Archive for November, 2010

Precise Temperature Control Cooking; Sous Vide Water Oven

Thursday, November 4th, 2010

Cooking food with heat is a far more subtle process than simply applying heat. Beyond that doubling the temperature obviously doesn’t cook something twice as fast, there is a vast array of stunningly complex chemical reactions that occur as food is heated.

Even the seemingly simple act of hard boiling an egg will cause the yolk and white to pass through nearly a dozen different phases as different temperature thresholds are crossed and different proteins and nucleic within the white and yolk are denatured. For an egg, the difference between clear, runny, jelly-like, and hard boiled is only a matter of degrees!

And some reaction can take quite a while, too. Making pulled pork, something for which I have a bit of experience, involves heating the meat to a temperature such that the collagen and fat effectively changes from a tough, chewy, substance into liquid or a jello like cloud of delicious. Done right, this can take hours or, even, days.

With a stove, grill or — even — an oven, it is extremely difficult to both maintain a constant temperature and not dry the food out.

Enter sous vide.

Sous vide means, literally, “under vacuum”. That is, in sous vide cooking, the food is vacuum packed, often with spices or marinades. The actual process of cooking, though, is generally done in a water oven; a device that can maintain a bucket of water at a very precise temperature.

Precise as in the ability to cook an egg to exactly 144 degrees throughout, just hot enough that the white is semi-solid but still runny while the yolk is nearly, but not totally, liquid. I.e. the perfect poached egg. Or 72 hour pulled pork at 141 degrees that comes out fork tender, medium-rarish, but with the flavor of ham. Or the perfect rare, fork tender, short rib by cooking at 138 for 48 hours.

“But, wait!, pork at 141?!?! Beef @ 138? The FDA says we need to reach ~160 for them to be safe!! You are gonna kill someone!”

Those temperatures are actually the instant kill temperatures for food borne pathogens. If you get the inside of a steak to 166, all bad critters will be dead. However, said same critters cannot survive at ~135 or above and, thus, if you keep the meat at said temperature for long enough, the bad critters will generally be just as dead.

This isn’t the end of the story and I encourage you to both read Douglas Baldwin’s Sous Vide for the Home Cook and, covering much more than just sous vide and the single most accessible and entertaining science oriented cookbook around Jeff Potter’s Cooking for Geeks: Real Science, Great Hacks, and Good Food
(seriously — get this book — even if you have a moratorium on cookbooks, get this book!!).

I had the pleasure of hearing Jeff speak and having lunch with him. It was that conversation that convinced me to dive into Sous Vide cooking; it scratches all of the über-control penchant of my geekiness while promising to yield new potential heights to appease my chefiness.

At left is the SousVide Supreme, an appliance that quite conveniently maintains a bath of water at whatever temperature you want from less than 100 degrees up to just below boiling point.

There are also a number of homebrew solutions and lab quality circulators (no surprise, heating some live soup of pathogenic critters to ideal reproduction temperatures is a long solved problem in the lab). And you can go the PID controller route and whip up a hot water oven for ~$50 (link to an excellent write-up on doing exactly that).

I personally chose the SVS both because I didn’t have a crock pot and the good quality lab circulators are typically considerably more expensive. As well, the margin for error with Sous Vide can be pretty damned narrow when cooking at the border of pathogenic reproduction temperatures; best to have a dead accurate unit than one that is off by 5 degrees.

NOTE: Since writing this article, I sold my SVS to a friend and upgraded to the Polyscience Sous Vide Professional. While more expensive, it is both slightly more accurate and, the motivating factor, vastly more versatile. As an added benefit, there is no big, single purpose, metal tub. Storing the Polyscience circulator takes vastly less room and the device can maintain temperature on a truly huge tub of water (up to 30 liters). I have various sized Cambro food trays and, thus, I can choose a smaller container when doing a handful of eggs, a deep container when doing very veggies that like to stand up, or a really large 25L relatively shallow container when cooking 5 slabs of my now infamous 65 hour tropical BBQ pork ribs!

For vacuum sealing, I’m using a FoodSaver v3840 upright sealer. In hindsight, I would much rather have a clam shell vacuum sealer as they waste less bags and, though seemingly less convenient, are easier to align the bag for sealing purposes.

In the 2 weeks I’ve had the SVS, I’ve been able to produce some truly amazing foods (and one really bland bit of food). I’ve learned a lot and also come to realize that this is really an area of cooking for which there is no deep history or reference tome. A lot of times you are on your own. And as long as you follow the safety rules put forth in both Douglas’s and Jeff’s books, you’ll always be safe even if your meal turns out inedible (as Jeff likes to say, even the worst meal can be improved by a quick call to the local pizza delivery service).

Read the rest of this entry »