Lifting the lid on CHOW.com's Test Kitchen to reveal the process behind the recipes.
Real astronaut ice cream is a freeze-dried mixture of fat, milk solids, and sugar—NASA loaded some onto Apollo 7 in 1968, but since then, it's mostly been a crisp-textured snack for kids in science museums. In an upcoming CHOW video series, we'll explore how to re-create the process at home. To develop the recipe for said video series, we had to figure out a way to approximate the taste and texture of astronaut ice cream without actually freeze-drying it. (Freeze-drying requires complicated, expensive equipment, such as a powerful vacuum chamber.)
Our first idea was to make a version of dehydrated milk foam, a molecular gastronomy–style preparation that's sometimes found crumbled around the edges of high-end restaurant dishes these days. It tastes a lot like astronaut ice cream, and we wanted to see if we could get it even closer.
We found a recipe in Daniel Humm and Will Guidara’s Eleven Madison Park cookbook that called for liquid glucose. We were able to source some at a cake supply store south of San Francisco. (Apparently it's most commonly used to make fondant for wedding cakes.) The recipe had us heat the glucose with whole milk on the stove until nearly boiling, then create foam using an immersion blender. We weren't able to get much foam this way, but then somebody suggested we put the mixture in a French-press coffee maker and pump the plunger up and down to create bigger foam. That worked! Now we were ready to dehydrate our foam.
Although Eleven Madison Park suggested drying the foam in a low-temperature oven, we opted to use a Nesco dehydrator we'd bought specifically for the purpose. We scooped the milk foam onto a dehydrator tray and turned the machine on at 150 degrees Fahrenheit for three hours.
The results weren’t bad. The scoops flattened a bit, yielding chiplike rounds of dehydrated foam that melted on the tongue but didn't have the richness, density, or thickness we were looking for. Still, in terms of flavor and texture, we weren’t far off. Besides, our foray into modernist cuisine was fun.
For our next experiment, we bought a whipped cream dispenser from Williams-Sonoma and filled it with chilled versions of the milk-glucose mixture as well as melted strawberry ice cream. Both were nice and fluffy when they went into the dehydrator, but the heat melted them almost immediately—we were left with sweet, milky puddles. We weren't sure why. Was it the fat content? Was it a lack of stabilizers? We decided to dip our toe into the world of stabilizers.
Our food-scientist source was Scott Heimendinger, business development manager for Modernist Cuisine. he advised against using gelatin—it melts at just below body temperature, so it wouldn't hold up in the dehydrator. Instead, we tried agar-agar, but it made the foam more like a pudding: One CHOW taster compared it to the filling of Portuguese egg tarts. Frankly, it was like nothing we'd tried before, and nothing like astronaut ice cream.
Finally, we went back to the original milk foam recipe, but this time added two beaten egg whites. Not surprisingly, the results were meringuelike, and the egg helped the foam maintain a lot more volume in the dehydrator. The flavors were too subtle (we'll have to increase the sugar and vanilla next time), but the structure was right: The eagle had landed.
Check back soon for the final results of our experiments in video form.
Photographs by Christopher Rochelle / CHOW.com