Kitchen Chemistry: Liquid Nitrogen Ice Cream


With summer coming to an end are you looking for a backyard barbecue menu that will end the season with bang, amazing your friends and neighbors? Well, with some chemistry and engineering knowledge - and gobs of time - your culinary show will wrap up the summer with a big hit.

To start on a tangent, I am intrigued by the comparisons between bakers and chefs. Bakers use chemistry in very visible ways (leavening agents in breads), using exact measurements (if you don't measure your baking soda correctly those cookies will not taste the same) and times. It would not be out of place to bake in a lab coat.

Chef, baker, artist, chemist

Meanwhile, chefs are full of flair and sometimes care as much about the color palate as the tasting palate. They are viewed by some as artists that use pinches, dashes, and drizzles. Full disclosure: in our household I (full-fledged engineer) am the chef and my wife (architect) is the baker. Not that we have strict territorial lines, but that is how things generally fall. And not that we fit neatly into those categories either. She likes the simplicity of baking with a few ingredients...as well as the outcome. She bakes like Grandma used to - she rarely pulls out the recipe card, rather working a crust until it feels just right. I on the other hand, am fascinated by how chemistry makes food better. How searing at the right temperature works magic on proteins, how caramelization transforms sugars, what salt activates in the senses. But enough of the talk...back to the food.

Chemistry finds its rightful place in the kitchen

There is a lot of time and equipment required here, so I thought it would be best to start with a short menu. The first item is out of what could be considered the Perry's Handbook of cooking - the beautifully crafted six-volume set of Nathan Myhrvold's Modernist Cuisine. As with most serious reference books, this can set you back quite a bit - around $500. But also like most serious reference books, this will take you from History and Fundamentals through Basic Techniques and analysis of the building blocks of a meal to final plating and serving.


This burger may look good, but it's definitely not Myhrvold's perfect burger.

As if the information weren't enough, it is accompanied by amazing photography - they cut ovens in half to show what is happening inside. The Perfect Burger (which can be seen here) was dissected in a Freakonomics podcast - don't miss Part 2 where they discuss printable food and how it can help disaster relief efforts. The burger is comprised of elements as simple as a fresh baked bun, but most of it is more complex, including (but not limited to) hickory smoke infused lettuce, vacuum compressed heirloom tomato, and crimini mushroom ketchup with honey, horseradish, fish sauce, ginger, and allspice. And can require a lot of equipment - the patty itself needs sous-vide preparation, liquid nitrogen, and a deep fryer or blowtorch.

Don't have the estimated 30 hours (and uncounted amount of money for equipment) to throw one of these together? There are many restaurants that feature this molecular gastronomy. I have visited Moto - Chicago's marquee experimenter, and it was quite the experience. Amazing and creative things are done with food that make you feel somewhere in between Dr. Seuss, Star Trek, and Bill Nye. Go with an open mind (and, fair warning, an open wallet).

Molecular gastronomy shortcuts

Not to be anti-climatic, the rest of the dishes are far simpler to complete but still satisfying. A light summertime snack that is fun for kids of all ages lounging in the backyard, or anywhere else: carbonated fruit. This might be cheating a little since Fizzy Fruit does the work, but everyone will still enjoy it. The company carbonates the water in fruit - grapes, pineapple, watermelon, oranges, and more - to give them a little extra sparkle. Then onto the grand finale - Nitrogen Ice Cream.

The science of conventional ice cream

How to make your own homemade ice cream is wonderful; I think everyone can agree on that. But few are willing to wait for the mixing and freezing. Or do the churning or have a machine to do it for them. The creaminess of ice cream comes from the crystal size - the smaller the crystal, the creamier the final product. The churning during freezing keeps the forming crystals smaller, compared to if the mixture were simply placed in a freezer until frozen solid. The speed of freezing process also affects the crystal size.

Making liquid nitrogen ice cream

In a standard ice cream process, rock salt is added to ice to allow the water to maintain liquid phase at a lower temperature, thus increasing the heat transfer. A more effective cooling method is liquid nitrogen. The extreme coldness of liquid nitrogen freezes the ice cream base quickly, while the rapid boiling of the liquid nitrogen aids in the churning. Not to mention it boils right off, making for easy cleanup. Since the liquid nitrogen is so cold you can also eliminate the skill intensive step of making the standard ice cream base and use a simple eggless recipe such as this one. Or for the full upgrade, try these guys.

I don't have any recommendations for where to obtain liquid nitrogen, but there are some standard safety recommendations. Liquid nitrogen can be harmful if held or touched with unprotected skin (quick and severe frostbite). Use insulated containers for handling, gloves, and safety glasses along with all other standard safety practices.

Have you ever applied your chemistry knowledge to culinary pursuits?

Photos: ice cream, istockphoto.com; burger, gabriel amadeus via Flickr; liquid nitrogen tank, flagbow via Flickr

Comments

johnvasko's picture

Robert, this is a great post. It's amazing to me how much chemistry is involved in cooking regardless of whether people realize it or not. I don't think I'll be trying to make liquid nitrogen ice cream anytime soon but the fizzy fruit sounds fascinating..

Robert S's picture

Thanks, the fruit is fun.