I can understand why chocolate seizes when it gets wet. - Chocolate is very dry and any available water is bound up by the sugar or lecithin. The fat coated particles glide past each other nicely. Add a little bit of water and the particles stick together.
What I don't understand and haven't been able to find yet is what happens when chocolate gets too hot. - Experience tells me it burns easily as well as gets very lumpy. However, I don't understand the chemistry of it. Is it the cocoa butter or cocoa solids that are burning? Perhaps it's the milk or sugar burning?
Can cocoa butter take high heat? I've read on here about adding cocoa butter to caramel at the end of cooking the caramel. Can cocoa butter take 230+ temp (i'm in the mountains so we don't cook our caramel as hot.) I've been concerned it will burn and taste bad.
We made a batch of caramel with cocoa butter (adding it at 160 & 140 degrees Fahrenheit) but stirring at those lower temps caused the caramel to crystallize.
Does anyone have an article on cocoa butter or chocolate seizing from heat?
imho, you're conflating two distinct phenomena:
when chocolate seizes upon introduction of water, we're observing a largely physical interaction, at least as you described it.
when chocolate is burned, thermal decomposition of cocoa butter, or, more appropriately of the mixture of the three triglyceride fatty acid esters (palmitic, stearic and oleic) + that of the residual free fatty acids present dominates. that thermal decomposition is a chemical phenomenon, that is to say, new molecular entities are created from the parent ones present in the chocolate initially.
you might want to look into what happens rheologically when plant oils decompose. afair (going strictly off very old memory only), they oxidize and cleave into shorter molecules. that will happen especially with the oleic acid and its fatty ester because that molecule contains an unsaturation aka a double bond. those double bonds are prone to oxidation at higher temperatures and that, in turn, leads to the fatty chain cleavage. when the fatty chain gets shorter it stops being fatty. that is to say, as the fat decomposes it loses all the relevant properties we come to associate with those fats.
so, when the chocolate seizes due to overheating/burning, that is likely because an increasingly larger fraction of cocoa butter stops being cocoa butter. that is an irreversible chemical process.
when chocolate seizes from water, that potentially could be reversed (though the chocolate connoisseurs will shoot me for stipulating this) by drying off that excess water or by adding cocoa butter or additional emulsifier like lecithin to take up the extra moisture. incidentally, we manufacture sugar-free and dairy-free, vegan chocolate and any "extra" moisture will definitely seize that version too. so the water doesn't have to be taken up by sucrose or lactose or lecithin. i think some "natural" amount of water is tolerable even without the sugars and emulsifiers.
It's my pleasure. I know the gratification when all the little pieces of the puzzle finally fall together. Even when there are missing pieces, I can still make out the "big picture" and it's a great feeling.
We've come to chocolate from science and with a mission to remove sugar and replace it with natural non-"-ose" sweeteners, so much of what you asked (and more) is something we had to figure out, and figure out "backwards". By "backwards", I mean figuring out what in the "sciency" stuff applies to the wide world of chocolate and how. I think that's called "learning the hard way". :)
But enough memory lane stuff. I googled your question re smoke points and came up with 280F for cocoa butter on "http://www.kingarthurflour.com/recipe/fats.html (hit the melting point tab in the table midway through the page). I suspect that number is highly variable based on what I've read about how cocoa butter is pressed and refined. There is a paper from one of the large cocoa processors and sellers floating about where they describe what effect the removal of residual free fatty acids has on properties of the resulting cocoa butter. I only skimmed through it, but it was fascinating. They never (afair) talk about the smoke points, but lots of other relevant info is abundant. If you want, I can try to dig it up and link you.
Back to the smoking point: I suspect the relative ratios of the three fatty acid esters vary in the cocoa butters from around the glove, and so do the amounts of the free acids. That (amongst other things) is what gives each material its distinct regional flavor signature. The post processing and pressing temps and procedures themselves would result in different compositions of cocoa butter with different amount of impurities. In the booze and chemical industry the fraction interesting to us is often referred to as "low boilers". Those low boilers provide the aroma, flavor, etc. because of their lower vapor pressure. That and other fractions could be responsible for lowering the smoke point too: while the 280F bar is still there, those entities with lower thermal stability would start decomposing, smelling and smoking and masking the "true" cocoa butter flavor and decomposition.
If you look at the link, you will see that clarifying "regular" butter (i think that's called "ghee") buys you 25F of stability (375F from 350F). That is the process of removing of those "suspect" impurities/low boilers.
I hope this makes some sense. I really want to continue this thread about seizing chocolate from the technical point of view. Lord knows I am responsible for the destruction of a ton of chocolate that I seized e while figuring a lot of things that are "obvious" to regular chocolatiers.
Thanks for starting this thread. I want to talk about what folks know about reversing the physical seizure. If anyone has "saved" chocolate ruined by water, I'd love to discuss that.
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