Wednesday, October 19, 2011

My first foray into the modern cooking movement

Holding steady at 140° F
I started cooking a lot more when I met my wife. And by that I mean I helped her when she cooked. I was still a relative novice but wanted to learn. The really tricky part was figuring out where to start. We realized early on that our styles where quite different which led to a few clashes in the kitchen.  Mostly because I asked way too many questions. Deb cooks more on taste and feel and I want to know what's going on under the hood. I discovered a book called Cooking for Geeks which, as you can probably tell, spoke to me immediately. It dives into the chemistry and physics of cooking right away and delivers it in an easily understood manner. I was particularly enthralled with the chapter on Sous Vide cooking. Not only was the science noteworthy but the hardware involved was also of particular interest to me. Unfortunately the cheapest commercially available unit costs in the range of $400. Okay, I was gonna build one before I even knew the price tag.

Sous Vide, pronounced "Sue Veed", is a way of cooking food by submerging it in a very accurate temperature controlled water bath. The food is vacuum sealed in a plastic bag to keep the water out and keep the moisture and aromas in. This method eliminates any chance of overcooking the meal and ensures that it is heated evenly throughout.  You get a perfectly done steak or piece of fish every time. More about that later though.

With pretty much all of my projects, I like to start off by scouring the internet to get a good idea of what's already out there. I found this little gem on Make and figured it was a great place to begin. The design revolves around a PID controller which continually reads in the water bath temperature with a k type thermocouple and cycles three heating elements either on or off based on the current temperature, rate of temperature change and distance from desired temperature.  Normally it would be a lot cooler if I made my own controller but for $30, it was hard to beat the off the shelf unit they spec'd.

Sheet Metal Work
I was't a fan of the enclosure they used so I leveraged my meager metal working skills and made my own.  Making cut outs in 1/8" aluminum is not fun. After cutting a series of smaller holes on the drill press, I filed down the inner edges to make them flat and smooth. To make the box, I bent all the side walls toward each other and used epoxy where they met on the inside to secure them in place. More grinding was necessary to round off the joints.  This was the most time consuming portion of the project. Took a few iterations of sanding and priming to get the edges just right.  I was quite please with how they turned out.  Like the paint job?  Gotta thank my pal Tommy S. for the inspiration. How better to paint a slow cooker than with racing stripes. Check out the nod to the French racing blue Renault Clio 182.

I think it's time to talk performance and results. The controller and associated thermocouple kept the water bath temperature within two tenths of a degree of the set temp.  That's more than accurate enough for the purpose of this machine. And when heating up room temp water, it can add enough energy to increase the temp of about two gallons of water approximately 2°F per minute. That's not great but considering the water coming out of the tap can reach about 130°F, you really don't have to wait too long.

Perfect medium rare steak
I decided to start the real testing with something easy, a couple of 5oz filet mignon steaks. Flanked the meal with some roasted yukon golds and sauteed broccoli. I set the immersion cooker at 140°F, vacuum sealed up the meat (covered in a little garlic, thyme, olive oil, salt and pepper) and let it cook  for an hour and fifteen minutes. As a result of cooking at a relatively low temperature, the browning reactions normally associated with a steak will not take place. This is easily overcome with some quick searing action on a smoking hot cast iron skillet. Around 45 seconds a side should do it. As you can see in the picture above, the steak is cooked evenly throughout. I also verified with a thermometer that the meat was a perfect 140°F. A little moisture was left over in the bag but not enough to really matter. The resultant steak was extremely tender and juicy.  

The obvious drawback to this style of cooking is the long cook times necessary to neutralize any bacteria present in the food. Bacteria will die within minutes at 160°F but it takes considerable longer at lower temperatures. There are many guides available to aide you with these calculations. I don't mind the long lead.  My thinking is, where's the fire baby? Life is to be simmered and enjoyed.  Sous Vide isn't for every meal but it does add another interesting preparation option in the kitchen and a good one at that. I'm looking forward to further experimentation and more delicious food.


Francis said...

Truly inspired! thanks for sharing Evan. I hope to sample some vegan sous vide. do you vacuum seal in plastic? If so, what are the leaching issues?

I am already tasting a perfectly cooked portabella...

Anonymous said...

How about searing the meat first before cooking? That would sterilize the surface of the meat and seal in the juices. The bacteria should only be on the surface. Excellent job, I'm tempted to have a go as I've never been able to cook beef very well!

michael said...


google it.

Evan Flint said...

@michael - You are right, searing doesn't really seal in the juices but it does cause the maillard reactions that bring out a ton of flavor. @Anonymous - I seared it after I took it out of the sous vide cooker. All of the bacteria was dead by then.