Kitchen Mysteries is a weekly exploration of oddities surrounding cooking and food. They could be recipes that fail when they shouldn’t, conflicting advice from different sources, or just plain weirdness. If it happens in a kitchen, and you’re not sure why, send a tweet to The Food Geek to find out what’s happening.
Friend of The Food Geek Snitty asks:
Sous vide is a cooking technique that I first discovered through Iron Chef. That’s the original series, not Iron Chef America. The competitor was some kind of sous vide master, having studied at the feet of the monks in France to perfect his vide-fu. Or something. It’s been a few years since I’ve seen the episode. There was probably cooking involved.
Here’s the idea: the difficult thing with food is getting it to its proper temperature. If the temperature is too low, then the food tends to be kinda gross. If the temperature is too high, then it’s burnt and/or dried out. Some foods have a decent range of temperatures at which they can be heated and still worth eating, but many are particularly finicky.
Poaching is one way to solve this problem: you take food that you’re cooking and put it into a liquid. Bring that liquid to the temperature that the food is ultimately supposed to reach and, after some relatively flexible amount of time, you have a cooked item. In many cases, the cooking liquid also imparted some flavor to the food.
The downside of this technique in some instances is that the cooking liquid interacts with the food in ways other than imparting flavor. It might wash away nutrients. It might affect the texture by dissolving connective tissue. You can be sure that a dry-rub isn’t going to last with it. So it’s not useful for all applications.
Sous vide says, “Hey, we live in the modern world. Why have the liquid touch the food. Instead, cover it in plastic, and voila, you have poaching without messiness. Plastic is the future, after all. Space age materials. Woo!”
Typically, foods being cooked sous vide are put in plastic, placed into a vacuum chamber sealer, have all the air sucked out, and are placed in a water bath. This water bath is set to a precise temperature by a device called an immersion circulator. After a certain amount of time, the food is removed from the bath, removed from the plastic, plated, and served.
So, to reiterate Snitty’s question: is the equipment necessary? Do we need both an immersion circulator and a vacuum chamber sealer? The quick answer is “No, you don’t.” The other quick answer is, “Yes, you do.” And, because that’s completely unhelpful, we’ll go to the long answer.
The phrase, “sous vide,” means, “under vacuum,” in the original French. Therefore, if you aren’t using a vacuum sealer, it’s not strictly sous vide. The French would sure look down upon you for even having considered the question.
Still, you’re an improvisational home cook, and the real, we want to find out how far we can go without the proper equipment. A goodly distance, as it turns out.
The purpose of the vacuum sealer is to ensure that all of the heat transferring into the item being cooked is from conduction. Conduction, while not terribly efficient, is a very predictable cooking method. Convection is all swirly fluids and random gusts of air and, while it carries heat quickly and well, it’s a little chaotic. By ensuring that there is a solid layer of a not-terribly conductive bit of plastic touching your food without any air pockets, you get a buffer against the vagaries of the convection.
In order to simulate this advanced setup, I recommend starting with a zip-top bag and a straw. Or, if you’re feeling extravagant, one of the new zip-top bags with the pump that you can attach to it. What you can do with this is throw in a piece of meat or fish covered with some herbs, spices, or a paste, seal it up, and remove a great deal of air. What it won’t do is let you deal well with liquids in the bag. It can be done, but it’s tricky.
Yes, yes, I said the point of this technique was to avoid liquids. That is one of the advantages, to be sure, but people do crazy things with sous vide. You can’t expect someone to pick up a new toy and not go and try everything out with it. Still, you can have much more concentrated liquids in the sous vide cooking, so that it’s more like braising than poaching.
One of the downsides of the zip-top bags, and even the home vacuum sealers, is that the plastic isn’t all that thick. This means that higher temperatures may warp the plastic, which might not be a good idea. Limiting your temperature means that you probably won’t be able to cook vegetables. Meats and fish, sure; vegetables, no.
Now: thermal immersion circulator. This is a scientific-grade device thats purpose in life is to ensure that the water that your food is sitting in remains at an exact temperature within, say, a tenth of a degree. They do this by pumping water past a heating element. If the water’s too cold, you turn the element on. If it’s too warm, you leave it off. Typically, these go for about $1000 if you’re getting the basic model. That is quite a bit of money.
If you were The Food Geek, you might, say, build your own immersion circulator. I am working on it, but it’s in the early stages so far. If it all works out, I’ll let you know how to make your own. For those who are not interested, you can get by without. The only trick is to regulate temperature.
With most stovetop cooking, you can get by with boiling or simmering your liquids. With candy making, as I’ve mentioned before, you have to use a thermometer, but it’s more that, once you get to a particular temperature, you stop the cooking. With sous vide. you have to maintain that temperature for quite a bit of time.
Now, you don’t need to keep everything within a tenth of a degree, but do think about what you’re cooking: if it’s beef, you probably have a 5-degree range that you can stay within without causing any trouble. With fish, closer to 3 degrees, depending on the thickness. Still, meat is not a good conductor. The idea behind sous vide is that you’re not constantly pouring heat with an efficient transfer mechanism such as oil or copper so that it all penetrates quickly. You’re going over a long period of time. Once you have your oven heating your liquid evenly without major temperature spikes, you can probably leave it alone for 10-15 minutes at a time. It’s probably much easier on a gas range than an electric one.
There is a lot more to know if you want to get into sous vide, and I recommend the Practical Guide to Sous Vide Cooking by Douglas Baldwin. I found this one from the always worthwhile khymos.org. And, if you’re curious about what you can really do with the technique given the time, ingredients, equipment, know-how, and skill, I recommend the book Under Pressure by Thomas Keller.
Let me know if you give it a try. I’m always interested to see how these experiments go. If you (this goes for all of you) are interested in more information on sous vide or any other food topic, be sure to send me an email or tweet and I’ll see if I can’t give you a good answer.