My column in today's New York Times Dining section is about a batter for fried fish developed at The Fat Duck, Heston Blumenthal's restaurant west of London. I first enjoyed the very crunchy crust it makes last spring, when Christopher Young, the restaurant's research manager--yes, they do enough research at The Fat Duck that it needs managing!--demonstrated it at the Greystone campus of the Culinary Institute of America. The key ingredient is alcohol.
The story with the fish batter was that we had developed a really fantastic batter recipe using special starches from National Starch. By using these, along with the siphon to create a very irregular foam structure (an idea that based on the work of Julian Vincent at Bath University and the mechanics of brittle fracture) we created a really outstanding batter that would cook fast enough so that the fish wasn’t over cooked, but stay crisp for a good 20+ minutes. The only downside to this was that no one could recreate this batter at home.
We mostly dealt with this “pickle” by waiting for divine inspiration. That occurred one afternoon at my house when I was reducing alcohol for a sauce and while I had my back turned it boiled away to nothing. I was reminded that alcohol takes far less energy to evaporate than water. I thought it might be possible to reduce the amount of water in the batter by replacing it with alcohol and creating a batter that would cook faster. The added bonus was that alcohol destabilizes the foam, which creates a more inhomogenous structure, which makes the batter crisper!
There was a bit of trial and error, because you do need some gluten or the batter just “blows” off the fish. It seems that a final alcohol content of around 20% seems about right.
Inspiration favors the prepared mind!
For the other big advantage that alcohol brings to a batter, see my column. The Times also gives an adaptation of the Fat Duck's recipe for siphonless cooks.