I spent a couple of weeks last month performing experiments in my kitchen using a cooking technique known as “sous vide” (means “under vacuum” in French).
In sous vide cooking you generally vacuum seal (or use inert gases to supplant oxygen) foods and then cook them for a long time at low and consistent temperatures (typically in the range of 50-72 degrees Celsius / 122-158 degrees Fahrenheit).
Sous vide cooking is quite equipment intensive, as it requires, at a minimum, a decent vacuum sealing device, and a way to cook at specific temperatures with a high degree of accuracy (.1 degrees Celsius accuracy is desirable). While there probably are some passable low-priced solutions, if you’re serious about doing a wide range of sous vide cooking at home, I would strongly suggest budgeting about $5,000 for the two key components you will need – the vacuum sealer being one, and the other discussed below.
The common way to achieve the accurate temperature needed is via a device known as an thermal immersion circulator, placed in a water bath. The immersion circulator sucks in water, and then jets it out, heating the water in the process. A highly accurate thermometer built into the immersion circulator is used by the device to ensure the water is not over-heated, but instead kept at the exact temperature programmed into the device. Thermal immersion circulators originated as a piece of laboratory equipment for chemical and biological work, and the original idea to use such a device stems from the “bain marie“.
For my kitchen, I had invested in a C-100 vacuum sealer from Multivac, based on a recommendation and contact information provided by Wiley Dufresne, chef at wd-50, New York’s landmark molecular gastronomy restaurant (although they call it “New American” cuisine on the web site).
Interesting side note: Unbeknownst to us, Wiley sat behind us at a presentation on cooking with liquid nitrogen in New York City about 16 months ago, and by coincidence recognized us from that class when we dined at his restaurant the following night. Wiley invited us into the kitchen for a tour after dinner to show us his modern kitchen and equipment, including containers with all of his “ingredients”, and described some of the cooking techniques he uses. All I can say, other than “Thank you Wiley!”, is that you should not miss an opportunity to try wd-50 the next time you’re in New York City!
A web site on sous vide pointed us to some sources for immersion circulators. We ended up going to the Cole-Parmer web site, which offered a number of options for immersion circulators. I opted for the Techne TE-10D (pictured further above), which features a digital display (and settings), and also a screw clamp which can be used to mount the immersion circulator onto a large pot which holds your cooking medium (water), and which is turn is used to cook your vacuum sealed bags of edible goodness.
Sous vide, as a form of culinary artistry, is still evolving. Its origin in food preparation came from a desire to seal food away from the things that cause it to go bad, such as oxygen and the bacteria that need oxygen to multiply (although there are anaerobic bacteria that could cause problems). At some point someone tried cooking vacuum sealed food while still in the plastic bag and found it could make a dramatic improvement in juiciness, as well as retention of flavor and nutrients. Part of that is because the food is not exposed to air while it cooks. Air will oxidize meats and change their color (brown, typically) and flavor, and similarly, vegetables will lose flavor when cooked in water, steam, or in a pan with fats of any sort.
However, in a vacuum, that’s not an issue – the meat cooks in whatever marinade you have it stored in, as well as its own juices, which would otherwise evaporate. Further, by being able to cook meat and other foods at exact temperatures, you can select the proper level of done-ness throughout instead of the temperature variations that oven-based cooking produces – namely higher heat and thus dryness on the outside going into the meat, and cooler temperatures and less done-ness inside at the center.
What I find fascinating about this process is that it combines science with food, as you need to learn and know at what temperature various foods change states. For example, the proteins in egg yolks firm up at just around 65 degrees Celsius (149 degrees Fahrenheit), but the several different parts of egg whites coagulate at different temperatures, both higher and lower than the egg yolk. And beef is a perfect medium rare (as far as I’m concerned anyhow) at 54.5 degrees Celsius (130.1 degrees Fahrenheit).
One of the cautions with sous vide cooking is that the same low temperatures at which you cook meats are the same temperatures at which bacteria thrive, so if your food source or preparation are not properly hygienic, you could be breeding organisms which lead to food poisoning. There are a number of ways to minimize or remove the risk, including thoroughly cleaning and washing foods before sealing them, searing the outside of meats at high heat in a broiler or pan to quickly kill off any unwanted guests, or using alcohol in your sauces or marinades. More details on this subject can be found here.
A book I am reading about Sous Vide right now which promises to be excellent (and some say it’s the “Bible of Sous Vide”) is the difficult to obtain and unfortunately expensive ($160 and up) “Sous-Vide Cuisine” by Joan Roca and Salvador Brugués. I bought mine here. Thomas Keller of French Laundry and Per Se fame also has a book out on sous vide cooking, “Under Pressure: Cooking Sous Vide” which has some fascinating recipes but does not really address basic sous vide experimentation. And finally, no discussion of food science would be complete without a recommendation of Harold McGee’s most excellent “On Food and Cooking, 2nd Edition“.
In order to not make my posts novella-length, I’ll address actual sous vide cooking experiences in another entry to be posted early next week. For now, let me leave you with a photo of a sous vide cooked egg – creamy, custardy whites with a thick gooey full-flavored yolk. Trust me. It was delicious.