Thursday, February 14, 2013

The Scientist's Valentine

It's Valentine's day, and you haven't planned anything. And — just so we're clear — this is not one of those foolproof last-minute Valentine's Day desserts that will distract your special someone from your failure to produce flowers / dinner reservations / bling on the day scheduled by the greeting card industry. 

But you know what? Anyone can make reservations and buy flowers. But can just anyone waltz into the kitchen and whip up a rich, creamy, decadent chocolate mousse? Can they do it using only chocolate and hot water? 

No, they can't.

Apparently, neither can I.

HervĂ© This can, but that's because he's a culinary badass. He literally wrote the book on molecular gastronomy — the science of cooking. Also, he probably wasn't trying to take pictures with one hand while whisking with the other and sloshing water from his ice bath into the melted chocolate sauce. 

Also also, he probably followed the recipe and used water instead of beer. 

To be fair, a) I did make it with water first, and had the exact same results as far as texture and stability, and b) I used a lovely dark rich oatmeal stout, which is a perfectly reasonable accompaniment to chocolate. And anyway, what says "Valentine's Day" more than chocolate and beer? And possibly despair.

The cream-less, egg-less chocolate mousse is pure molecular gastronomy: food coaxed in an unusual direction through the application of chemistry and physics. In this case, the difficult part is making a mousse with nothing but chocolate and water (or beer), without the cream, eggs, or other ingredients that typically give it its body and texture.*

*Why would you want to skip the eggs and cream anyway? Possible reasons: if you or your special friend is pregnant, you'll want to avoid undercooked eggs; if you're lactose intolerant, you'll want to avoid cream; if you're vegan, you'll want to avoid both; and if you're a foodie, you'll want to do it just so you can throw around words like "tensioactive molecules."

I used my favorite 85% cacao chocolate bar from Trader Joe's, but I'd probably recommend a 70% here. For my first batch, I used water; for the second, I used a dark, creamy oatmeal stout beer — I used Firestone's Velvet Merlin, because it's what was convenient, but any deep stout or porter could do nicely. 

The recipe is simple: melt a half-pound of chocolate in 6 ounces of water, whisk until smooth, then pour it into a bowl set into an ice bath and whip it into a thick, creamy mousse. 

Whisking the chocolate and water creates a smooth emulsion. Whipping incorporates tiny air bubbles, and doing it in an ice bath causes the melted chocolate to crystalize around the bubbles, giving the mousse just enough structure to keep the bubbles from collapsing while staying soft and creamy.

Unfortunately, I whipped my chocolate sauce too long, or possibly cooled it too quickly, and it ended up kind of dry and thick and grainy. 

The book says that if the texture's wrong, you can melt it back down and try again. Add a touch more water if it's not light enough, a touch more chocolate if your chocolate doesn't contain enough fat, and if it's grainy, just don't whisk it as long next time. 

I melted it down and whisked it again, this time skipping the ice bath and just setting the chocolate cool on its own. It came together, started to thicken, got almost perfect… and then the emulsion broke, the cocoa butter from the chocolate separating and rising to the top as oily droplets.

So what was going wrong? Basic issue: fat (cocoa butter, for example) doesn't like to mix with water. Make a salad dressing out of oil and vinegar, and ten seconds after you shake it up, it's separated into layers. Shake it up harder and the oil will forms smaller droplets, which will stay suspended longer, but still eventually join together and separate. 

What you want, whether you're making chocolate mousse or salad dressing, is a stable emulsion: tiny drops of oil suspended in water (or the other way around, depending on your recipe) and held apart so they don't join up into an oil slick. 

(With the right equipment, you can make fat droplets so tiny that surface tension alone is enough to keep them separate, but your stick blender is probably not powerful enough to make this happen, no matter what the infomercial promised.)

It helps to have a stabilizing agent. Something whose molecules have one side that binds to fats while the other holds onto water molecules, holding everything together like the middle sister in a family photo. 

Proteins tend to do well in this role, which is why many emulsified dressings and sauces (and most chocolate mousse recipes) contain eggs, cream, or both. Chocolate contains lecithin, which should work as an emulsifier, but clearly it wasn't enough to hold up against the heat and over-beating. 

Here's the part where I'm supposed to say "And then I simply re-melted the chocolate, scooped out the oily top layer, and then drizzled it slowly back in while whisking, thereby re-emulsifying the oil and producing a delicious, smooth, creamy mousse." 

Or, alternately, "And then I said 'screw it,' re-melted the chocolate, and added a tablespoon of beaten egg (or some cream, or a dash of that soy lecithin extract powder I got from the molecular gastronomy store) and whisked it up et cetera."

I did neither of those things, because at this point I had been having little tastes of the mousse at various stages for over an hour, and determined that even when the texture was just fine, a mousse made from 85% chocolate is a little overbearing. Delicious as a bite or two, but not something you really need to eat a whole dish of.

Also, I was tired of whisking. 

So instead of re-melting my oily, grainy, lumpy chocolate goo, I mixed up a batch of quick dough from a recipe intended for cinnamon rolls. Instead of spreading the rolled-out dough with cinnamon and brown sugar, I used the chocolate goo, then rolled the whole thing up and sliced it into a dozen chocolate-dough spirals. 

Baked in a muffin tin per the cinnamon roll directions, my chocolate rolls were exceptionally delicious. Not quite as stylish and decadent as a chocolate mousse, but then, neither am I.