AskTCL: Is It Possible to Rescue Seized Chocolate?
A ChocolateLife member asked “What happens at the molecular level to make it impossible to temper seized chocolate” I’ve known the what, but never the why. Here’s what I learned.
The TL;DR
Small amounts of water hydrate the sugar and cocoa particles, making them clump and form a rigid network that breaks the fat-based dispersion, so the cocoa butter can’t flow, melt uniformly, or crystallize into the desired Form V structure.
At the atomic/colloidal scale ...
... a small amount of water triggers particle wetting and aggregation, collapsing the fat-continuous suspension. That collapse makes properly melting and crystallizing cocoa butter into the stable Form V phase impossible until either the free-flowing fat phase is restored (by adding sufficient fat) or a water-continuous emulsion (suitable for ganaches, etc., not tempering) is formed.
In More Detail ...
The sugar and finely milled cocoa solids in chocolate are dispersed as solid particles within a continuous phase of cocoa butter; technically, a suspension, not an emulsion.
The sugar and cocoa particles are hydrophilic; cocoa butter is hydrophobic.
When small amounts of water are introduced (to melted chocolate), the sugar and cocoa particles are preferentially wetted, creating microscopic patches of syrup. That wetting glues nearby particles together via capillary bridging, rapidly building larger agglomerates, creating particle networks. These networks trap and exclude much of the fat, converting the low-viscosity chocolate suspension to a thick, grainy paste.
Once that network forms, the system is no longer a fat-continuous dispersion; it’s a partially hydrated particle gel with separated cocoa butter. In practical terms, the uniform flow and shear needed for melting and tempering are lost.
Tempering requires distributing and growing specific cocoa butter crystals (Form V) while melting out the less stable polymorphs. Tempering depends on a mobile fat phase, controlled cooling, and agitation. In seized chocolate, the immobilized solids prevent effective heat transfer and shear, the fat pools are disconnected, and crystal seeding can’t propagate through the mass, so you can’t achieve or maintain the desired Form V microstructure.
Possible Solutions
- Add enough melted cocoa butter to the seized clumps to restore the free-flowing fat phase.
I can offer no guidance on how much cocoa butter might be needed to do this. It will depend on the amount of seized chocolate, particle size, the ratio of non-fat solids to fat in the initial recipe, and other factors.
It may also be more efficient to reconstitute the seized chocolate in a refiner (melanger) rather than just retempering it, which would also probably requiring heating the chocolate to above 115ºF (45ºC) and keeping it there for an extended period of time.
- Add enough water to create a water-continuous emulsion, e.g., a ganache, syrup, or sauce.
I can offer no guidance how much water you add, and in what form (milk, cream, butter, plain water, or a mixture of plain water and another oil, e.g,. olive oil) to use. That depends on the quantities involved and the liquid (and fat content, if any) being used, in addition to other factors.