Cookie Dough and Vacuum Cleaners

A lot of molecular gastronomy techniques are hard to implement at home, simply through lack of equipment. The perfect steak is meant to be cooked in a sous vide at 50-65°C, before finishing off with a blowtorch, for example. Xanthan gum and nitrous oxide are blasted through sponge cake mixture to give it the perfect texture. But when I saw a recipe for vacuum sealed cookie dough from The Kitchen as Laboratory, I thought the equipment needed could be improvised at home in a way that it couldn’t be for other techniques.

You might have seen in cookie recipes instruction to leave the dough in the fridge for a while, or even overnight. The idea is that the moisture in the cookie moves around the dough evenly, meaning that you get a moist, evenly baked cookie. The heat spreads around the cookie evenly, giving a nice even texture as well. Cookies which don’t have an even distribution of moisture can go crispy around the edges, and end up crumbly, rather than nicely chewy and soft.

To speed up this process of getting the moisture around the cookie dough, a technique called hydration is used. By subjecting the cookie dough to a low pressure environment, the moisture spreads through the cookie by capillary forces, to create an even distribution of moisture in the dough. This is done by putting the dough in a bag, the bag inside a vacuum chamber, creating a vacuum inside both the chamber and the bag, and then slowly letting the air back into the chamber, which gives the desired drop in pressure.

Cookie dough nested in a vacuum bag

Now, I don’t have a vacuum chamber, but what I did have was some vacuum bags (similar to these ones) which we use to store out-of-season clothes and duvets. By sealing the bags, putting a vacuum cleaner in the entrance, turning it on and then pulling the vacuum cleaner out right when all the air has come out, you can take all of the air out of the bag and keep it sealed up. Hopefully, given the principles were the same, I’d see the same kind of difference in results.

So, scientist as I am, I made a batch of dough and divided it in two, one to serve as the control. The control I would just bake with no resting time, and the other batch would be hydrated. I put the other batch into two sandwich bags, which were put into a vacuum bag and sealed with a vacuum cleaner. Then the air was gradually let back in, to create the all important low pressure environment. The cookies were then baked for the same amount of time, allowed to cool, and plated up.

Hydrated dough (bottom left) vs. Regular dough (top right)

Fortunately, the results were pretty clear. The control batch were crispy around the edges, and were much more crumbly and mealy than I would have liked. The hydrated ones were smooth, moist- consistently so around the edges. They also cooked a lot more evenly- spreading their shape out better. And just to make sure I’m wasn’t being biased with the results, the cookies were tasted by my local cookie enthusiast. She was pretty impressed with how the hydrated ones turned out, but perhaps more impressed that I had finally started to use the vacuum cleaner.

So why not hydrate the dough every time? Given that the extra step in hydrating the dough really wasn’t difficult, taking 5 minutes at most it is hardly extra effort, but had great results. However, I think the main success for me, though, is a molecular gastronomy technique that works well in the domestic kitchen. Cookie anyone?

Top and underside of the two cookies. The regular dough cookie is on the left, the hydrated one on the right.


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