Sebastian on Nov 25, 2016 13:34:27 GMT -5
It's always hard to assess how much scientific understanding someone has on a board, so this may all be information you already know.
pH is a mathematical representation of the concentration of the negative ions in water. Since chocolate is a fat based system (there should be less than, what, 2% total moisture in your chocolate), your pH probe is going to have a beast of a time finding water with which to take a reading. Have you solubilized your chocolate to the extent you can to take a reading?
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Post by bmikiten on Nov 27, 2016 0:22:16 GMT -5
It's always hard to assess how much scientific understanding someone has on a board, so this may all be information you already know. pH is a mathematical representation of the concentration of the negative ions in water. Since chocolate is a fat based system (there should be less than, what, 2% total moisture in your chocolate), your pH probe is going to have a beast of a time finding water with which to take a reading. Have you solubilized your chocolate to the extent you can to take a reading? I'm an engineer and not a chemist but that explains the lack of change. Would detergent do it without making any major changes to the baseline pH? Any suggestions would be helpful. Brian
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Post by Sebastian on Nov 27, 2016 7:17:53 GMT -5
I'd ask what it was you were trying to accomplish? IF you've got a stable fermentation source (any acidity is coming from your fermentation), AND you understand your acidity (there's non-volatile and volatile acids that can be generated during fermentation), then you might consider looking at an atmospheric probe that's sensitive enough to measure the concentration of acetic acid released during conching. However, for most people, they are not able to control the fermentation protocols sufficiently to do this, and as a result, the amount of variation in their bean sourcing is incredibly high - one batch may have volatile acids developed, the next organic, and so on - which would make investing in pH monitoring equipment a frustrating experience in control (or lack thereof), as the supply chain isn't sufficiently well understood to affect the type of control one might be looking for.
Alternatively, you could add small amount of a base ingredient (pH > 7) to your conche and try to neutralize the acidity (NOTE: do NOT try adding highly alkaline materials such as sodium hydroxide, for example, as you'll likely just end up burning a hole in your throat. be warned). There is some indication that adding, say, a sodium bicarbonate (baking soda), at lower fat conching cycles can neutralize some of the organic acids.
Again, your approach entirely depends on what it is you're looking to do. For most folks here, i'd focus on letting the flavor be your guide to informing you when you're 'done'.
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Post by bmikiten on Nov 28, 2016 8:30:49 GMT -5
Thanks for the reply. I'm assuming that the pH changes and the overall volatiles (acetic acid as an example) will reduce over time with grinding and conching. I was hoping to find a way to measure what I currently smell and taste in order to determine that the chocolate has finished going through this process. I've noticed that (using the acetic acid odor as an indicator) some beans lose this odor in 24 hours and some in over 48. The goal was to find an indicator that would identify the point where the line flattened and (past particle size) the chemical processes were essentially complete.
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Post by Sebastian on Nov 30, 2016 0:51:51 GMT -5
That's actually a really big question. W/o knowing the details of your setup, i'm going to assume that you have very little control over your supply chain, and don't have hundreds of thousands of dollars to spend on analytical equipment. If that's the case, i'd continue to let tasting be your guide
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Post by bmikiten on Dec 2, 2016 0:04:06 GMT -5
Doesn't it make sense to be able to monitor the delta values from start to finish of the conching portion of the process? Bean supply, etc shouldn't matter.
Brian
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Post by lilypa on Dec 6, 2016 18:16:53 GMT -5
Could you take a small sample of chocolate out of your conche and mix it with distilled or DI water then to get a pH reading? Would you have to let the sample sit in the water for awhile for the pH to stabilize? Perhaps a manual reading every so often could give you a sense of when you might be asymptoting/flat-lining?
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Post by Sebastian on Dec 7, 2016 6:54:01 GMT -5
You could try (and people have). You'll want to add a surfactant, heat, and lots of agitation. One of the challenges you'll face is that cocoa butter is a great encapsulator, and will encapsulate the organic material, thereby preventing their disassocation in water some of the time, meaning you're results will be difficult to repeat, and it doesn't capture volatile materials. One very large manufacturer uses atmospheric acetic probes for this reason; i'm not aware of any who use pH in the mass itself as a control mechanism, for multiple reasons.
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