Cooking with Metrology - Sous Vide
If there were ever to be a cooking method that has everything to do with metrology, it is definitely sous vide.
For those of you that aren’t familiar with the method, it is pretty simple. You vacuum seal some uncooked food in a plastic bag and then place it in a water bath, typically for an extended period of time and what would seem like a relatively low cooking temperature.
The idea here is to get the food to a rather precise temperature and no more.
So for instance, if you like your steak precisely medium, you can use a sous-vide bath to cook them to 135 Deg F and ensure that the doneness does not exceed medium. Then they can be finished quickly on the grill to produce those Milliard reaction grill marks that make a great steak wonderful.
The real beauty of this method is that you end up with a steak that is medium almost all the way through. When you grill a steak traditionally, you only have a small portion of the steak that is actually medium, most of it is well beyond that, so this has become a popular method of cooking.
So about sous-vide, it means under vacuum, in French. Low-temperature cooking was first described by Benjamin Thompson, Count Rumford in 1799. He used air as the heat transfer medium in his experiments while attempting to see if he could roast meat in a machine which he had created to dry potatoes. In Thompson’s own words, the meat was: “Not merely eatable, but perfectly done, and most singularly well-tasted.”
This method was largely lost over time until the 1960’s when cryo-vac bags became commonplace, and the idea was revisited. Moreover, today the technology has become pretty cheap, so it has become a lot more common.
I have to say I was not a fan of the thought of it initially. I saw folks in the late 90’s early 2000’s doing some things that I thought sounded pretty gross. However, when you work with sous-vide it has a lot to pasteurisation, which is an entirely different animal than cooking.
It turns out some brilliant food scientists have done the work to know that if you hold certain foods at specific temperatures for specific lengths of time we can ensure that we have a germ free product.
This can create safe to eat nearly raw meat. I love sushi, but the idea of chicken sushi is not a place I’m going to go…ever. However, I can understand why some people would be interested.
Sous-vide is the pinnacle of food science. There is research done. So we merely have the properties of time and temperature to deal with. The idea here is that we want to kill 99.99999% of the bacteria in the meat. This can be done over a more extended period at lower temperatures.
So here are some numbers for chicken, mind you these are not sous-vide cooking times, just the amount of time the entire piece of animal needs to reach a certain temperature.
Now I’m am going to tell you then you need to make sure you calibrate the temperature of your sous vides set up, I'm a calibration guy, so that's what I do. I purchased a very inexpensive unit on Amazon and was amazed by the accuracy. It claimed 0.1 degrees, which I knew was bogus, but it was less than a half degree variation from nominal, which was pretty impressive.
However, your mileage may vary here, so make sure you check things with a calibrated thermometer. Also super crucial with sous-vide, make sure your device can handle the size and insulation of vessel you are using to sous-vide. You can do this by taking some measurements throughout the water bath you are using, make sure you have reasonable uniformity, you can also check it after the food is nearly done based on time, by then the temperature should be very uniform.
This is super important with sous-vide because the temperature is our most critical element to ensure food is safe.