Kitchens are great for science, involving a mix of chemistry, physics, biology, a bit of mathematics, perhaps medicine if you’re doing it wrong…
If you’re interested in that sort of thing, the best resource is Harold McGee’s classic book On Food and Cooking: The Science and Lore of the Kitchen (that link is to his website, curiouscook.com).
And it’s Harold McGee who provided the solution to a problem I recently encountered at a chocolate party. Chocolate fondue—where you dip fruit, marshmallows and other tasties into melted chocolate—is prone to seizing, which is when it turns into a solid lump that’s no longer dippable.
This generally occurs when moisture is added to the melted chocolate. Chocolate consists of a fatty substance called cocoa butter, with little particles of cocoa solids suspended in it. These solids contain starches, proteins and other chemicals that give it its flavour. Because we like to sweeten it, there are usually also sugar crystals and, if it’s milk chocolate, particles of milk protein.
What it doesn’t contain is water. When you add anything wet, such as fruit that’s just been washed, or as we did, a small amount of cream, the sugar crystals form a syrup that sticks together all the particles of protein and starch to form a pasty lump.
If this happens to your fondue, don’t throw it away! You can never un-wet it, but you can make it suitable for dipping again by adding more cream. For starters, the water in the cream will fully dissolve the sugar into a liquid syrup. But it also contains natural emulsifiers, so if you mix it in well it will turn the cocoa butter into a nice, creamy emulsion.
And there’s a name for an emulsion of chocolate and cream: we call it a ganache.
To see this rescue operation in action, watch the following exclusive Lost In Science video:
How do you stop getting into this mess in future? Well, apart from being very careful not to get moisture near your melted chocolate, you can embrace the ganache, and heat the cream first then add chocolate to it.