This post gets a bit technical and geeky, but I think understanding the theory of cooking is pretty important to cooking well (and consistently). And I can’t stop talking about to people in person anyway, so what the heck.
I’ve experimented with a lot of different cooking techniques over time (clay bakers, pressure cookers, etc.), but nothing has really excited me as much as sous vide. What I really love about sous vide is that it lets you very cleanly separate the two essential goals of cooking:
- Sterilization of food
- Tenderizing/texturizing food
Now, what is it? Sous vide is a cooking technique that aims to evenly cook food through bringing it to a very precisely controlled, even temperature. How it is literally implemented is through placing food in vacuum sealed plastic bags, which are then placed in temperature-controlled water. Vacuum sealing (or, as I prefer, ziplock bagging and pressing out the air) is necessary in order to expose the food to the water more directly. Air is a pretty good insulator, so if it was in between the water and the food, it would prevent the food from getting to the temperature you want it to get to. The water is there because it has a very high specific heat, so it takes a lot of energy to change its temperature. This means it can keep a stable temperature and hold large amount of energy for transfer.
So, what’s so great about this? Well, normally, most cooking techniques just blast heat at food in the attempt to sterilize it and give it an appealing texture. Unfortunately, these two goals are often at crossed purposes. To be safe, we normally heat food to a temperature that instantly kills the bacteria we’re worried about — this ensures that it’s safe, but often at the cost of taste and texture. Anyone who’s eaten a very dry steak can tell you that absolutely-safely-cooked steak is not necessarily tasty steak.
Normally, it’s a bit of an iffy proposition when skewing beneath the instant-kill temperature. Bacteria actually die off at lower temperatures than the recommended temperatures we’re familiar with (160 – 165 degrees F for pork, and chicken, 145 degrees F for steak), but they do so gradually. If you cook at lower temperatures, safety requires good timing, which becomes potentially dangerous enough in the wrong hands that the FDA just always cites instant-kill temperatures.
With sous vide, you take the art (and potential food poisoning) out of the picture and add scientific precision. Sous vide machines are usually accurate enough that you know precisely what temperature the food has been at, and then it becomes a simple matter of looking up the amount of time to get to safety on a food pasteurization table. From there, you can have completely safe food (without blasted and barren texture), which, if you want more flavor/texture, you can apply judiciously without the necessity of hitting instant-kill temperature. For example, browning adds flavor through the mallaird reaction (which doesn’t happen in sous vide). You can either use a food torch or just toss the steak/chicken/whatever onto a hot pan for a few seconds, keeping the internal texture while getting the browning. You can do sous vide with anything (even just a pot of water, a stove, thermometer, and a lot of patience), but in general machine controlled is better. I recently got a deep fryer at an estate sale that I’m not confident in deep-frying in, but can heat water and sous vide with. Unfortunately, the low end of its temperature is still rather high (for sous vide) so I’ll probably be experimenting with putting together my own setup soon.